DOCSLIB.ORG

An Atom-Probe Tomography Primer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Atom-Probe Tomography Primer and quantitative data on the subnanoscale. APT both supplements and complements existing characterization instruments, such as high-resolution electron micro - An Atom-Probe scopy, scanning transmission electron microscopy, nano-secondary ion mass spectrometry, and electron energy loss Tomography spectroscopy. It is a destructive technique, as one is continuously irreversibly remov- ing atoms from a microtip specimen. The present revolutionary state of APT is Primer due to the confluence of several important technological advances over the past few decades: (1) the development of high- David N. Seidman and Krystyna Stiller, speed electronics that permit a researcher to collect large data sets (hundreds of mil- Guest Editors lions of atoms) in relatively short periods of time; (2) high pulse repetition-rate pico- and femtosecond lasers that permit one to Abstract analyze semiconductors, ceramics, biomin- Atom-probe tomography (APT) is in the midst of a dynamic renaissance as a result erals, and organic materials, in addition of the development of well-engineered commercial instruments that are both robust and to metals, without excessive specimen ergonomic and capable of collecting large data sets, hundreds of millions of atoms, in failures; (3) high-gain, 107, low-noise short time periods compared to their predecessor instruments. An APT setup involves multichannel plates (MCPs) that are used a field-ion microscope coupled directly to a special time-of-flight (TOF) mass to determine the time-of-flight (TOF) of spectrometer that permits one to determine the mass-to-charge states of individual individual ions; (4) delay-line detectors field-evaporated ions plus their x-, y-, and z-coordinates in a specimen in direct space that yield the x- and y-positions of individ- with subnanoscale resolution. The three-dimensional (3D) data sets acquired are ual atoms in an atomic plane; (5) the com- analyzed using increasingly sophisticated software programs that utilize high-end bination of a MCP and a delay-line detector workstations, which permit one to handle continuously increasing large data sets. in series to obtain a position-sensitive APT has the unique ability to dissect a lattice, with subnanometer-scale spatial detector, which yields the x-, y-, and z-coor- resolution, using either voltage or laser pulses, on an atom-by-atom and atomic plane- dinates of atoms in a 3D specimen in direct by-plane basis and to reconstruct it in 3D with the chemical identity of each detected space; (6) the implementation of dual- atom identified by TOF mass spectrometry. Employing pico- or femtosecond laser pulses beam focused ion beam (FIB) microscopy using visible (green or blue light) to ultraviolet light makes the analysis of metallic, for the preparation of a wide range of spec- semiconducting, ceramic, and organic materials practical to different degrees of success. imens, extending signi ficant APT to prob- 2 The utilization of dual-beam focused ion-beam microscopy for the preparation of microtip lems that could not previously be studied; specimens from multilayer and surface films, semiconductor devices, and for producing and (7) relatively high-end workstations that make it possible to analyze increas- site-specific specimens greatly extends the capabilities of APT to a wider range of ingly large data sets using sophisticated scientific and engineering problems than could previously be studied for a wide range of data analysis programs. materials: metals, semiconductors, ceramics, biominerals, and organic materials. The articles in this issue of MRS Bulletin are devoted to the applications of APT to specific problems concerning structural metallic and semiconducting materials, Introduction thin films and multilayers, and organic Nothing tends so much to the period,1 because of the availability of and biological materials and is intended to advancement of knowledge as the reliable and well-engineered commercial give the reader a feeling for the current application of a new instrument. The instruments and data analysis software state of this instrument, which is in flux, native intellectual powers of men in that are both robust and ergonomic. In this and embolden him or her to perform an different times are not so much the article, we first describe the basic physical experiment with this marvelous instru- causes of the different success of principles of APT commencing with the ment, which provides quantitative chemi- their labours, as the peculiar nature field ion microscope (FIM), invented by cal information in direct space that cannot of the means and artificial resources E.W. Müller, which provided the first be obtained with other characterization in their possession. (Sir Humphry images of atoms in direct space, 54 years tools at the subnanoscale. Davy, 1778–1829) ago, on the surfaces of crystalline tungsten specimens. After explaining the basic Field Ion Microscopy in Brief This profound observation is pertinent physics of field-ion microscopy, field ion- A FIM is a lensless point-projection to this issue of MRS Bulletin on atom-probe ization, and field evaporation, we discuss microscope that resolves individual atoms tomography (APT) and its many applica- the physical concepts of modern APTs, on the surface of a sharply pointed tip, tions to an ever-widening range of mate- which permit a researcher to reconstruct radius of curvature of <50 nm, which is rial classes that involve important the positions of individual atoms in a spec- maintained at a positive potential (Vdc) scientific and technological problems in imen in three dimensions (3D) with their with respect to ground. Atomic resolution materials science and engineering. APT is chemical identities (mass-to-charge state FIM images are achieved by cooling a coming of age, after a long gestation ratios, m/n), thereby yielding meaningful microtip to between ≈20 to 120 K in an MRS BULLETIN • VOLUME 34 • OCTOBER 2009 • www.mrs.org/bulletin 717 An Atom-Probe Tomography Primer ultrahigh vacuum (UHV) system using a men on an atom-by-atom and atomic {hkl} V(x) closed-cycle liquid helium refrigerator plane-by-plane basis, thereby exploring Metal Vacuum and placing the microtip at Vdc to generate continuously and systematically the bulk electric fields (E) that are between 15 to 65 of a specimen. Figure 1 is a schematic dia- V nm−1.3 High-purity helium or neon gram illustrating the mechanism by which ∑I − nφ gases, or a mixture of He and Ne gases, are the barrier for an atom to “evaporate” as i 0 used to image atoms utilizing the quan- an ion is strongly reduced by the applica- 0 x tum mechanical phenomenon of field ion- tion of an E field. The height of the so- 4–9 V (x) ization. In these high E fields, He or Ne called Schottky hump, Qn(E), is a sensitive a − atoms are field ionized, ≈45 V nm 1 for He function of E that decreases with increas- Λ ≈ −1 and 35 V nm for Ne, above individual ing E: Qn(E) appears in a Boltzmann factor, –ne E surface atoms. This is because the outer- and therefore field evaporation is also x most electron of every imaging gas atom strongly temperature dependent. This quantum mechanically tunnels into the model for field evaporation is called the sharply pointed tip at the site of an atom to ionic model, as it assumes that all the x Qn(E) s V x create an atomic diameter cone of He+ or atoms on the surface of a specimen exist as i( ) + Ne ions emanating from individual sur- ions. In Figure 1, Va(x) is the potential face atoms. The field-ionized He+ or Ne+ energy of an atom in the absence of an ions are repelled from the positively electric field, and V (x) is the potential Figure 1. V(x) is potential energy as a i function of distance away from the charged ions on the surface of a microtip energy of an ion in its ith ionization state surface of a specimen, x = 0. Va(x) is (specimen) and then accelerated along the in the presence of an electric field; they the potential energy of an atom in the E field lines, which are orthogonal to the differ from one another because of a small absence of an electric field, E, and Vi(x) equipotentials, to a MCP. The energetic difference in the polarizabilities of atoms is the potential energy of an ion in its He+ or Ne+ ions are converted into visible and ions, which is E dependent. i th ionization state in the presence of E. light employing a high-gain MCP. Thus, Ii is the i th ionization state of an ion, e the physical basis of “seeing” atoms in A Primer of Atom-Probe is the charge on an electron, n is the direct space is the quantum-mechanical Tomography number of electronic charges, Λ is the cohesive energy of a solid, φ is the process of field ionization of gas atoms A truly revolutionary advance in instru- 0 local work function, Q (E) is the height associated with the high E fields at indi- mentation occurred when Müller, Panitz, n of the so-called Schottky hump, and xs vidual ions on the surface of a microtip. and McLane invented the atom-probe is the position of the maximum value of + + The field ionized He or Ne ions are the field ion microscope (APFIM) in 1968,14 the Schottky hump. information carrying messengers that per- which consisted of a FIM plus a special mit observation of individual atoms with TOF mass spectrometer, with the ability to subnanometer scale spatial resolution. The detect single pulsed-field-evaporated ions magnification of a FIM image, which is using a high-gain MCP. An APFIM uti- spatial resolution is 0.2 to 0.5 nm within an easily >2 × 106 times, is proportional to the lizes controlled pulsed field evaporation, atomic {hkl} plane, where the exact value tip-to-MCP distance divided by the aver- using either voltage or laser pulses, to depends on {hkl}.
Load more

Recommended publications
  • The Chiton Radula: a Unique Model for Biomineralization Studies
    4 The Chiton Radula: A Unique Model for Biomineralization Studies Lesley R. Brooker1 and Jeremy A. Shaw2 1University of the Sunshine Coast 2Centre for Microscopy, Characterisation & Analysis University of Western Australia Australia 1. Introduction Over the course of evolution, a range of strategies have been developed by different organisms to produce unique materials and structures perfected for their specific function. This biological mastery of materials production has inspired the birth of the new discipline of biomaterials through biomimicry (Birchall, 1989). Chitons (Mollusca: Polyplacophora) are slow moving, bilaterally symmetrical and dorso- ventrally flattened molluscs that are commonly found on hard substrata in intertidal regions of coastlines around the world (Kaas & Jones, 1998). All species are characterized by a series of eight dorsal, articulating shell plates or valves, which may be embedded, to varying degrees, in a fleshy, muscular girdle (Kaas & Jones, 1998) (Figure 1). Approximately 750 living species are known, and while intertidal regions are home to the majority of chitons, a number of species can be found at depths of up to 8000m where they feed on detrital material (Kaas & Jones, 1998). Fig. 1. Photograph of the dorsal surface of the chiton Acanthopleura gaimardi, showing the eight overlapping aragonite plates surrounded by the fleshy girdle, which, in this species, is covered in small aragonite spines. Chitons feed by rasping macro- and micro-algae from the rocks on which they live through the use of a radula. The radula has been coined as a conveyor belt of continuously developing www.intechopen.com 66 Advanced Topics in Biomineralization teeth, replaced by new teeth as they are worn and lost.
    [Show full text]
  • Interfaces and Defect Composition at the Near-Atomic Scale Through Atom Probe Tomography Investigations Baptiste Gault, Andrew J
    Interfaces and defect composition at the near-atomic scale through atom probe tomography investigations Baptiste Gault, Andrew J. Breen, Yanhong Chang, Junyang He, Eric A. Jägle, Paraskevas Kontis, Philipp Kürnsteiner, Alisson Kwiatkowski da Silva, Surendra Kumar Makineni, Isabelle Mouton, Zirong Peng, Dirk Ponge, Torsten Schwarz, Leigh T. Stephenson, Agnieszka Szczepaniak, Huan Zhao, Dierk Raabe Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237, Düsseldorf, Germany. Abstract Atom probe tomography (APT) is rising in influence across many parts of materials science and engineering thanks to its unique combination of highly sensitive composition measurement and three-dimensional microstructural characterization. In this article, we have selected a few recent applications that showcase the unique capacity of APT to measure the local composition at structural defects. Whether we consider dislocations, stacking faults or grain boundary, the detailed compositional measurements tend to indicate specific partitioning behaviors for the different solutes in both complex engineering and model alloys we investigated. Introduction Field-ion-based techniques were initially developed for studying surfaces 1,2: The field ion microscope (FIM) reveals the structure of a material with atomic-scale resolution 3, at least in some parts of the image, while the implementation of a time-of-flight spectrometer onto a field ion microscope, which is the atom probe, targeted the elemental identification of atoms images at the surface 4. The level of detail of the intimate structure of crystalline defects, being grain boundaries 5 or dislocations 6, brought by FIM was astonishing, and the technique is unrivalled when it comes to observing individual vacancies 7,8.
    [Show full text]
  • SOFFA, William Anthony, 1939- a FIELD-ION MICROSCOPY STUDY of SOME TUNGSTEN-RHENIUM and MOLYBDENUM- RHENIUM ALLOYS
    This dissertation has been microfilmed exactly as received 67-10,926 SOFFA, William Anthony, 1939- A FIELD-ION MICROSCOPY STUDY OF SOME TUNGSTEN-RHENIUM AND MOLYBDENUM- RHENIUM ALLOYS. The Ohio State University, Ph.D., 1967 Engineering, metallurgy University Microfilms, Inc., Ann Arbor, Michigan All Rights Reserved A FIELD-ION MICROSCOPY STUDY OF SOME TUNGSTEN-RHENIUM AND MOLYBDENUM-RHENIUM ALLOYS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Decree Doctor of Philosophy in the Graduate School of The Ohio State University By William Anthony Soffa, 13.S. , M.S. * # # # The Ohio State University 1967 Approved by / ..Adviser/] Department of Metallurgical Engineering To my Wife and Daughter ACKNOWLEDGMENTS The author is grateful for the continued encouragement and guidance of Professor K. L. Moazed during the course of this work. The author also gratefully acknowledges the many faceted contribution and inspiration of Professor J. P. Hirth throughout his undergraduate and graduate studies. ii VITA June 1, 1939 Born - Pittsburgh, Pennsylvania 1961 .... B.S., Carnegie Institute of Technology, Pittsburgh, Pennsylvania 1961-1963 . Graduate Assistant, Department of Materials Engineering, Rensselaer Polytechnic Institute, Troy, New York 1963 . M.S., Rensselaer Polytechnic Institute, Troy, New York 1963-1967 . Research Fellow, The Department of Metallurgical Engineering, The Ohio State University, Columbus, Ohio FIELDS OF STUDY Major Field: Physical Metallurgy Studies in Physical Metallurgy. Professors K. L. Moazed, Gordon W. Powell and J. W. Spretnak Studies in Mechanical Metallurgy. Professor J. W. Spretnak Studies in Dislocation Theory. Professor J. P. Hirth Studies in Thermodynamics and Kinetics. Professors R. A. Rapp and R. Speiser Studies in Corrosion and Oxidation.
    [Show full text]
  • Helium Ion Microscopy
    Helium Ion Microscopy Gregor Hlawacek,1, a) Vasilisa Veligura,1 Raoul van Gastel,1 and Bene Poelsema1 Physics of Interfaces and Nanomaterials, MESA+ Research Institute, University of Twente, PO Box 217, 7500AE Enschede, The Netherlands (Dated: Tuesday 14th January, 2014) Helium Ion Microcopy (HIM) based on Gas Field Ion Sources (GFIS) represents a new ultra high resolution microscopy and nano–fabrication technique. It is an enabling technology that not only provides imagery of conducting as well as uncoated insulating nano–structures but also allows to create these features. The latter can be achieved using resists or material removal due to sputtering. The close to free–form sculpting of structures over several length scales has been made possible by the extension of the method to other gases such as Neon. A brief introduction of the underlying physics as well as a broad review of the applicability of the method is presented in this review. I. INTRODUCTION High resolution imaging, in particular in biology and materials science, is mostly done using Scanning Electron Microscopy (SEM). The ease of use and the widespread availability has made this the number one method for imaging in the aforementioned fields. Structuring and manipulation of nano–sized features is traditionally the domain of Focused Ion Beams. Here, mainly liquid metal ion sources (LMIS) using Gallium are used. However, 1 other techniques such as various types of GFIS, alloy Figure 1. (Color online) (a) Sketch of a GFIS. Ionization LMIS,2 magneto optical trap sources (MOTIS)3 and mul- 4 happens dominantly at the most protruding corner and edge ticusp plasma sources are runners–up.
    [Show full text]
  • Three-Dimensional Nanoscale Characterisation of Materials by Atom Probe Tomography
    International Materials Reviews ISSN: 0950-6608 (Print) 1743-2804 (Online) Journal homepage: http://www.tandfonline.com/loi/yimr20 Three-dimensional nanoscale characterisation of materials by atom probe tomography Arun Devaraj, Daniel E. Perea, Jia Liu, Lyle M. Gordon, Ty. J. Prosa, Pritesh Parikh, David R. Diercks, Subhashish Meher, R. Prakash Kolli, Ying Shirley Meng & Suntharampillai Thevuthasan To cite this article: Arun Devaraj, Daniel E. Perea, Jia Liu, Lyle M. Gordon, Ty. J. Prosa, Pritesh Parikh, David R. Diercks, Subhashish Meher, R. Prakash Kolli, Ying Shirley Meng & Suntharampillai Thevuthasan (2017): Three-dimensional nanoscale characterisation of materials by atom probe tomography, International Materials Reviews, DOI: 10.1080/09506608.2016.1270728 To link to this article: http://dx.doi.org/10.1080/09506608.2016.1270728 Published online: 26 Jan 2017. Submit your article to this journal Article views: 11 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=yimr20 Download by: [The UC San Diego Library] Date: 30 January 2017, At: 14:49 INTERNATIONAL MATERIALS REVIEWS, 2017 http://dx.doi.org/10.1080/09506608.2016.1270728 FULL CRITICAL REVIEW Three-dimensional nanoscale characterisation of materials by atom probe tomography Arun Devaraja, Daniel E. Pereab, Jia Liub, Lyle M. Gordonb, Ty. J. Prosac, Pritesh Parikhd, David R. Diercks e, Subhashish Meherf, R. Prakash Kolli g, Ying Shirley Mengd and Suntharampillai Thevuthasanh
    [Show full text]
  • Helium Ion Microscopy (HIM) for The
    OPEN Helium Ion Microscopy (HIM) for the SUBJECT AREAS: imaging of biological samples at IMAGING TECHNIQUES AND sub-nanometer resolution INSTRUMENTATION Matthew S. Joens1, Chuong Huynh2, James M. Kasuboski1, David Ferranti2, Yury J. Sigal1, Fabian Zeitvogel3, Martin Obst3, Claus J. Burkhardt4, Kevin P. Curran5, Sreekanth H. Chalasani5, Received Lewis A. Stern2, Bernhard Goetze2 & James A. J. Fitzpatrick1 2 October 2013 Accepted 1Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, 26 November 2013 USA, 2Ion Microscopy Innovation Center, Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA, 3Center 4 Published for Applied Geosciences, University Tu¨bingen, Hoelderlinstr. 12, 72074 Tuebingen, Germany, NMI Natural and Medical 5 17 December 2013 Sciences Institute, Markwiesenstr. 55, 72770 Reutlingen, Germany, Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA. Correspondence and Scanning Electron Microscopy (SEM) has long been the standard in imaging the sub-micrometer surface requests for materials ultrastructure of both hard and soft materials. In the case of biological samples, it has provided great insights should be addressed to into their physical architecture. However, three of the fundamental challenges in the SEM imaging of soft materials are that of limited imaging resolution at high magnification, charging caused by the insulating J.A.J.F. (fitzp@salk. properties of most biological samples and the loss of subtle surface features by heavy metal coating. These edu) challenges have recently been overcome with the development of the Helium Ion Microscope (HIM), which boasts advances in charge reduction, minimized sample damage, high surface contrast without the need for metal coating, increased depth of field, and 5 angstrom imaging resolution.
    [Show full text]
  • Materials Science and Engineering
    Materials Science and Engineering Robert R. McCormick School of Engineering and Applied Science Northwestern University SPRING 2011 Two MSE Professors Chad Mirkin Now Elected Elected to American Academy to All Three Branches of the of Arts and Sciences National Academies orthwestern University scientist Chad A. Mirkin, a world- renowned leader in nanotechnology research and its application, Nhas been elected a member of the prestigious Institute of Medicine (IOM). He is the first at Northwestern and in the Midwest and the 10th in the world to be elected to all three branches of the National Academies. Mirkin was elected a member of the National Academy of Sciences earlier this year and a member of the National Academy of Engineering in 2009. Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg New AAAS inductees David Seidman and Monica Olvera de la Cruz. College of Arts and Sciences and profes- wo McCormick materials science and engineering professors — sor of medicine, chemical and biological Monica Olvera de la Cruz and David Seidman — were elected to engineering, biomedical engineering and T the prestigious American Academy of Arts and Sciences, one of the materials science and engineering and nation’s oldest honorary societies and independent policy research centers. director of Northwestern’s International Olvera de la Cruz is the Lawyer Taylor Professor of Material Science Institute for Nanotechnology. and Engineering, chemical and biological engineering, and chemistry. Membership in the IOM is one of the highest honors in the fields of Seidman is Walter P. Murphy Professor of Materials Science and Engineer- Chad Mirkin ing.
    [Show full text]
  • Atom Probe Tomography Analysis of Exsolved Mineral Phases
    Journal of Visualized Experiments www.jove.com Video Article Atom Probe Tomography Analysis of Exsolved Mineral Phases Kimberly Genareau1, Alberto Perez-Huerta1, Fernando Laiginhas1 1 Department of Geological Sciences, University of Alabama Correspondence to: Kimberly Genareau at [email protected], Alberto Perez-Huerta at [email protected] URL: https://www.jove.com/video/59863 DOI: doi:10.3791/59863 Keywords: Environmental Sciences, Issue 152, Atom probe tomography, APT, volcanic ash, titanomagnetite, ilmenite, exsolution lamellae, FIB-SEM lift-out, LEAP Date Published: 10/25/2019 Citation: Genareau, K., Perez-Huerta, A., Laiginhas, F. Atom Probe Tomography Analysis of Exsolved Mineral Phases. J. Vis. Exp. (152), e59863, doi:10.3791/59863 (2019). Abstract Element diffusion rates and temperature/pressure control a range of fundamental volcanic and metamorphic processes. Such processes are often recorded in lamellae exsolved from host mineral phases. Thus, the analysis of the orientation, size, morphology, composition and spacing of exsolution lamellae is an area of active research in the geosciences. The conventional study of these lamellae has been conducted by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and more recently with focused ion beam (FIB)-based nanotomography, yet with limited chemical information. Here, we explore the use of atom probe tomography (APT) for the nanoscale analysis of ilmenite exsolution lamellae in igneous titanomagnetite from ash deposits erupted from the active Soufrière Hills Volcano (Montserrat, British West Indies). APT allows the precise calculation of interlamellar spacings (14–29 ± 2 nm) and reveals smooth diffusion profiles with no sharp phase boundaries during the exchange of Fe and Ti/O between the exsolved lamellae and the host crystal.
    [Show full text]
  • J. A. Panitz Is Emeritus Professor of Physics at the University of New Mexico (UNM)
    CURRICULUM VITAE John Andrew Panitz J. A. Panitz is Emeritus Professor of Physics at the University of New Mexico (UNM). He joined UNM in 1988 and during his tenure he was Professor of Physics, Professor of High Technology Materials and Professor of Cell Biology in the School of Medicine. At UNM he developed Visual E&M the first undergraduate laboratory courseware that encouraged critical thinking and role playing in the structured environment of cooperative learning groups. From 1970 to 1988 Professor Panitz was a member of the technical staff at Sandia National Laboratory in Albuquerque. At Sandia he invented and patented the LiFE detector an immunochemical sensor, the 10 cm Atom Probe and the Field Desorption Spectrometer that became the Imaging Atom Probe - the progenitor of commercial atom probes and Atom Probe Tomography. Visit the Atom Probe Museum In 1993 Professor Panitz founded High-Field Consultants to provide expertise and training in high-field phenomena and chemical analysis at the atomic level. Research Interests Molecular imaging in high electric fields. Binding of biological molecules at metal and semiconductor surfaces from aqueous solution using cryopreparation and cryofixation techniques. Field Ion Microscopy, Atom-Probe Tomography, field-ionization, field electron emission tunneling and field ionization of liquid metals. Education and Professional Experience 2004 Emeritus Professor of Physics. Department of Physics and Astronomy. The University of New Mexico. Albuquerque, NM 87131. 2001 - 2004 Professor of Physics. Department of Physics and Astronomy. Professor of High-Technology Materials, Center for HTC. Professor of Cell Biology and Physiology, School of Medicine. The University of New Mexico. Albuquerque, NM 87131.
    [Show full text]
  • Implementation of Atomically Defined Field Ion Microscopy Tips in Scanning Probe Microscopy
    Implementation of atomically defined Field Ion Microscopy tips in Scanning Probe Microscopy William Paul, Yoichi Miyahara, and Peter Grütter Department of Physics, Faculty of Science, McGill University, Montreal, Canada. E-mail: [email protected] Abstract The Field Ion Microscope (FIM) can be used to characterize the atomic configuration of the apex of sharp tips. These tips are well suited for Scanning Probe Microscopy (SPM) since they predetermine SPM resolution and electronic structure for spectroscopy. A protocol is proposed to preserve the atomic structure of the tip apex from etching due to gas impurities during the transfer period from FIM to SPM, and estimations are made regarding the time limitations of such an experiment due to contamination by ultra-high vacuum (UHV) rest gases. While avoiding any current setpoint overshoot to preserve the tip integrity, we present results from approaches of atomically defined tungsten tips to the tunneling regime with Au(111), HOPG, and Si(111) surfaces at room temperature. We conclude from these experiments that adatom mobility and physisorbed gas on the sample surface limit the choice of surfaces for which the tip integrity is preserved in tunneling experiments at room temperature. The atomic structure of FIM tip apices is unchanged only after tunneling to the highly reactive Si(111) surface. 1. Introduction experiments[7–11]. These, and other combined FIM/STM studies [12–15] shed light on some of the atom transfer The utility of the Field Ion Microscope (FIM) for processes in the tip-sample junction. A detailed study characterizing tips destined for Scanning Tunneling presenting a protocol for the preservation of tip apex structures Microscopy (STM) experiments was first considered by Fink in SPM experiments still does not exist.
    [Show full text]
  • Prelimary Studies by Field Ion Microscopy of Adhesion Pf Platinum
    https://ntrs.nasa.gov/search.jsp?R=19710028565 2020-03-23T15:56:44+00:00Z PRELIMINARY STUDIES BY FIELD ION MICROSCOPY OF ADHESION OF PLATINUM AND GOLD ' TO TUNGSTEN AND IRIDIUM 4 I by K7illium A. Bruinurd und Donuld H. Bnckley Lewis Reseurch Center I NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. OCTOBER 1971 i TECH LIBRARY KAFB, NM - 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. NASA TN D-6492 I 4. Title and Subtitle PRELIMINARY STUDIES BY FIELD ION MICROS- 5. Report Date COPY OF ADHESION OF PLATINUM AND GOLD TO October-- 1971 TUNGSTEN AND IRIDIUM 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. William A. Brainard and Donald H. Buckley E-6383 ~~ 10. Work Unit No. 9. Performing Organization Name and Address 129-03 Lewis Research Center 11. Contract or Grant No. National Aeronautics and Space Administration Cleveland, Ohio 44135 13. Type of Report and Period Covered 2. Sponsoring Agency Name and Address Technical Note ~~ National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, D. C. 20546 5. Supplementary Notes 6. Abstract Adhesion experiments with platinum and gold contacting tungsten and iridium field-ion- microscope emitter tips were conducted in vacuum. Platinum contacting tungsten at 300 K showed an ordered surface believed to represent mechanical transfer of the platinum onto the tungsten in an ordered manner. Gold contacting tungsten at 78 K showed essentially a random transfer with some clustering of gold atoms. Gold transferred onto iridium by contacting at 78 K presented an ordered appearance due to decoration of ledge sites by the gold atoms.
    [Show full text]
  • The Microscope; However, It Is Not the First Time Collector’S Item
    69 VOLUME 54, THIRD/FOURTH QUARTER, 2006 CONTENTS VOL. 54 NO. 3/4 Editorial ii Gary J. Laughlin Note on Page Numbering in Volume 15 iv Cumulative Indexes 1937 - 2006 (Volumes 1 - 54) Author Index 5 Subject Index 87 Book Reviews (by Author) 188 EDITORIAL This issue is the complete 69 year index of the con- light microscope was in danger of becoming a tents of The Microscope; however, it is not the first time collector’s item. In fact, for years I believed that this that a cumulative index for this journal has been made was a modern dilemma but it wasn’t until Dr. McCrone available for its readers. An earlier version was pub- told me that when he left Cornell, he was unable to lished as a supplement in 1982 (covering Volumes 1- find anyone in industry who really knew what the 30) and again, after the completion of the first 50 years light microscope or a chemical microscopist could do. of The Microscope, in 1987 (Vol. 35:4). Because these two Armour Research Foundation in Chicago took a chance early indexes are no longer available and nearly 20 and hired him — that was 1948. The rest is history. additional years have passed, we thought it a good The light microscope has been accused of being idea to bring things up to date and make the complete too simple or too complicated, too subjective, or too author, subject, and book review indexes available as unreliable — as compared to automated alternatives. a single-volume print issue that will now, for the first Microscopists couldn’t disagree more: the results pro- time, also be available in electronic format.
    [Show full text]