THE SPECTROGRAPH Volume 24, Number 1 Fall 2007

George R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology

Townes gives fi rst New space for Spec Lab Dasari Lecture By Michael S. Feld “Charles Townes is the perfect per- On October 5 MIT celebrated the comple- son to inaugurate the Dasari Lectures,” tion of its two-year, more than $50 million said Harrison Spectroscopy Labora- dollar construction project in Buildings 4, tory Director Michael Feld. That his 6 and 8. The project, called PDSI because assertion was no hyperbole became ap- it was undertaken for the Physics Depart- parent as Professor Townes gave his ment, the Department of Materials Sci- lecture, “The fun of a physics career.” ence and Engineering, the Spectroscopy His invention of the maser and, with Laboratory, and for Infrastructure, provides modern research facilities and much needed new space. The heart of the cel- ebration was the dedication of the Green Center for Physics, which brings many physics faculty together in Bldg 6 and the newly built Bldg 6C. For the Harrison Spectroscopy Labora- Sol LeWitt’s work of art, “Bars of Colors within tory PDSI provides a new physical plant Squares” surrounds the new space (MIT) 2007 Pho- for modern research and applications tograph by George Bouret in spectroscopy. This modernized and trum of proteins. Later during that period expanded space allows the Spec Lab to Ali Javan and Charles Townes brought continue to offer researchers the most ad- lasers into the Spec Lab and opened the vanced equipment of the day and to con- era of modern spectroscopy. solidate and extend its remarkable tradi- As MIT’s fi rst interdepartmental Dr. Dasari presents the Bhagavad Gita to Prof. tions of interdisciplinary research. laboratory, the Spec Lab has always fos- Townes at the fi rst Dasari Lecture on Oct. 9 Since its founding in 1931 by Karl T. tered interdisciplinary research. Since I Arthur Schawlow, extension of the idea to Compton and George R Harrison, the became its director in 1976, we have striv- the laser, created essential tools of mod- Spectroscopy Laboratory has been a ma- en to expand and exploit the opportunities ern laser spectroscopy. When Townes jor center for research in spectroscopy. of such research. In 1979 the National came to MIT as Provost in 1961, Ali Ja- From the start it offered advanced facili- Science Foundation established a Region- Space, continues on page 2 van came with him. Their research on the ties of outstanding capability. With its fundamentals of laser physics and spec- specially built vibration-isolated building Also in this issue troscopy led to advances in understanding and its 40-foot walk-in spectrograph, the and technique that profoundly shaped the Spectroscopy Laboratory was tailor built ~Research Report subsequent development of the Spec Lab. and equipped for high resolution spectros- Hydrogen bond exchange in water copy. The world’s most precise diffraction Townes told a large and attentive audi- Research Report gratings were ruled here, and the famous ~ ence about the high points of his remark- Tomographic Phase Microscopy able career, a career in which he continues MIT wavelength tables were compiled to be productive at age 92. He stressed here. (This depression-era project kept ~Fall Seminar that serendipity taught him an unusual many unemployed physicists at work!) Modern Optics and Spectroscopy The Spec Lab has led in advances in mixture of theory, practical engineering ~Lester Wolfe Workshop theory and applications of the interactions knowledge, and experimental technique Modern Microscopy crucial to his successes. He also drew an of light with matter, the essence of spec- important moral from his experiences. troscopy. After he succeeded George Har- ~Spectral Lines When leading physicists of the day, in- rison in 1946 to become Director of the More than a burner cluding the head of his department at Spec Lab, Richard Lord pioneered devel- ~Editorial opment of Raman and infrared spectros- Columbia University, told him he was Original work in The Spectrograph Townes, continues on page 3 copy and obtained the fi rst Raman spec- Space, continued from page 1 There are twelve refurbished and new build on the achievements of the past to al Instrumentation Facility in association laboratories located on the ground fl oors realize wonderful opportunities for new with the Spec Lab and supported it for 26 of Bldg 6 and the new Green Building advances in basic research and applica- years. The center brought in resources and (6C). Each laboratory has been designed tions of spectroscopy for societal benefi t. attracted faculty members and has led to to meet the needs of an individual re- ongoing collaborative and multi-disciplin- search group and to enhance the multi- ary research among faculty from Chemis- disciplinary interactions among Spec Lab Spec Lab creates 3D try, Physics, Electrical Engineering, and students and staff members from different Chemical Engineering. Since 1985, the groups and departments. These labs oc- images of living cell cupy more than 8,000 square feet and pro- National Institutes of Health has support- Anne Trafton, MIT News Offi ce ed the Laser Biomedical Research Center vide facilities for wet chemistry and cell- biology preparations. The labs provide the (LBRC) in the Spec Lab. This national This article is reprinted from the August 12, 2007 resource for conducting cutting edge re- resources to: edition of Tech Talk with permission from the MIT search with lasers, light, and spectroscopy •Study quantum dots as probes for im- News Offi ce. has been notably successful in fostering aging biological micro-environments interdisciplinary innovative basic and ap- •Synthesize and characterize carbon A new imaging technique developed plied research in biology and medicine. nanotubes using Raman spectroscopy and in MIT’s Harrison Spectroscopy Labo- The diversity of researchers in the Spec other techniques ratory has allowed scientists to create Lab is an important aspect of its interdis- •Use ultra-fast two-dimensional infra- the fi rst 3D images of a living cell, us- ciplinary and collaborative work. Students red spectroscopy to probe molecular dy- ing a method similar to the x-ray CT and staff from many countries, back- namics in condensed phase systems scans doctors use to see inside the body. grounds, and races stimulate and enhance •Use photo-acoustic spectroscopy to The technique, described in a paper pub- the Spec Lab’s environment. By nurtur- study thin fi lms and materials lished in the Aug. 12 online edition of Na- ing diversity in a variety of ways, the Spec •Train high school students and teach- ture Methods, could be used to produce the Lab helps MIT to increase and support ers in thin-fi lm dynamics and other areas most detailed images yet of what goes on more diversity in the academic and sci- (Outreach Laboratory) inside a living cell without the help of fl u- entifi c and engineering professions. The •Study combustion dynamics orescent markers or other externally added Spec Lab will continue and expand its ef- •Study stochastic gene expression and contrast agents, said Michael Feld, Direc- forts in this area. related processes (biophysics laboratory tor of the George R. Harrison Spectrosco- and cell preparation facility) py Laboratory and a professor of physics. THE SPECTROGRAPH •Develop techniques and instruments “Accomplishing this has been my Published by the George R. Harrison Spec- for spectral diagnosis and imaging of dis- dream, and a goal of our laboratory, for troscopy Laboratory at the Massachusetts ease several years,” said Feld, senior au- Institute of Technology, Cambridge, MA •Develop and apply instruments for thor of the paper. “For the fi rst time 02139-4307. Comments, suggestions, and phase and tomographic microscopy of live the functional activities of living cells inquiries can be directed to the editor. cells, small organisms, and tissues. Editors: Charles H. Holbrow and Geoff All the staff and faculty of the Spec Lab O’Donoghue are heartened by the forward looking deci- GEORGE R. HARRISON sion of the Institute to upgrade and mod- SPECTROSCOPY LABORATORY Director: Michael S. Feld ernize the Spectroscopy Laboratory. We Assoc. Director for Scientifi c Coordination: are grateful to President Hockfi eld, Pro- Robert W. Field vost Reif, and Associate Provost Claude Associate Director: Canizares for their support. Dean Robert Ramachandra R. Dasari Silbey’s leadership and support for the Spec Lab throughout the PDSI project is The Spectroscopy Laboratory houses two laser gratefully acknowledged. We especially research resource facilities. The MIT Laser Re- thank the numerous benefactors who con- search Facility provides shared facilities for core researchers to carry out basic laser research in the tributed to the PDSI project in general, physical sciences. The MIT Laser Biomedical and to the Spectroscopy Laboratory con- Research Center, a National Institutes of Health struction in particular. Our thanks go also Biomedical Research Technology Center, is a to the many staff members of the Depart- resource center for laser biomedical studies. The ment of Facilities, led by John Hawes, LBRC supports core and collaborative research who worked on this project. in technological research and development. In addition, it provides advanced laser instrumenta- Spec Lab professors and staff and stu- tion, along with technical and scientifi c support, dents - especially Luis Galindo and Geoff free of charge to university, industrial, and medi- O’Donoghue, Spec Lab engineers, and cal researchers for publishable research projects. Ramachandra Dasari, the lab’s Associate Call or write for further information or to receive Director - worked hard and long to design, Asst. Prof. Dr. Kamran Badizadegan, Postdoc- our mailings. organize and move into the new space. All toral Associate Wonshik Choi, and Prof. Michael (617) 253-4881 Feld display their new apparatus / Photo Donna http://web.mit.edu/spectroscopy these efforts will let us work together and Coveney Page 2 can be studied in their native state.” microscopy and other approaches. Personality Using the new technique, the Spec Lab “One key advantage of the new tech- team has created three-dimensional im- nique is that it can be used to study live Luis Galindo ages of cervical cancer cells, showing cells without any preparation,” said Kam- By Mei-Hui Liu internal cell structures. They’ve also im- ran Badizadegan, principal research sci- aged C. elegans, a small worm, as well as entist in the Spectroscopy Laboratory and several other cell types. assistant professor of pathology at Harvard The researchers based their tech- Medical School, and one of the authors of nique on the same concept used to cre- the paper. With essentially all other 3D ate three-dimensional CT (computed imaging techniques, the samples must be tomography) images of the human body, fi xed with chemicals, frozen, stained with which allow doctors to diagnose and dyes, metallized or otherwise processed treat medical conditions. CT images are to provide detailed structural information. generated by combining a series of two- “When you fi x the cells, you can’t look dimensional x-ray images taken as the at their movements, and when you add ex- x-ray source rotates around the object. ternal contrast agents you can never be sure you haven’t somehow interfered with nor- “...For the fi rst time mal cellular function,” said Badizadegan. the functional activi- The current resolution of the new technique is about 500 nanometers, or bil- Luis Galindo holds a probe in his optical fi ber ties of living cells can lionths of a meter, but the team is work- research facility be studied in their ing on improving the resolution. “We are Luis Galindo attended National Universi- native state...” confi dent that we can attain 150 nano- ty of Colombia in Colombia as an under- meters, and perhaps higher resolution is graduate, earning a B. S. in Engineering “You can reconstruct a 3D representation possible,” Feld said. “We expect this new in 1979. He came to the U. S. in 1982 of an object from multiple images taken technique to serve as a complement to and has lived in Massachusetts since then. from multiple directions,” said Wonshik electron microscopy, which has a resolu- Over the years he has earned a techni- Choi, lead author of the paper and a Spec- tion of approximately 10 nanometers.” cal degree in Computers and Electronics troscopy Laboratory postdoctoral associate. Other authors on the paper are in the U. S. and in Industrial Robotics in Cells don’t absorb much visible light, Christopher Fang-Yen, a former post- Germany. He has worked at the Spectros- so the researchers instead created their doctoral associate; graduate students copy Laboratory since 1997. Before that images by taking advantage of a prop- Seungeun Oh and Niyom Lue; and Ra- he traveled around the world working as erty known as refractive index. Ev- machandra Dasari, principal research a service engineer for Spectro Analyti- ery material has a well-defi ned refrac- scientist at the Spectroscopy Laboratory. cal Instruments, a German company that tive index, which is a measure of how The research was conducted at MIT’s manufactures optical emission and x-ray much the speed of light is reduced as it Laser Biomedical Research Center and spectrometers. After two years in Mexico passes through the material. The higher funded by the National Institutes of Health as a service manager, he came back to the index, the slower the light travels. and Hamamatsu Corporation. the U. S. as a technical manager for Latin The researchers made their measure- America and the Caribbean. ments using a technique known as inter- At the Spectroscopy Laboratory, Lu- ferometry, in which a light wave passing is’s primary function is to build Raman, Townes, continued from page 1 through a cell is compared with a refer- MMS and FastEEM probes. He has been ence wave that doesn’t pass through wasting his time trying to make a maser, involved in the design and development it. A 2D image containing information he persisted. When he set out to look for of the Raman probe for many years. He about refractive index is thus obtained. evidence of molecules in space, again im- also fabricates micro optics for the Ra- To create a 3D image, the research- portant physicists told him the search was man and MMS probes. Luis performs ers combined 100 two-dimensional im- futile; again he persisted. The moral he administrative duties and helps with ages taken from different angles. The drew: Use your own judgment to choose mechanical, electrical, and electronic resulting images are essentially 3D maps your research goals; then pursue them with development of clinical instruments. of the refractive index of the cell’s or- courage, determination, and persistence. Luis enjoys working at the Spec Lab. ganelles. The entire process took about Both Michael Feld, who was Javan’s stu- He declared, “It has been a great experi- 10 seconds, but the researchers re- dent, and Ramachandra Dasari, who spent ence, the experience of a lifetime, working cently reduced this time to 0.1 seconds. two years as a visiting fellow with Javan’s here. There is not a day goes by without The team’s image of a cervical cancer and Towne’s research group, recalled the learning something. What I like most are cell reveals the cell nucleus, the nucleo- years Townes was at MIT as particularly the challenges that come my way and that lus and a number of smaller organelles exciting. The memories they shared with I am able to meet. I hope it stays that way in the cytoplasm. The researchers are the speaker and the audience gave special always.” Luis also enjoys spending time currently in the process of better char- warmth to the occasion. “It was for me a at home with his wife Marilyn, a native of acterizing these organelles by combin- great joy to have Charlie Townes be the Puerto Rico, and his 6 children (3 daugh- ing their technique with fl uorescence fi rst Dasari Lecturer,” said Dr. Dasari. ters and 3 sons), and 9 grandchildren. Page 3 Research Report phase and appear on the high frequency Investigating the mechanism of side of the OH lineshape. The structural sensitivity of ω has been confi rmed by hydrogen bond exchange in wa- OH ter by ultrafast two-dimensional recent molecular dynamics (MD) simulations showing that ωOH is well correlated infrared spectroscopy with the oxygen-oxygen separation of a Sean T. Roberts1,2, Joseph J. Loparo1,2,3, and Andrei hydrogen bonded pair of molecules.3-5 Tokmakoff1,2 Moreover, the simulations found that ωOH 1 Department of Chemistry is best correlated with the projection onto 2 G.R. Harrison Spectroscopy Laboratory, the OH bond of the electric fi eld of the Massachusetts Institute of Technology, Cambridge, surrounding liquid located at the proton.3 Massachusetts, 02139-4037 This fi eld is due in large part to the near- 3 Present Address: Department of Biological est neighbor of the proton, showing that Chemistry and Molecular Pharmacology, Harvard ω is a strong probe of local structure. Medical School, Boston, Massachusetts, 02115 OH Previous measurements by our group Among liquids, water is exceedingly have characterized the time scales for the complex to describe because its ability to fl uctuations and reorganization of water’s form up to four hydrogen bonds results in hydrogen bonding network.6,7 The results an extended tetrahedral network of mol- of three-pulse echo peakshift (3PEPS) and ecules that is highly structured for a liq- polarization dependent pump probe mea- uid. Indeed, many of water’s anomalous surements are displayed in Fig. 1. Both properties, such as the lower density of ice measurements show initial fast decays relative to the liquid and its high heats of Figure 1: 1D plots showing the time scales for re- due to local fl uctuations about the proton organization of water’s hydrogen bonding network. melting and vaporization, are direct con- of HOD molecules followed by slower, A) 3PEPS measurement displaying an underdamped sequences of the time averaged structure long lived decays that are attributed to the hydrogen bond stretch. B) Pump probe anisotropy of water’s hydrogen bonding network. global reorganization of the liquid. In the capturing fast librational motion. From Ref. 6. Aqueous reactivity, however, is largely case of the 3PEPS measurement, which is drogen bonding partners and vice versa. dictated by the time dependent fl uctua- primarily sensitive to spectral diffusion, In practice, a 2D IR spectrum is obtained tions and distortions of this network. Wa- an initial 60-fs decay is followed by a re- by irradiating a sample with three input later has the ability to rapidly solvate na- currence at 160 fs due to an underdamped ser fi elds in a boxcar geometry. The signal scent charge because water molecules can O-H•••O stretching motion (hydrogen fi eld that is emitted into the fourth corner quickly rearrange their structure around bond vibration) that rapidly modulates of the box is then measured via interfero- a solute.1 Moreover, the transport of ex- ωOH. This is followed by a 1.2-ps decay metric detection using a known reference cess protons and proton holes, which ex- due to the global reorganization of the fi eld so that both the amplitude and phase hibit anomalously fast diffusion due to liquid, which includes the exchange of of the signal fi eld can be determined. In their ability to hop from one water mol- molecules into and out of the HOD sol- the experiments shown below, 2D IR ecule to another, is thought to be gated by vation shell. Likewise, the anisotropy surfaces of a ~1% HOD in D2O solution the formation and breakage of hydrogen measurement, which describes the reori- fl owed as a 50-μm thick liquid jet were 2 bonds. Unfortunately, a mechanistic un- entation of HOD molecules, shows a fast measured using 45-fs pulses centered at derstanding of the dynamics of water’s 50-fs decay due to intermolecular libra- 3400 cm-1. These pulses support enough hydrogen bonding network is lacking tions (hindered rotations) followed by dif- spectral bandwidth to span the broad OH largely because there are no structurally fusive reorientation on a 3-ps timescale. stretching lineshape as well as part of its sensitive experimental techniques with Although these experiments can mea- anharmonically shifted overtone. They the time resolution to resolve the fl uctua- sure the time scales for the evolution of were generated using a home built 3-μm tions of water’s hydrogen bond network. water’s structure, they cannot describe the OPA pumped by the output of a Femtolas- To monitor water’s evolving structure, underlying mechanism leading to these ers Femtopower Pro Ti:Sapphire multipass we employ ultrafast infrared spectroscopy changes because they average over all amplifi er. The output of the OPA is fed of the OH stretch of a solution of dilute hydrogen bonding environments. Two- into a Mach-Zehnder interferometer that HOD in D2O. The OH stretch is signifi - dimensional infrared-spectroscopy mea- splits the initial pulse into fi ve indepen- cantly broadened due to a distribution of surements (2D IR) do not average over dently controllable pulse replicas. Three hydrogen bonding structures present in the hydrogen bonding environments, and al- of the replicas form the boxcar used to ex- liquid. The formation of a strong hydro- low us to track how different hydrogen cite the sample: one acts as the reference gen bond results in a weakening of the OH bonding environments interconvert over fi eld used to detect the signal; one acts as force constant, and hence a large down- time. A 2D IR spectrum correlates how a tracer that follows the path traveled by shift (~500 cm-1) of the OH stretching a molecule at an initial frequency (ω1) the signal fi eld; one is used for the align- frequency, ωOH, relative to the gas phase evolves to a fi nal frequency (ω ) after a ment of detectors and is blocked during value of 3707 cm-1 occurs. Likewise, 3 given waiting time (τ2). By recording 2D the experiment. Specifi c details regard- molecules that only participate in weak or 8,9 spectra for a series of τ2 values, we can ing this setup are available elsewhere. broken hydrogen bonds are only slightly track how water molecules initially in non A waiting time series of 2D IR spectra -1 red shifted (~100 cm ) relative to gas hydrogen bonded confi gurations fi nd hy- Ultrafast, continues on page 6

Page 4 Research Report Tomographic phase microscopy Wonshik Choi1, Christopher Fang-Yen1, Kamran Badizadegan1,2, Seungeun Oh1, Niyom Lue1, Ram- achandra R. Dasari1, and Michael S. Feld1 1 G.R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139-4037 2 Department of Pathology, Harvard Medical School and Massachusetts General Hospital, Boston, Mass- sachusetts 02114 Introduction For visualizing transparent biological cells and tissues, the phase contrast microscope, with its related techniques, is the principal tool of nearly every cell biology laboratory. However, phase contrast methods are in- herently qualitative and lacking in 3-D imaging capability. We describe here a novel tomographic microscopy for quantitative Figure 1: Refractive index tomogram of a HeLa cell. (a) 3-D rendered image of a HeLa cell. The outermost layer of three-dimensional mapping of the refrac- the upper hemisphere of the cell is omitted to visualize the inner structure. Nucleoli are colored green and parts of tive index in live cells and tissues using cytoplasm with refractive index higher than 1.36 are colored red. The dotted box is a cube of side 20 μm. (b) Top view a phase-shifting laser-interferometric mi- of (a). (c)-(h) Slices of the tomogram at heights indicated in (a). Scale bar, 10 μm. The color bar indicates the refrac- croscope with variable illumination angle. tive index at λ= 633 nm. (i) and (j) Bright fi eld images for objective focus corresponding to (e) and (f), respectively. of projections of refractive index in mul- we take many angular projection phase Refractive index as an intrinsic tiple directions, in analogy to computed images over a wide range of angles, we source of contrast in light microscopy x-ray tomography in which the projection can reconstruct a 3-D map of refractive Although most biological cells and tis- of absorption is measured. Projections index of the sample with an algorithm sues exhibit negligible absorption under of refractive index have been performed similar to that used in x-ray tomography. visible light illumination, organelles show via a number of quantitative phase mi- In obtaining a set of angular projec- distinctive differences in refractive index, croscopy techniques, and earlier studies tions of phase images, we change the that amount to several percent of the mean used beam rotation4 or sample rotation5 direction of the illuminating beam rather refractive index. For this reason, in bio- to form tomographic images. However, than rotating the sample. This leaves the logical studies the refractive index can be one case provided no quantitative infor- sample unperturbed during the measure- a much better source of intrinsic contrast mation about the index of refraction,4 and ment, which is critical for a biological than absorption. the other required glycerol immersion of specimen, and enables a fast dynamic Local variations of refractive index in the sample and physical rotation of the study as well. A novel heterodyne laser the specimen induce different phase delays sample in a micropipette.5 interferometric microscopy7 quantita- from point to point in the fi eld of view. CT scan with biological cells and mul- tively images the phase delay induced by These are used to image and visualize bio- ticelluar organisms the sample, and a galvanometer scanning logical structures by such techniques as mirror changes the direction of illumina- phase-contrast microscopy, differential in- We have developed a technique for quanti- tion. Illumination angles are limited to terference-contrast (DIC) microscopy and tative, high-resolution 3-D measurements |θ|< 60 degrees by the numerical aper- quantitative phase microscopy.1-3 These of the refractive index of suspended or ture of condenser and objective lenses. techniques are sensitive enough to easily substrate-attached cells and multicellular It takes about 10 sec to cover the entire resolve the half-radian phase delay typi- organisms with no need for disturbing the range of angles in steps of 1.2 degree. 6 cally induced by a single cell. However, sample or immersing it in special media. To reconstruct a 3-D refractive index the phase delay is proportional to the prod- For near plane-wave illumination of tomogram from the projection phase im- uct of refractive index and path length or, a thin sample with small contrast of in- ages, we applied a procedure based on more generally, the convolution of the re- dex of refraction, the phase of the trans- the fi ltered back-projection method.8 A fractive index with the point spread func- mitted fi eld is to a good approximation discrete inverse Radon transform was ap- tion of the optical system. Thus, phase equal to the line integral of the refractive plied to every X-θ slice in the beam ro- microscopy techniques provide neither a index along the path of beam propaga- tation direction, with X the coordinate in 3-D image of the cell nor a 3-D map of the tion. Therefore, the phase image can be the tilt direction and θ the angle of the il- refractive index distribution. interpreted simply as the projection of luminating beam relatve to the optic axis One strategy for 3-D determination of refractive index, analogous to the projec- of the objective lens. An X-Z slice is re- refractive index is based on measurement tion of absorption in x-ray tomography. If Tomography, continues on page 6 Page 5 Tomography, continued from page 5 were paralyzed with 10 mM sodium Ultrafast, continued from page 4 azide in NGM buffer and imaged in the constructed from an X-θ slice. By merg- of HOD in D2O is shown in Fig. 2a. Two ing all the X-Z slices at every pixel in the same solution. Overlapping tomograms peaks appear in the spectrum, a positive Y-direction, we can get the 3-D map of were created and the resulting data as- peak centered along the diagonal axis due refractive index. To verify that our instru- sembled into a mosaic (Fig 2). Several to photobleach of the υ = 0 → 1 transi- ment can determine the refractive index internal structures are visible, including tion and a second anharmonically shifted with an accuracy of 0.001, we imaged a prominent pharynx and digestive tract. negative peak due to the photoinduced 10-μm polystyrene beads (Polysciences In summary, we have developed a technique for quantitative refractive index to- #17136, n=1.588 at λ=633 nm). We esti- =0fs =40fs mography of living cells and tissues. We A τ2 τ2 mate the spatial resolution of our tomog- 3600 raphy technique to be approximately 0.5 note that the 3-D structure mapped by to- μm in the transverse (x-y) directions and mographic phase microscopy can comple- 3400 0.75 μm in the longitudinal (z) direction. ment the images revealed by techniques 3200 We imaged single HeLa cells in culture such as hematoxylin and eosin staining. medium. Cells were dissociated from cul- Refractive index data can be used to study 3200 3400 3600 3200 3400 3600 light scattering properties of cells and tis- τ = 150 fs τ =80fs ture dishes and allowed to partially attach ) 2 2 to the coverslip substrate. A 3-D tomo- sues and characterize sample-induced ab- -1 3600 gram of the index of refraction of a single errations in microscopy. Characterization and correction of such aberrations may be 3400 cell (Fig. 1a,b) and x-y tomographic slices c(cm of the same cell at heights of z = 12, 9.5, particularly important for modern super- π 3200 /2 8.5, 7.5, 6.5 and 5.5 μm above the sub- resolution techniques such as STED and 3

ω 3200 3400 3600 3200 3400 3600 strate (Fig. 1c-h) show that the index of structured illumination microscopy. τ2 = 300 fs τ2 = 600 fs refraction is highly inhomogeneous, vary- Acknowledgements 3600 ing from 1.36 to 1.40. Bright ﬁ eld images This work was funded by the National 3400 for objective focus corresponding to Fig. Institutes of Health (P41-RR02594-18) 1e-f are shown in Fig. 1i-j, respectively. and Hamamatsu Corporation. 3200 There is a clear correspondence between the tomographic and bright ﬁ eld images References 3200 3400 3600 3200 3400 3600 -1 in terms of cell boundary, nuclear bound- 1. Fritz Zernike, Physica 9, 686 (1942). ω1/2πc(cm ) 2. A. Barty, K. A. Nugent, D. Paganin et al .,

ary, and size and shape of the nucleoli. ) 3550 Optics Letters 23 (11), 817 (1998). Note that the refractive index of the -1 3. T. Ikeda, G. Popescu, R. R. Dasari et al., 3500 B nucleus (n≈1.36), apart from the nucleo- Optics Letters 30 (10), 1165 (2005). (cm >

4. V. Lauer, J. Microsc. 205 (Pt 2), 165 (2002). 3 lus, is smaller than some parts of the cy- 3450 5. F. Charriere, A. Marian, F. Montfort et al., ω toplasm (n≈1.36-1.39) and that the refrac- < Opt. Lett. 31 (2), 178 (2006). 3400 tive index of the nucleoli, n≈1.38, is larger 6. W. Choi, C. Fang-Yen, K. Badizadegan et al., than that of the rest of the nucleus. This is Nat Methods (2007). contrary to the widely cited claims that the 7. C. Fang-Yen, S. Oh, Y. Park et al., Opt Lett 32 3350 refractive index of the nucleus as a whole (11), 1572 (2007). 8. A. C. Kak and M. Slaney, Principles of Com- 3300 9 0 200 400 600 is higher than that of the rest of the cell. puterized Tomographic Imaging. (Academic Similar results were obtained for cultured Press, New York, 1999). τ2 (fs) 9. A. Brunsting and P. F. Mullaney, Biophys. J. HEK 293 cells, B35 neuroblastoma cells, Figure 2: A) A waiting time series of 2D and primary rat hippocampal neurons. All 14 (6), 439 (1974). IR data for the OH stretch of dilute HOD in cells imaged contained many small cyto- D2O. B) The fi rst moments of vertical slices taken at ω = 3280 cm-1 and 3530 cm-1 as a function plasmic particles with high refractive in- 1 Dresselhaus wins of ω . From Ref. 11. dex. These particles may be lipid droplets, 2 lysosomes, vacuoles, or other organelles. 2008 Buckley Award absorption associated with the υ = 1 → To demonstrate tomographic imag- MIT Institute Professor and Spectroscopy 2 overtone transition. Various changes to ing of a multicellular organism, we im- Laboratory core researcher Mildred Dres- the surfaces signaling the loss of frequen- aged the nematode C. elegans. Worms selhaus is the 2008 recipient of the Oliver cy memory can be seen as τ2 increases, in- E. Buckley Condensed Matter Prize from cluding broadening of the surfaces along the American Physical Society. Profes- the anti-diagonal direction and a decrease sor Dresselhaus was cited, “for pioneer- of the slope of the node separating the ing contributions to the understanding of fundamental and overtone transitions. electronic properties of materials, espe- This loss of correlation can be quantifi ed cially novel forms of carbon.” The prize is by a number of different metrics,10 and named after Oliver H. Buckley, an infl u- the time scales for the loss of frequency ential president of Bell Labs, and the fi rst correlation agree well with the results Figure 2: Bright fi eld image (a) and slice of index 9 tomogram (b) of the nematode C. elegans. An- prize recipients were Nobel prize winners of our previous 3PEPS measurement. terior is to the right. Scale bar, 50 μm. The color William Shockley in 1953 and John Bar- More intriguing are the frequency de- bar indicates the refractive index at λ= 633 nm. deen in 1954. pendent changes to the 2D lineshape with Page 6 waiting time. Noticeably, the antidiagonal Phys. 118 (1), 264-72 (2003). linewidth for slices taken on the high fre- 5. K. B. Moller, R. Rey, and J. T. Hynes, J. Phys. Chem. A 108, 127-189 (2004). quency (blue) side of the 2D surface are 6. J. J. Loparo, C. J. Fecko, J. D. Eaves, S. T. nearly twice as large as those taken at the Roberts, & A. Tokmakoff, Phys. Rev. B 70, low frequency (red) side, indicating that 180201 (2004). hydrogen bonded and non hydrogen bond- 7. C. J. Fecko, J. J. Loparo, S. T. Roberts, and A. Tokmakoff, J. Chem. Phys. 122, 054506 ed molecules experience different fl uctua- (2005). 11 tions. Examining vertical slices taken 8. C. J. Fecko, J. J. Loparo, & A. Tokmakoff, on the blue (red) side of the lineshape as Opt. Commun. 241, 521 (2004). a function of τ corresponds to watching 9. J. J. Loparo, S. T. Roberts, & A. Tokmakoff, J. 2 Chem. Phys. 125, 194521 (2006). molecules in broken or weak (strong) hy- 10. S. T. Roberts, J. J. Loparo, & A. Tokmakoff, J. drogen bonds relax back to the band cen- Chem. Phys. 125, 084502 (2006). ter. Fig 2b. shows the fi rst moment for 11. J. J. Loparo, S. T. Roberts, & A. Tokmakoff, J. vertical slices taken at ω = 3280 cm-1 and Chem. Phys. 125, 194522 (2006). 1 12. F. H. Stillinger, Science 209 (4455), 451-57 3530 cm-1 as a function of τ . For slices Figure 3: Snapshots from a 288-fs sequence in 2 which a water molecule (bottom) exchanges hydro- (1980). taken on the red side of the lineshape, a gen bonding partners (upper left: original hydrogen 13. D. Laage & J. T. Hynes, Science 311, 833-35 recurrence is seen which corresponds to bond acceptor, upper right: new hydrogen bond ac- (2006). the hydrogen bond vibration seen in our ceptor). Hydrogen bonds are color coded, and illus- 14. A. Tokmakoff, Science 317, 54-55 (2007). previous 3PEPS measurement. However, trate the rotation from the initial geometry (blue) to a bifurcated state (green) and fi nall to a new hydro- Dasari Spectroscopy Lab- slices on the blue side of the lineshape gen bonded confi guration (orange). From Ref. 14. quickly relax to band center within 100 fs. oratory Lectureship This relaxation rate is faster than the char- ecule on the left, the molecule on the right acteristic time scale for the intermolecu- slides toward the exchanging molecule to lar motions of the liquid (~200 fs) which form a new hydrogen bond. The amount strongly suggests that confi gurations cor- of time the exchanging molecule spends responding to broken hydrogen bonds are as a “broken hydrogen bond” is minimal. created by transient fl uctuations of the liq- The experiments described above allow uid and do not occupy a stable minimum us to gain a glimpse of water’s rapidly on water’s free-energy surface. Moreover, evolving structure. The results of these the ~60-fs decay of the fi rst moment for experiments indicate that stable dangling

ω1 slices on the blue side suggests that it hydrogen bonds are exceedingly rare in is most likely librations that shuttle water aqueous solution. This supports a pic- molecules in and out of hydrogen bonds. ture within which water molecules that The hypothesis that hydrogen bond re- break a hydrogen bond quickly reorient arrangement involves the concerted mo- to a new hydrogen bonding partner by the In honor of the contributions of Ramach- tion of water molecules is not a new one. concerted motion of multiple molecules. andra Rao Dasari an endowed fund, the It dates back to Stillinger, who coined Currently, we are working to further test Dasari Spectroscopy Laboratory Lecture- such a mechanism as a “switching of al- this hypothesis by measuring a 2D IR an- ship, has been established at MIT. This 12 legiances.” However, there has been isotropy that will allow us to determine if fund will support an annual event in which little experimental work to confi rm this there is any frequency dependence to the a prominent scientist associated with the hypothesis. Evidence in support of this reorientation of water molecules. Also, Spectroscopy Laboratory presents a lecture mechanism comes from recent MD simu- we are currently exploring how the fl uc- at MIT. Income from the endowment will 13 lation work by the Hynes group whose tuations of water’s hydrogen bonding net- be used for travel expenses, an honorari- fi ndings suggest that hydrogen bond ex- work infl uence the transport of protons in um, and a dinner in honor of the speaker. change is initiated when a hydrogen bond alkaline solution. Ramachandra Rao Dasari was born and acceptor becomes overcoordinated and a educated in India. He joined the Physics nearby potential hydrogen bond acceptor Acknowledgements faculty at the Indian Institute of Technol- is undercoordinated. Once this occurs, This work was supported by the Depart- ogy, Kanpur in 1962. Ramachandra came a water molecule bound to the overcoor- ment of Energy, the MIT Laser Research to MIT in 1966 as a fellow for two years dinated molecule can break its hydrogen Facility, and the David and Lucile Packard working in the newly formed group of bond and form a new one to the underco- Foundation. Charles Townes and Ali Javan. He subse- ordinated molecule via a large amplitude quently returned to IIT-K and collaborated rotation. An illustration of this mecha- References with Putcha Venkateswarlu to build one of nism is displayed in Fig. 3, which shows 1. R. Jimenez, G. R. Fleming, P. V. Kumar, & M. the largest laser laboratories for university snapshots during a hydrogen bond ex- Maroncelli, Nature 369, 471-73 (1994). research in India. During his 17 years at change event taken from a classical MD 2. H. Lapid, N. Agmon, M. K. Petersen, & G. A. IIT-K, Ramachandra trained a large num- Voth, J. Chem. Phys. 122, 014506 (2005). simulation employing the SPC/E water ber of Ph.D. students and established re- potential.14 As the water molecule pic- 3. C. J. Fecko, J. D. Eaves, J. J. Loparo, A. Tokmakoff, & P. L. Geissler, Science 301, lationships between IIT-K and several tured on the bottom of the fi gure rotates 1698-702 (2003). national laboratories. As a physics panel one of its OH bonds away from the mol- 4. C. P. Lawrence & J. L. Skinner, J. Chem. Dasari, continues on page 15

Page 7 Seminar on Modern Optics and Spectroscopy Fall Semester 2007

September 25 Changhuei Yang, California Institute of Technology Lighting ways in biomedicine

October 2 David Snoke, University of Pittsburgh Bose-Einstein condensation of polaritons in microcavities

October 9 1st Annual Dasari Lecture Charles Townes, University of California Berkeley The fun of a physics career

October 16 Federico Capasso, Harvard University Advances in quantum cascade lasers

November 6 Stephen Coy, Sionex Corporation The power of differential ion mobility

November 13 Richard Averitt, Boston University Active terahertz metamaterials

November 20 Obrad Scepanovic, MIT Multimodal spectroscopy of vulnerable plaque

November 27 Charles Lin, Massachusetts General Hospital In vivo cell tracking

December 4 David De Mille, Yale University Ultracold molecules

December 11 Hyunbin Son, MIT Raman spectroscopy of single-wall carbon nanotubes

Tuesdays, 12:00 - 1:00 p.m., Grier Room (34-401) Refreshments served following the seminar. Sponsored by the George R. Harrison Spectroscopy Laboratory, Department of Electrical Engineering and Computer Science, and School of Science, MIT Lester Wolfe Workshop in Laser Biomedicine Frontiers in Modern Microscopy

Tuesday, November 20, 2007, 1:00-6:00 pm Massachusetts Institute of Technology Grier Room 34-401 50 Vassar St, Cambridge, MA

Making light work in microscopy Tony Wilson, Oxford University

Field-based tomographic microscopy Wonshik Choi, Massachusetts Institute of Technology

Imaging cellular structures and molecules with X-ray tomography Carolyn Larabell, UCSF and Lawrence Berkeley National Laboratory

Super-resolution optical microscopy with STORM Xiaowei Zhuang, Harvard University and Howard Hughes Medical Institute

3D Optical coherence phase microscopy Johannes de Boer, Massachusetts General Hospital

STED microscopy Katrin Willig, Max Planck Institute for biophysical Chemistry, Göttingen

Nonlinear microscopy in local optical fields Katrin Kneipp, Harvard University Medical School and Massachusetts General Hospital

Refreshments served at 3:30 pm

Sponsored by: G. R. Harrison Spectroscopy Laboratory, MIT Massachusetts General Hospital Wellman Center for Photomedicine Harvard-MIT Division of Health Sciences and Technology and Center for the Integration of Medicine and Innovative Technology

PLEASE POST PLEASE POST DASARIFEST 2007 July 14 and 15, 2007 colleagues, friends, family, and admirers celebrated Ramachandra Dasari’s 75th birthday and his 27 years as As- sociate Director of the Spectroscopy Laboratory with a symposium, dinner, and a birthday party.

Ramachandra at the symposium in his honor

Suhasini, Ramachandra, and family

Mike Otteson applauds The Spectratones: (L to R) Gajendra Singh, Seungeun Oh, Michael Feld, Obrad Scepanovic, Zoya Volynskaya, Geoff O’Donoghue, Kate Bechtel, Gabi Popescu, and Alison Hearn L to R: Michael Feld, Obrad Scepanovic, and Kate Bechtel empower Ramachandra with a bullhorn. Suhasini admires his spectrograph, custom-made by Seungeun Oh.

Ramachandra in cap of honor sharing garlands with Suhasini Suhasini, Lakshmi, and Ramachandra with the Putcha family

L to R: Kamran Badizadegan, Ramachan- dra, N.R. Desai, Ali Javan, Gabi Popescu, Alison Hearn, and Michael Feld.

Ramachandra with symposium speakers (L to R): Abi Haka, N.R. Desai, John Thomas, Jason Motz, Obrad Scepanovic, Richard Rava, Greg Schimkaveg, Ramachandra with friend and mentor Ali Javan Takeshi Oka, Condon Lau, and Yongkeun Park

Page 11 PLEASE POST Director’s Perspective uscripts” “submitted” to The Spectro- newspaper or magazine article, or wher- ever does not constitute prior publication.” Should The Spectrograph feature graph for “consideration” to be published. The science community has long strug- While recognizing that online availabil- original scientifi c research? gled to fi nd the right balance between dis- ity of The Spectrograph is a concern for By Michael S. Feld seminating preprints of scientifi c research some editors and editorial boards, I urge the OSA to clarify its policy on prior pub- Our newsletter, The Spectrograph, has a and avoiding duplicate publication and lications and to provide suffi cient detail to longstanding tradition of featuring current, self-plagiarism. There is nearly unanimous prevent ad hoc interpretation of its poli- original scientifi c research by its faculty agreement that detailed presentation of un- cies by individual editors or reviewers. In and affi liates. These articles keep current published data in scientifi c meetings does addition, as a Fellow of the OSA, I call on and former colleagues, affi liates, advisors, not constitute prior publication, but there the Society not to reduce the free exchange and friends of the G. R. Harrison Spec- is no consensus or clarity regarding non- of scientifi c information by limiting long- troscopy Laboratory abreast of our most peer-reviewed distribution of original data standing, traditional ways by which we recent advances and current directions. In in newsletter, laboratory websites, or even disseminate and discuss preprint research addition, such articles help to accomplish well-known and respected preprint serv- data in our discipline. the dissemination of our scientifi c advanc- ers that have a long tradition in the fi eld of es as mandated by NIH for resources such physics. While the OSA guidelines cited Laser Biomedical Research as our MIT Laser Biomedical Research above do not address these issues at all, Center. The Spectrograph has never ex- other scientifi c societies take somewhat Center outside projects plicitly or implicitly suggested that these contradictory positions. The American As- The Laser Biomedical Research Center research reports are peer-reviewed or in- sociation for the Advancement of Science (LBRC) encourages outside projects in dexed publications, and neither the Spec- clearly warns that “posting of a paper on various areas of laser biomedicine. The troscopy Laboratory nor MIT holds copy- the Internet may be considered prior pub- facilities of the LBRC, along with techni- right on them. Nevertheless, one of our lication that could compromise the origi- cal and scientifi c support, are made avail- recent manuscripts was rejected by an Op- nality of the Science submission, although able on a time-shared basis free-of-cost to tical Society of America (OSA) publica- we do allow posting on not-for-profi t pre- qualifi ed scientists, engineers and physi- tion largely on the basis of the claim that print servers in many cases” (http://www. cians throughout the United States. Re- some of the research fi ndings had been sciencemag.org/about/authors/faq/index. searchers use the LBRC’s resources to ex- previously published in The Spectrograph. dtl, accessed on 10/21/07). While most ploit laser-based spectroscopic techniques I emphatically share the concerns of journals such as Science and Nature ac- for medical applications such as the spec- the OSA Board of Editors about duplicate cept preprint dissemination of research tral diagnosis of disease, investigation of data in recognized preprint servers, other biophysical and biochemical properties “...I urge the OSA to clarify societies such as the American Physiolog- of cells and tissues, and development of its policy on prior publica- ical Society take a much more strict posi- novel imaging techniques. For example, tion that “widely circulated, copyrighted, ongoing collaborations are using spectro- tions and... to prevent ad or archival reports, such as the technical scopic instruments developed at the LBRC hoc interpretation of its pol- reports of IBM, the preliminary reports of to optically determine elastic properties of MIT, the institute reports of the US Army, self-assembling biological springs. In an- icies...” or the internal reports of NASA” all con- other collaborative study, researchers are publications and self-plagiarism, but I stitute prior publication (http://www.the- assessing sampling volume and thereby strongly disagree that publication of pre- aps.org/publications/journals/apsethic. the purity content of pharmaceutical tab- liminary research fi ndings in The Spectro- htm, accessed on 10/21/07). In contrast, lets using integrating sphere facilities. graph constitutes prior or duplicate pub- the American Physical Society (APS) Outside projects can be initiated by con- lication. The OSA clearly indicates that a places the primary emphasis on peer-re- tacting Ramachandra Dasari, Associate “manuscript must contain signifi cant new view and states that “manuscripts sub- Director of the Spectroscopy Laboratory. content not previously published or submitted to the journals must contain origi- Once the scope of the project is defi ned, mitted elsewhere for simultaneous consid- nal work which has not been previously a Research Project Application must be eration” (http://josaa.osa.org/submit/re- published in a peer-reviewed journal, and fi lled out. Proposals must be concise and view/ethical_guidelines.pdf, accessed on which is not currently being considered are evaluated by members of the LBRC’s 10/21/07). Furthermore, in an open letter for publication elsewhere” (http://authors. scientifi c staff on the basis of scientifi c to colleagues, the OSA Board of Editors aps.org/esubs/guidelines.html accessed merit, originality, potential signifi cance clearly states that “duplicate submission on 10/21/07). Similarly, the National and compatibility with available equip- is the submission of substantially similar Academy of Sciences considers bodies of ment. The review process is rapid, and papers to more than one journal” and that work previously published if “they have applicants are promptly notifi ed of the de- “self-plagiarism is the publication of sub- appeared in suffi cient detail to allow rep- cisions. Participation of researchers from stantially similar scientifi c content of one’s lication, are publicly accessible with a the small business community and from own in the same or different journals” fi xed content, and have been validated by colleges, universities and hospitals that (http://josaa.osa.org/submit/review/pla- review” (PNAS, Vol. 96, Issue 8, 4215, have limited research facilities is encour- giarism_2005.pdf, accessed on 10/21/07). 1999). Specifi cally, the PNAS editorial aged. For further details visit the website The Spectrograph neither meets the defi ni- policies state that “a summary of work in at: http://web.mit.edu/spectroscopy/facili- tion of a scientifi c “journal” nor are “man- a review, a perspective, a commentary, a ties/guideline.html#Application. Page 13 Spectral Lines ten years he was heavily involved in the child on each step.” More than a burner study of gases. Then Bunsen’s studies What about that famous burner? The by Stephen R. Wilk evolved around galvanic batteries, and he one he used for his spectroscopic work, Textron Defense Systems invented the Bunsen battery, which used and with which he impressed his stu- Cambridge, MA inexpensive carbon in place of platinum dents by holding his hand in it, G. Gor- or copper as the negative pole. He used don Liddy-like? Some people claim that this in electrochemistry, producing so- he didn’t invent it – that his technician dium, aluminum, and other metals from did, or that he adapted it from Faraday, or their chlorides. that ironically in some other way he has His work in spectroscopy, our reason been credited with one thing that he really for covering his work, did not begin until didn’t have much to do with. But Bunsen comparatively late, in the 1860s. He and was reported to be a superb experimental- his younger protégé Gustav Kirchhoff ob- ist, who invented the Bunsen battery, a served the colors and spectra of chemical much improved eudiometer for gas mea- salts, heated using an alcohol fl ame or a surements, the grease-spot photometer burner fl ame. They also observed that for light measurements, the highly sensi- Stephen R. Wilk placing such a fl ame in a white light led tive spectrometer he and Kirchhoff used to dark absorption bands. In addition, they in their measurements, an ice calorimeter, Several years ago I ran across a cartoon produced spectra in the electrical spark a vapor calorimeter, a thermopile, and a by Sidney Harris, the scientifi cally-ori- discharge of a Ruhmkorff coil with a vacuum pump. He stressed the importance ented artist whose work appears in ven- small sample of the material under test ap- of building one’s own experimental appa- ues such as American Scientist and Sci- plied to its electrodes. Both the light and ratus to his students and complained when entifi c American. It shows an obviously dark bands were characteristic of the me- they did not achieve profi ciency at glass- 19th century scene of a man in a top hat tallic part of the salt, they found, and the blowing. addressing another man at a table. “Bun- test was sensitive enough to require only All of which supports the notion that sen,” says the top-hatted man, “I must tell a tiny amount of the test he improved the burner you how excellent your study of chemical material although it had ...(Bunsen) was reputed to achieve the one that spectroscopy is, as is your pioneer work to be highly purifi ed to to have tough skin on his now bears his name. in photochemistry – but what really im- produce only the charac- hands, as he demonstrat- Gas burners using the presses me is that cute little burner you’ve teristic lines. They were ed by holding his hand in newly-available coal come up with.” able to identify cesium the fl ame of his burner gas had been built by I was amazed. I have to admit that all I and rubidium from ex- Michael Faraday in really knew about Bunsen was that burner tremely small samples; and removing the lids England and by Aimé – I didn’t even know his full name. I’d subsequently they iso- of hot crucibles with his Argand in Switzerland, used that natural gas burner in college and lated larger quantities bare hands... which had a system of high school, and (with uncles and cousins of the elements by more delivering the gas for in chemistry) I knew of it well before that. conventional means. lighting before Germany did. Bunsen did But I never gave a thought to Bunsen’s Bunsen was a dedicated teacher, lectur- not invent the gas burner, but I doubt if real work. This cartoon was the fi rst I’d ing for 100 hours each year through sev- anyone ever claimed that he did. The gas heard of Bunsen as a spectroscopist or enty four semesters. He designed and built system that came to operate in Germany electrochemist. his own apparatus and was particularly apparently did not have the same fl ow So what is the story on Bunsen, and skilled at glassblowing. He was reputed to rate as in England. Henry Roscoe, one what does he really have to do with that have tough skin on his hands, as he used of Bunsen’s English students, brought a burner? to demonstrate by holding his hand in the lamp called a “gauze burner” to Heidel- Robert Wilhelm Bunsen was born in fl ame of his burner, and by removing the berg, but at low fl ows it tended to go out. 1811 in Göttingen, Germany, the youngest lids of hot crucibles with his bare hands. Bunsen experimented with different tube of the four sons of Christian Bunsen, pro- Bunsen never married. The story diameters, aided by his laboratory assis- fessor of philology at the university there. (probably not true) was told that, while a tant, Peter Desaga, fi nally coming up with Robert studied chemistry at Holzminden young man at Marburg, he had proposed something very much like the present-day and Göttingen, then toured European lab- to a young woman and had his suit ac- “Bunsen Burners”, although it lacked the oratories for three years before returning cepted, but he got so absorbed in his study rotating ring that adjusted the fl ow of air to his home town to be a lecturer at the of cacodyl that he neglected to visit her to the fl ame. University of Göttingen before going on for several weeks and became uncertain But the burner Bunsen and Desaga to positions at Kassel, Marburg, and fi - whether or not he had actually proposed. modifi ed did what it needed to do – it nally Heidelberg. He visited her without apologizing for his provided a colorless, sootless fl ame that He made a false start in organic chem- absence and re-proposed with predict- was ideal for spectroscopic work and istry, doing work on the arsenical com- able results. Years later, Kirchhoff’s wife general laboratory applications. Bunsen pound cacodyl, but soon settled in inor- asked Bunsen why he had never married. himself did not patent the device. Desaga ganic chemistry. He lost an eye due to an “Heaven forbid,” he replied, “When I re- built many copies for the laboratory, then, explosion of cacodyl cyanide. For about turn at night, I should fi nd an unwashed with Bunsen’s approval, he built more for Page 14 Dasari Lectureship, continued from page 3 the fi rst time; and at MIT, fi rst measurement of laser frequencies in the far infra- member of the University Grants Com- red; very high resolution study of N2 laser mission, he helped initiate new programs, transitions, the detection of anisotropy of including teacher training workshops, to gamma rays emitted from optically pumped improve undergraduate education. radioactive rubidium atoms and develop- In 1979 Ramachandra, his wife Suhas- ment of the Laboratory’s Raman facili- ini and his children moved to Canada to ties for biological and physical sciences. spend a year each at the National Research His other contributions include oversee- Council, Ottawa, and the University of ing project and facility development at the British Columbia, Vancouver. Since 1980 MIT Laser Biomedical Research Center, Ramachandra has been Associate Direc- an NIH biomedical resource, and the MIT tor of the MIT Spectroscopy Laboratory. Laser Research Facility, a physical sci- Some highlights of his research are: at ence resource. Ramachandra is a confi dant IIT-K, observing the fi rst electronic spec- A diagram of a bunsen battery to Spectroscopy Laboratory graduate stu- trum of NSe and devising a new method dents and professors, a project organizer sale to other laboratories, calling them for obtaining laser emission in copper va- “Bunsen’s Burners”, and defending them and a troubleshooter. He is always there por laser; at NRC, Canada, observing the when needed. against others who tried to fi le patents on Dicke narrowing in infrared transitions for the device. Desaga’s family continued in the scientifi c instrument business, and was still Answers to last issue’s crossword manufacturing the burners into the 1950s. The winner of the Spring 2007 Spectrograph crossword challenge was Kate Bechtel! The fi rm is still in business, but a perusal The winner of this issue’s challenge will be published in the Spring 2008 issue of The of its website fails to turn up any of the Spectrograph. burners, many of which seem to be manu- factured in Asia today. In the modern lab- Look for an interactive version of The Spectrograph crossword puzzle online at http:// oratory the burner uses not coal gas (made web.mit.edu/newsoffi ce/2006/FamousOpticsPeople.html by heating coal or coke in air, producing a mixture which was about 50% hydrogen, G with additions of carbon dioxide, carbon monoxide, methane, and nitrogen, the I DIFFR ACT I VE proportions depending upon the process M N used), but natural gas (methane, mostly, R A B MU L T I OR DER but with other gases present, including P E D E S T A L E butane, propane, carbon dioxide, nitrogen, hydrogen sulfi de, and even helium). That F P L Q UAR TER TWENTY it was able to make the change is a for- L H F I tuitous tribute to the man’s inventiveness, E E E G C A guaranteeing that his name would live on, even among people unaware of his many C R P R H L Z B other and arguably more signifi cant ac- T W I N D O W NEUTR ALDENS I TY complishments. I C S N T M R O R V ME TR IC C H P O R A References E K O E I O P N 1. On Robert Bunsen, see Dictionary of Sci- entifi c Biography, Volume II, pp. 586-590 T I L T T R R T S Scribner’s, 1970; Physics Education 34(5) 321-326 (1999), the Wikipedia entry at N BEAMSPL I TTER D I L http://en.wikipedia.org/wiki/Robert_Bun- E A T Y E O A sen, and, most especially, J. Chem. Ed. 4 (4) 431-439 (1927), for which the author inter- M L I DETECTOR N T viewed some of Bunsen’s former students. A L O W I 2. On the place of Bunsen and Kirchhoff in the history of spectroscopy, see William McGucken’s T D N ACHR OMA T I C O Ninetheenth Century Spectroscopy, Johns Hopkins Press, 1969, especially pp. 26-31. I R I O N 3. The history of the Bunsen Burner gets treated at C Y L I N D R ICAL R A irregular intervals in The Journal of Chemical V R T Education. See J. Chem. Ed. 9 1963-1969 (1932); 27(9) 514-515 (1950); 33 (1) 20-22 (1956); 77 S P H E R ICAL O P R ISM (5) 558-559 (2000); 82 (4) 518 (2005). See also R R N http://en.wikipedia.org/wiki/Bunsen_burner. G Page 15 The Back Page

It pays to enrich your cell power!

These nine images, all transmission electron micrographs, show some classical cellular features. Magnifi cation varies from image to image, but the features shown are all readily identifi able based on their distinctive shape and surroundings. Nevertheless, you may refer to the following clues to make sure you are on the right track. 1. These beads on a string (arrowheads) are brilliant translators of the genetic code. 2. Elmer’s and Velcro are no match for this intercellular junction! 3. Their 9+2 arrangement of microtubules is reminiscent of centrosomes, but these apical membrane specializations are ideal transducers of mechanical force to or from the cell. 4. This delicate stack of membranes (crescent shaped, roughly between 11 and 4 o’clock) does as good a job in sorting, packaging and delivery as the Fed Ex! 5. Yet another precious gift from your mom! 6. All about surface area. 7. These membrane-bound structures can wreak havoc on your diffuse refl ectance! 8. This giant organelle (occupying most of the image from 2 to 8 o’clock) is home to the structure shown in image 9. 9. Often considered an amorphous ball of stuff, this small organelle (~0.5-1.5 microns in size) often exhibits detailed internal structures.

MASSACHUSETTS INSTITUTE OF TECHNOLOGY Nonproﬁ t Organization G. R. HARRISON SPECTROSCOPY LABORATORY US Postage CAMBRIDGE, MA 02139-4307 PAID Cambridge, MA Permit No. 54016

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