DOCSLIB.ORG

Lecture 13: Laser-Induced Fluorescence: Two-Level Model

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lecture 13: Laser-Induced Fluorescence: Two-Level Model Lecture 13: Laser-Induced Fluorescence: Two-Level Model 1. Introduction and background Laser-Induced Fluorescence 2. Typical experimental setup 3. Signal level (steady & pulsed) Possible collisional change 4. Two-level model 2 LIF 5. Detection limits (pulsed laser) hν (spont. emission) 6. Characteristic times Laser absorption 7. Modifications to two-level model 1 1. Introduction What is Laser-Induced Fluorescence (LIF)? Laser-induced spontaneous emission Multi-step process: absorption followed by emission (fluorescence) Possible collisional change This is the laser- 2 induced fluorescence hν (spont. Emission) = LIF signal Laser absorption (pulsed or CW laser) 1 Notes . May occur from multiple states . Not instantaneous 2 1. Introduction Why is LIF of interest? o The LIF signal can be monitored at 90 to the exciting laser beam, thereby gives spatial resolution to the absorption measurement The signal rides on a dark background, rather than being based on signal differences as in absorption Species specific, and much stronger than Raman scattering Volume element = A·L (~1mm3) L Waist LIF Trans. Int. Ω l Collection optics d λexc • Signal for scanned- LIF 3 1. Introduction LIF can be used to monitor multiple gas properties including ni (n,v,J) number density of species i in a state described by n, v, and J T temperature (from the Boltzmann fraction) χi species concentration P pressure (from line broadening) v velocity (from the Doppler shift of the absorption frequency) And species including Radicals: OH, C2, CN, NH, … Stable diatoms: O2, NO, CO, I2, … Polyatomics: NO2, NCO, CO2, Acetone (CH3COCH3), Biacetyl ((CH3CO)2), Toluene (C7H8), and other carbonyls and aromatic compounds As well as many atoms…. 4 1. Introduction Absorption LIF Possible collisional 2 change 2 LIF Laser absorption hν (spont. emission) 1 Laser absorption 1 NOT instantaneous Instantaneous Multi-step process: absorption followed Single-step process after some delay by spontaneous emission Line-of-sight Typically 90o to the excitation laser beam Based on incident/transmitted Rides on a dark background signal difference Absorption and LIF can be performed with either CW or pulsed lasers 5 1. Introduction History & Some Key Accomplishments Flash-lamp pumped dye laser (Schafer, 1966) Tunable CW dye laser (1970) CW-doubled ring dye laser (1980) Nd-YAG and excimer-pumped dye lasers (1980) CW -scanned LIF (1980s) First PLIF imaging in laminar combustion (1982), turbulent (1984) Single-laser-pulse PLIF imaging of NO, T, and velocity (1989) OH PLIF in Identification of ketone tracers for PLIF imaging (1991) laminar flame M>1 Combustion: NO, T imaging (1993), OH imaging (1996) Extension of PLIF to high pressure/temperature (1993-2005) PLIF with vibrational transitions (IR-PLIF) (2000) Pulse-burst PLIF (2000) UV- PLIF of CO (2004) 2 OH PLIF in High-speed PLIF (2005) spray flame CW PLIF (2009) 6 2. Typical Experimental Setup Typical experimental setup for LIF systems Volume element Experiment (e.g. flame, flow, plasma) Excitation λex (~1mm3) Laser Trap or powermeter Ω l Collection optics d PMT with spectral filter to record emission at λex or at λdet (≠ λex), or grating monochromator Recording modes to disperse the spectrum 1. Emission intensity at a fixed detection wavelength 2. Fluorescence spectrum (spectrometer) I 3. Excitation spectrum (scanned laser) Pulsed laser 4. Can be extended to 2-d with CCD LIF (decay rate array detector (PLIF) contains info on “quenching rate” 5. Can also measure temporal behavior 7 2. Typical Experimental Setup Measurement volume Volume element 3 = A·L (~1mm ) L Waist Area = A Ω l Collection optics d . Pathlength: L ≈ 0.5 – 5mm lens area . Solid angle of collection: Note: 2 l At f # = 2.5, Ω/4π = 0.01, d 2 / 4 1 or 1%. Collection process is l 2 f # 2 relatively inefficient, even for l fast lenses. f # of collection: f # d 8 3. Signal Level Spontaneous emission corresponds to a decay in energy 2 Spontaneous Emission A21 1 Steady conditions S 21# photons/sec N A n V A F 2 21 4 2 21 4 N2 = # molecules in the measurement volume in state 2 n2 = number density of molecules (#/cc) in state 2 V = volume (cc) A21 = probability/sec of emission from state 2 to state 1 Ω/4π = collection fraction 21 SF power collected SF # photons/sech S21 F ∴ The LIF signal depends on constants and n2. Hence, the challenge of LIF is to find a way of specifying n2 quantitatively 9 3. Signal Level Spontaneous emission corresponds to a decay in energy 2 Spontaneous Emission A21 1 Pulsed conditions For unsteady conditions (e.g., short times or pulsed excitation): 21 SF # photons n2 t dtV A21 0 4 n2(t) depends on the laser and the collision process (further explained later) 10 4. Two-level Model Entry-level model for LIF (two levels) Induced Induced Collisional Collisional Fluorescence Absorption Emission Excitation De-Excitation 2 Energy n1W12 n2W21 n1Q12 n2Q21 n2A21 1 negligible “quenching” B12 I d Einstein theory prob/sec12 B12 d d 1 I / c Let B12 B12 / c 11 4. Two-level Model Entry-level model for LIF (two levels) -1 Iν Laser (~0.5cm FWHM) for typical pulses Most pulsed lasers are spectrally broad compared ν0 ν with absorption lines Iν ≈ constant over abs. line Absorption line (~0.1cm-1 at STP) Rate12 n1 B12 I d n1B12 I n1W12 Probability per second of line absorption per unit spectral Rate (s-1) that individual molecules in intensity: state 1 undergo the transition to state 2 B12 B12 / c Rate analysis n2 n1I B12 n2 I B21 Q21 A21 S.S. W12 n2 SS n1 n1W12 n2 W21 Q21 A21 W21 Q21 A21 n2 0 So now we have a solution for n ! 2 12 4. Two-level Model Entry level model for LIF (two levels) W12 n2 SS n1 W21 Q21 A21 Two limits emerge from the steady-state analysis for n2: Weak excitation (“linear LIF”) Strong excitation (“saturated LIF”) Weak excitation limit: Induced emission from level 2 much weaker than the sum of collisional and spontaneous decay processes g1B12 g2 B21 W B I A Q 21 21 21 21 g1W12 g2W21 0 0 0 0 Then n 2 n 1 , andn1 n1 (usually n 1 n where n is the conserved total 0 number density,n n1 n2 ) 0 W12 n2 n1 A21 Q21 13 4. Two-level Model Weak excitation limit Fluorescence signal SF n2 V A21 photons/s in weak excitation limit 4 A 0 21 n1V W12 B12 I A21 Q21 4 photons absorbed/sec "fluor. yield" fraction collected Notes: 0 1. To find n 1, need to know Q21 (rate of the electronic quenching, a collisional process), A21, Iν, and 0 2. SF n1 ni fv,J T LIF is directly proportional to the population density in the lower quantum level LIF is typically viewed as a species diagnostic 3. Alternative view: # of absorptions/sec # molec in 1prob/s of abs 0 n1V B12 I 14 4. Two-level Model Consider the saturation limit Induced emission rate >> collisional and spontaneous emission rates W21 A21 Q21 . Recall: g1B12 g2 B21 W12 B12 g2 n2 n1 n1 n1 W B g so g1W12 g2W21 Notes: 21 21 1 1. If g2 = g1, then n2 = n1, when the transition is “saturated” 0 0 0 n1 n1 2. n1 total n1 n2 n2 when g2 g1 1 g1 / g2 2 Fluorescence signal 0 g S n 2 V A photons/s in saturation limit F 1 21 g1 g2 4 Virtue: does not depend on Q21, laser intensity Complication: may be difficult to reach the saturation limit in all parts of the laser beam If intensity not sufficiently high, may reach intermediate situation between weak excitation and saturation 15 4. Two-level Model Intermediate result W 12 1 n2 SS n1 0 B Q A W21 Q21 A21 12 21 21 n2 n1 1 0 B12 B21 B12 B21 I with n1 n2 n1 g1B12 g2 B21 B12 /B12 B21 g2 / g1 g2 S n 1 F 2 S n Q A F ,sat 2,sat 1 21 21 B12 B21 I 16 4. Two-level Model Typical values for A and Q in electronic transitions 5 8 -1 6 -1 8 -1 1. A21 ≈ 10 ~ 10 s (10 s for NO, OH; 10 s for Na) Q Zcollision frequency OH 2. 21 Note: A21 / Q21 P1atm,comb. T 2 n c 8kT / ~ 106 s1 /1010 s1 2 P / T ~ 104 9 10 1 A small number! Q21 10 10 s at STP 3. Fluorescence yield = A21/(A21+Q21) << 1 except at low P LIF is an inefficient process! 4. Spontaneous emission for IR is much weaker (smaller A21) than UV LIF is weaker in the IR, unless Q21 is small (as may be the case!) A21,IR / A21,UV 1 Q / Q ? 21,IR 21,UV 17 4. Two-level Model Typical values for A and Q in electronic transitions 5. What is Iν for B21Iν >>A21+Q21? Call this (Iν)sat . For low Q21, Iν,sat >>A21/B21 I P / T 1/ B . For high Q21, Iν,sat >>Q21/B21 so that ,sat 21 3 3 I B . B A /8h B B 21 A 21 21 21 21 c 21 8hc 2 @ λ = 500nm, B21 25A21cm /erg s 4 10 -1 6 -1 . Assume Q21 ≈ 10 A21 (e.g., Q21 = 10 s , A21 = 10 s ) 4 I ,sat 10 A21 / 25A21 erg/s 400 ergs/cm2 cm2 Hz 0.4 J/m2 18 4. Two-level Model Typical values for A and Q in electronic transitions - continued 5. What is Iν for B21Iν >>A21+Q21? Call this (Iν)sat Power -1 10 -1 .
Load more

Recommended publications
  • A Rhodamine-Binding Aptamer for Super-Resolution RNA Imaging
    bioRxiv preprint doi: https://doi.org/10.1101/2020.03.12.988782; this version posted March 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. RhoBAST - a rhodamine-binding aptamer for super-resolution RNA imaging Murat Sunbul1*, Jens Lackner2, Annabell Martin1, Daniel Englert1, Benjamin Hacene2, Karin Nienhaus2, G. Ulrich Nienhaus2,3,4,5, and Andres Jäschke1* 1 Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg University, D-69120 Heidelberg, Germany 2 Institute of Applied Physics (APH), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany 3 Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany 4 Institute of Biological and Chemical Systems (IBCS), Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany 5 Department of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States Abstract RhoBAST is a novel fluorescence light-up RNA aptamer (FLAP) that transiently binds a fluorogenic rhodamine dye. Fast dye association and dissociation result in intermittent fluorescence emission, facilitating single-molecule localization microscopy (SMLM) with an image resolution not limited by photobleaching. We demonstrate RhoBAST’s excellent properties as a RNA marker by resolving subcellular and subnuclear structures of RNA in live and fixed cells by SMLM and structured illumination microscopy (SIM). 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.03.12.988782; this version posted March 13, 2020.
    [Show full text]
  • Download Author Version (PDF)
    RSC Advances This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. This Accepted Manuscript will be replaced by the edited, formatted and paginated article as soon as this is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/advances Page 1 of 33 RSC Advances A ratiometric nanosensor based on fluorescent carbon dots for label-free and highly selective recognition of DNA Shan Huang a, Lumin Wang a, Fawei Zhu a, Wei Su a, Jiarong Sheng a, Chusheng Huang a, and Qi Xiao a,b,* a College of Chemistry and Materials Science, Guangxi Teachers Education University, Nanning 530001, P. R. China b State Key Laboratory of Virology, Wuhan University, Wuhan 430072, P. R. China Manuscript Accepted Advances * Corresponding author. Tel.: +86 771 3908065; Fax: +86 771 3908065; E-mail address: [email protected] RSC 1 RSC Advances Page 2 of 33 Abstract: A ratiometric nanosensor for label-free and highly selective recognition of DNA was reported in this work, by employing fluorescent carbon dots (CDs) as the reference fluorophore and ethidium bromide (EB), a specific organic fluorescent dye toward DNA, playing the role as both specific recognition element and response signal.
    [Show full text]
  • Process Applications of Phase Fluorometric Oxygen Analyzers
    PROCESS APPLICATIONS OF A PHASE FLUOROMETRIC OXYGEN ANALYZER Phil Harris Melvin Thweatt HariTec Barben Analyzer Technology KEYWORDS Fluorometry, Fluorescence Quenching, Oxygen Sensing, Optical Sensors, Fiber-optics ABSTRACT The operational characteristics, performance and applications of a phase fluorometric oxygen analyzer are presented. The analyzer measures the quenched fluorescence of an oxygen-sensitive ruthenium complex, which is embedded in a porous sol-gel or silicone matrix. The fluorescence lifetime is related to the oxygen concentration via the Stern-Volmer equations. The result is an extremely sensitive and specific fiber-optic oxygen sensor that is applicable to gas phase analysis as well as the measurement of dissolved oxygen in aqueous systems. Applications range from ppm oxygen measurements in hydrocarbon streams to ppb aqueous measurements to percent levels of oxygen in stack gas. INTRODUCTION Oxygen is the most prevalent element in the Earth’s crust, is fundamental to life as we know it, and is one of the prerequisites for chemical combustion. The measurement of oxygen concentration is of value to many industrial process applications, as well as in environmental monitoring of both gases and liquids. This has resulted in oxygen being one of the most commonly measured chemical species, and understandably the measurement of oxygen represents a substantial component of the process analyzer market. Oxygen is often used as a reactant in many chemical processes, and the amount of excess oxygen must often be carefully controlled. In some cases, such as in stack gas incineration, the control is “loose” in that assurance there is excess oxygen available for the incinerator to operate correctly is all that is needed.
    [Show full text]
  • Virus-Based Nanoparticles for Cancer Drug Delivery
    VIRUS-BASED NANOPARTICLES FOR CANCER DRUG DELIVERY By ANNA ELIZABETH CZAPAR Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Dissertation Advisor: Dr. Nicole F. Steinmetz Department of Pathology CASE WESTERN RESERVE UNIVERSITY August 2017 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of Anna Elizabeth Czapar candidate for the Doctor of Philosophy degree*. (signed) George Dubyak, PhD (chair of the committee) Analisa DiFeo, PhD James Anderson, MD, PhD Clive Hamlin, PhD Nicole F. Steinmetz, PhD (date) April 21, 2017 *We also certify that written approval has been obtained for any proprietary material contained therein. i Table of Contents List of Tables…..………………………………………………….………………...…...vi List of Figures…………………………………………………......................................vii Acknowledgements………………………………………………………………............x List of Abbreviations…………………………………………………………………...xii Abstract……………………………………………………………………....................xvi Chapter 1:Introduction………………………………………….....................................1 1.1 Introduction…………………………………………..........................................................1 1.2 Drug delivery………………………………………….......................................................4 1.3 Gene therapy…………………………………………........................................................8 1.4 Immunotherapies and vaccines………………………………………….......................10 1.5 Conclusions…………………………………………........................................................14 1.6 Work cited
    [Show full text]
  • DNA-Binding and Cytotoxicity of Copper(I) Complexes Containing Functionalized Dipyridylphenazine Ligands
    pharmaceutics Article DNA-Binding and Cytotoxicity of Copper(I) Complexes Containing Functionalized Dipyridylphenazine Ligands Sammar Alsaedi 1, Bandar A. Babgi 1,* , Magda H. Abdellattif 2 , Muhammad N. Arshad 3 , Abdul-Hamid M. Emwas 4 , Mariusz Jaremko 5, Mark G. Humphrey 6 , Abdullah M. Asiri 1,3 and Mostafa A. Hussien 1,7 1 Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; [email protected] (S.A.); [email protected] (A.M.A.); [email protected] (M.A.H.) 2 Chemistry Department, Deanship of Scientific Research, College of Sciences, Taif University, Al-Haweiah, P.O. Box 11099, Taif 21944, Saudi Arabia; [email protected] 3 Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia; [email protected] 4 Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia; [email protected] 5 Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; [email protected] 6 Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia; [email protected] Citation: Alsaedi, S.; Babgi, B.A.; 7 Department of Chemistry, Faculty of Science, Port Said University, Port Said 42521, Egypt Abdellattif, M.H.; Arshad, M.N.; * Correspondence: [email protected]; Tel.: +966-555563702 Emwas, A.-H.M.; Jaremko, M.; Humphrey, M.G.; Asiri, A.M.; Abstract: A set of copper(I) coordination compounds with general formula [CuBr(PPh3)(dppz-R)] Hussien, M.A.
    [Show full text]
  • "Microscopy and Image Analysis"
    Microscopy and Image Analysis UNIT 4.4 George McNamara,1 Michael Difilippantonio,2 Thomas Ried,3 and Frederick R. Bieber4 1Biomedical Consultant, Baltimore, Maryland 2Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 3Section of Cancer Genomics, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 4Brigham and Women’s Hospital, Boston, Massachusetts This unit provides an overview of light microscopy, including objectives, light sources, filters, film, and color photography for fluorescence microscopy and fluorescence in situ hybridization (FISH). We believe there are excellent oppor- tunities for cytogeneticists, pathologists, and other biomedical readers, to take advantage of specimen optical clearing techniques and expansion microscopy— we briefly point to these new opportunities. C 2017 by John Wiley & Sons, Inc. Keywords: light microscopy r digital imaging r fluorescence in situ hybridiza- tion r functional genomics How to cite this article: McNamara, G., Difilippantonio, M., Ried, T., & Bieber, F. R. (2017). Microscopy and image analysis. Current Protocols in Human Genetics, 94, 4.4.1–4.4.89. doi: 10.1002/cphg.42 INTRODUCTION by Ishikawa-Ankerhold, Ankerhold, & Drum- This unit provides an overview of light mi- men (2012), and Liu, Ahmed, & Wohland croscopy, including objectives, light sources, (2008). Scanning and transmission electron filters, and imaging for fluorescence mi- microscopy as well as confocal microscopy croscopy and fluorescence in situ hybridiza- and multi-photon excitation microscopy are tion (FISH). We encourage thinking outside not covered in this unit despite their useful- the usual magnification range of 10× to ness as invaluable tools for contemporary stud- 100× objective lenses, by ranging from sin- ies of biological systems; see Diaspro, 2001; gle molecules to whole mice and humans.
    [Show full text]
  • Quenching of the Fluorescence of Tris (2 2-Bipyridine) Ruthenium(II) [Ru(Bipy)3]2+ by a Dimeric Copper(II) Complex
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by East Tennessee State University East Tennessee State University Digital Commons @ East Tennessee State University Electronic Theses and Dissertations Student Works 8-2011 Quenching of the Fluorescence of Tris (2 2-Bipyridine) Ruthenium(II) [Ru(bipy)3]2+ by a Dimeric Copper(II) Complex. Kevin E. Cummins East Tennessee State University Follow this and additional works at: https://dc.etsu.edu/etd Part of the Inorganic Chemistry Commons Recommended Citation Cummins, Kevin E., "Quenching of the Fluorescence of Tris (2 2-Bipyridine) Ruthenium(II) [Ru(bipy)3]2+ by a Dimeric Copper(II) Complex." (2011). Electronic Theses and Dissertations. Paper 1347. https://dc.etsu.edu/etd/1347 This Thesis - Open Access is brought to you for free and open access by the Student Works at Digital Commons @ East Tennessee State University. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Digital Commons @ East Tennessee State University. For more information, please contact [email protected]. Quenching of the Fluorescence of Tris (2,2’-Bipyridine) Ruthenium(II), 2+ [Ru(bipy)3] , by a Dimeric Copper(II) Complex ________________________ A thesis presented to the faculty of the Department of Chemistry East Tennessee State University In partial fulfillment of the requirements for the degree Master of Science in Chemistry ________________________ by Kevin E. Cummins August 2011 _________________________ Jeffrey G. Wardeska, Ph.D., Chair Cassandra Eagle, Ph.D. Ningfeng Zhao, Ph.D. 2+ Keywords: Ruthenium, [Ru(bipy)3] , Dimeric Copper(II), Fluorescence, Quenching ABSTRACT Quenching of the Fluorescence of Tris (2,2’-Bipyridine) Ruthenium(II), 2+ [Ru(bipy)3] , by a Dimeric Copper(II) Complex by Kevin E.
    [Show full text]
  • Photophysical Processes of Ethidium Bromide in Micelles and Reverse Micelles
    J. Phys. Chem. B 1998, 102, 11017-11023 11017 Photophysical Processes of Ethidium Bromide in Micelles and Reverse Micelles Samir Kumar Pal, Debabrata Mandal, and Kankan Bhattacharyya* Physical Chemistry Department, Indian Association for the CultiVation of Science, JadaVpur, Calcutta 700 032, India ReceiVed: May 5, 1998; In Final Form: August 11, 1998 Photophysical processes of ethidium bromide (EB) in homogeneous solutions, micelles, and reverse micelles have been investigated. In acetonitrile, the fluorescence intensity and lifetime of EB are 6.3 ( 0.3 times those in water and 1.25 ( 0.1 times those in acetone. This is attributed to the weaker hydrogen-bond acceptor property of acetonitrile, compared to water and acetone. Addition of water to acetonitrile leads to a marked quenching of the EB emission, with a quenching constant of (1.7 ( 0.3) × 107 M-1 s-1. In aqueous solution, hydroxyl ion quenches EB emission more dramatically with a quenching constant of (4.4 ( 0.4) × 1010 M-1 s-1. This is ascribed to the abstraction of the amino proton of the excited ethidium ion by the hydroxyl ion. Emission properties of EB are found to be good monitors for the micellization of an anionic micelle, sodium dodecyl sulfate (SDS). In AOT microemulsion, EB exhibits nearly (1.8 ( 0.1)-fold emission enhancement relative to water. The emission properties of EB are found to be independent of the water-to-surfactant ratio, w0. In AOT microemulsion when instead of water D2O is injected, a further 2.3 times emission enhancement is observed. However, in AOT microemulsion, the hydroxyl ion does not quench the EB emission, even when a highly alkaline aqueous solution of EB (pH ) 12.6) is injected into the reverse micelle.
    [Show full text]
  • Oxidative Quenching of Photoexcited Ru(II)- Bipyridine Complexes by Oxygen Danielle Rebecca Latham East Tennessee State University
    East Tennessee State University Digital Commons @ East Tennessee State University Undergraduate Honors Theses Student Works 5-2017 Oxidative Quenching of Photoexcited Ru(II)- Bipyridine Complexes by Oxygen Danielle Rebecca Latham East Tennessee State University Follow this and additional works at: https://dc.etsu.edu/honors Part of the Biophysics Commons Recommended Citation Latham, Danielle Rebecca, "Oxidative Quenching of Photoexcited Ru(II)-Bipyridine Complexes by Oxygen" (2017). Undergraduate Honors Theses. Paper 371. https://dc.etsu.edu/honors/371 This Honors Thesis - Open Access is brought to you for free and open access by the Student Works at Digital Commons @ East Tennessee State University. It has been accepted for inclusion in Undergraduate Honors Theses by an authorized administrator of Digital Commons @ East Tennessee State University. For more information, please contact [email protected]. Oxidative Quenching of Photoexcited Ru(II)-Bipyridine Complexes by Oxygen Danielle Latham and Dr. Yuriy Razskazovskiy Department of Physics and Astronomy East Tennessee State University 1. Introduction 1.1 Thermodynamics and Control of Photoinduced Electron Transfer To make a change in a molecule, be it moving an electron, breaking a bond, or combining molecules, some amount of energy is required. In this case, a reduction reaction is in question. A reduction reaction is simply the moving of an electron. This type of reaction leaves the donor (the molecule that donates the electron) with an increased positive charge, and the acceptor (the molecule that accepts the electron) with an increased negative charge. [1] Different electron transfer reactions have standard reduction potentials which is a measure of a species ease of gaining electrons.
    [Show full text]
  • "Microscopy and Image Analysis". In: Current Protocols in Human Genetics
    Microscopy and Image Analysis UNIT 4.4 George McNamara,1 Michael Difilippantonio,2 Thomas Ried,3 and Frederick R. Bieber4 1Biomedical Consultant, Baltimore, Maryland 2Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 3Section of Cancer Genomics, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 4Brigham and Women’s Hospital, Boston, Massachusetts This unit provides an overview of light microscopy, including objectives, light sources, filters, film, and color photography for fluorescence microscopy and fluorescence in situ hybridization (FISH). We believe there are excellent oppor- tunities for cytogeneticists, pathologists, and other biomedical readers, to take advantage of specimen optical clearing techniques and expansion microscopy— we briefly point to these new opportunities. C 2017 by John Wiley & Sons, Inc. Keywords: light microscopy r digital imaging r fluorescence in situ hybridiza- tion r functional genomics How to cite this article: McNamara, G., Difilippantonio, M., Ried, T., & Bieber, F. R. (2017). Microscopy and image analysis. Current Protocols in Human Genetics, 94, 4.4.1–4.4.89. doi: 10.1002/cphg.42 INTRODUCTION by Ishikawa-Ankerhold, Ankerhold, & Drum- This unit provides an overview of light mi- men (2012), and Liu, Ahmed, & Wohland croscopy, including objectives, light sources, (2008). Scanning and transmission electron filters, and imaging for fluorescence mi- microscopy as well as confocal microscopy croscopy and fluorescence in situ hybridiza- and multi-photon excitation microscopy are tion (FISH). We encourage thinking outside not covered in this unit despite their useful- the usual magnification range of 10× to ness as invaluable tools for contemporary stud- 100× objective lenses, by ranging from sin- ies of biological systems; see Diaspro, 2001; gle molecules to whole mice and humans.
    [Show full text]
  • Two-Electron Quenching of Dinuclear Ruthenium(II) Polypyridyl Complexes Yinling Zhang University of Arkansas, Fayetteville
    University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 8-2016 Two-electron Quenching of Dinuclear Ruthenium(II) Polypyridyl Complexes Yinling Zhang University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Biochemistry Commons Recommended Citation Zhang, Yinling, "Two-electron Quenching of Dinuclear Ruthenium(II) Polypyridyl Complexes" (2016). Theses and Dissertations. 1675. http://scholarworks.uark.edu/etd/1675 This Thesis is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. Two-electron Quenching of Dinuclear Ruthenium (II) Polypyridyl Complexes A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Chemistry by Yinling Zhang Jilin University Bachelor of Science in Chemistry, 2010 Jilin University Master of Science in Chemistry, 2013 August 2016 University of Arkansas This thesis is approved for recommendation to the Graduate Council. __________________________ Dr. Bill Durham Thesis Advisor ______________________________ ______________________________ Dr. Jingyi Chen Dr. Stefan Kilyanek Committee Member Committee Member ABSTRACT A bridging ligand 5,5’-Bi- 1,10-phenanthroline, diphen, was prepared using dichlorobis(triphenylphosphine)Ni(II), Ni(PPh3)2Cl2 as catalyst with a yield of 40%. Yellow cubic crystals were able to obtain from the good purity product for single crystal analysis. The torsion angle between the planes of the subunit phenanthrolines is about 66 degrees. 4+ A dinuclear ruthenium (II) polypyridyl complex, (phen)2Ru(diphen)Ru(phen)2 , was synthesized by using polymeric ruthenium carbonyl compound as the entry point, diphen as the bridging ligand and 1,10-phenanthroline, phen, as the terminal legand.
    [Show full text]
  • A Novel Ruthenium(II) Polypyridyl Complex Bearing 1,8-Naphthyridine As a High Selectivity and Sensitivity Fluorescent Chemosensor for Cu2+ and Fe3+ Ions
    molecules Article A Novel Ruthenium(II) Polypyridyl Complex Bearing 1,8-Naphthyridine as a High Selectivity and Sensitivity Fluorescent Chemosensor for Cu2+ and Fe3+ Ions Chixian He 1,2 , Shiwen Yu 2, Shuye Ma 3, Zining Liu 1, Lifeng Yao 2, Feixiang Cheng 1,2,* and Pinhua Liu 2 1 Center for Yunnan-Guizhou Plateau Chemical Functional Materials and Pollution Control, Qujing Normal University, Qujing 655011, China; [email protected] (C.H.); [email protected] (Z.L.) 2 College of Chemistry and Environmental Science, Qujing Normal University, Qujing 655011, China; [email protected] (S.Y.); [email protected] (L.Y.); [email protected] (P.L.) 3 Department of Medicine, Qujing Qilin Vocational and Technical School, Qujing 655000, China; [email protected] * Correspondence: [email protected]; Tel.: +86-0874-099-8658 Academic Editors: Victor Mamane and John S. Fossey Received: 26 September 2019; Accepted: 31 October 2019; Published: 7 November 2019 Abstract: A novel ruthenium(II) polypyridyl complex bearing 1,8-naphthyridine was successfully designed and synthesized. This complex was fully characterized by EI-HRMS, NMR, and elemental analyses. The recognition properties of the complex for various metal ions were investigated. The results suggested that the complex displayed high selectivity and sensitivity for Cu2+ and Fe3+ ions with good anti-interference in the CH3CN/H2O (1:1, v/v) solution. The fluorescent chemosensor showed obvious fluorescence quenching when the Cu2+ and Fe3+ ions were added. The detection limits of Cu2+ and Fe3+ were 39.9 nmol/L and 6.68 nmol/L, respectively. This study suggested that this Ru(II) polypyridyl complex can be used as a high selectivity and sensitivity fluorescent chemosensor for Cu2+ and Fe3+ ions.
    [Show full text]