Michael A. O'Keefe

Last updated

Michael A. O'Keefe (born 8 September 1942, in East Melbourne, Australia) is a physicist who has worked in materials science and electron microscopy. [1] He is perhaps best known for his production of the seminal computer code for modeling of high-resolution transmission electron microscopy (HRTEM) images; [2] his software was later made available [3] as part of the DeepView package [4] for remote electron microscopy [5] and control. [6] [7] O'Keefe's tutorial on theory and application of high-resolution electron microscope image simulation is available online. [8]

O'Keefe has established methods of quantifying resolution quality, and methods of deriving accurate atom positions from high-resolution images. [9] He used these methods to help establish high-resolution electron microscopy as a precise science; in addition to its more-pedestrian role of pictorial confirmation of nano measurements, he demonstrated HRTEM's value in measurement of nano-properties. [10] The video [11] and associated slides [12] illustrate the role of his work in providing tools for nano-characterization.

O'Keefe designed and developed the one-Ångström microscope (OÅM) for the National Center for Electron Microscopy at Lawrence Berkeley National Laboratory based on an FEI Company CM300 microscope that he modified extensively to improve coherence and correct three-fold astigmatism. He was successful in breaking the "one-Ångström barrier" to resolution using his combination of hardware and software correction of microscope aberrations. He produced the first HRTEM images to show carbon atoms separated by less than one Ångström in diamond (0.89 Å) [13] and silicon atoms in crystalline silicon (0.78 Å) [14] —an example of his silicon work appears on a webpage at the Department of Energy. [15] His OÅM was the first HRTEM able to image the smallest metal atoms (lithium) in lithium battery materials. [16] Building on his work designing and operating his one-Ångström microscope (OÅM), O'Keefe produced the design for the LBNL TEAM (transmission electron aspheric microscope) able to resolve atoms in the deep sub-Ångström resolution region (less than 0.5 Å) using a hardware electron-wave phase-corrector (Cs corrector) in combination with a coherence-enhancing electron-beam monochromator. [17]

Related Research Articles

<span class="mw-page-title-main">Electron microscope</span> Type of microscope with electrons as a source of illumination

An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes. Electron microscope may refer to:

<span class="mw-page-title-main">Microscope</span> Scientific instrument

A microscope is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope.

<span class="mw-page-title-main">Cathodoluminescence</span> Photon emission under the impact of an electron beam

Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is the generation of light by an electron beam scanning the phosphor-coated inner surface of the screen of a television that uses a cathode ray tube. Cathodoluminescence is the inverse of the photoelectric effect, in which electron emission is induced by irradiation with photons.

<span class="mw-page-title-main">Electron energy loss spectroscopy</span> Form of microscopy using an electron beam

Electron energy loss spectroscopy (EELS) is a form of electron microscopy in which a material is exposed to a beam of electrons with a known, narrow range of kinetic energies. Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected. The amount of energy loss can be measured via an electron spectrometer and interpreted in terms of what caused the energy loss. Inelastic interactions include phonon excitations, inter- and intra-band transitions, plasmon excitations, inner shell ionizations, and Cherenkov radiation. The inner-shell ionizations are particularly useful for detecting the elemental components of a material. For example, one might find that a larger-than-expected number of electrons comes through the material with 285 eV less energy than they had when they entered the material. This is approximately the amount of energy needed to remove an inner-shell electron from a carbon atom, which can be taken as evidence that there is a significant amount of carbon present in the sample. With some care, and looking at a wide range of energy losses, one can determine the types of atoms, and the numbers of atoms of each type, being struck by the beam. The scattering angle can also be measured, giving information about the dispersion relation of whatever material excitation caused the inelastic scattering.

<span class="mw-page-title-main">Transmission electron microscopy</span> Imaging and diffraction using electrons that pass through samples

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a detector such as a scintillator attached to a charge-coupled device or a direct electron detector.

Scanning probe microscopy (SPM) is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. SPM was founded in 1981, with the invention of the scanning tunneling microscope, an instrument for imaging surfaces at the atomic level. The first successful scanning tunneling microscope experiment was done by Gerd Binnig and Heinrich Rohrer. The key to their success was using a feedback loop to regulate gap distance between the sample and the probe.

<span class="mw-page-title-main">X-ray microscope</span> Type of microscope that uses X-rays

An X-ray microscope uses electromagnetic radiation in the X-ray band to produce magnified images of objects. Since X-rays penetrate most objects, there is no need to specially prepare them for X-ray microscopy observations.

<span class="mw-page-title-main">Transmission Electron Aberration-Corrected Microscope</span>

Transmission Electron Aberration-Corrected Microscope (TEAM) is a collaborative research project between four US laboratories and two companies. The project's main activity is design and application of a transmission electron microscope (TEM) with a spatial resolution below 0.05 nanometers, which is roughly half the size of an atom of hydrogen.

Electron crystallography is a subset of methods in electron diffraction focusing just upon detailed determination of the positions of atoms in solids using a transmission electron microscope (TEM). It can involve the use of high-resolution transmission electron microscopy images, electron diffraction patterns including convergent-beam electron diffraction or combinations of these. It has been successful in determining some bulk structures, and also surface structures. Two related methods are low-energy electron diffraction which has solved the structure of many surfaces, and reflection high-energy electron diffraction which is used to monitor surfaces often during growth.

<span class="mw-page-title-main">Scanning transmission electron microscopy</span> Scanning microscopy using thin samples and transmitted electrons

A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike CTEM, in STEM the electron beam is focused to a fine spot which is then scanned over the sample in a raster illumination system constructed so that the sample is illuminated at each point with the beam parallel to the optical axis. The rastering of the beam across the sample makes STEM suitable for analytical techniques such as Z-contrast annular dark-field imaging, and spectroscopic mapping by energy dispersive X-ray (EDX) spectroscopy, or electron energy loss spectroscopy (EELS). These signals can be obtained simultaneously, allowing direct correlation of images and spectroscopic data.

<span class="mw-page-title-main">Department of Materials, University of Oxford</span>

The Department of Materials at the University of Oxford, England was founded in the 1950s as the Department of Metallurgy, by William Hume-Rothery, who was a reader in Oxford's Department of Inorganic Chemistry. It is part of the university's Mathematical, Physical and Life Sciences Division

Phase-contrast imaging is a method of imaging that has a range of different applications. It measures differences in the refractive index of different materials to differentiate between structures under analysis. In conventional light microscopy, phase contrast can be employed to distinguish between structures of similar transparency, and to examine crystals on the basis of their double refraction. This has uses in biological, medical and geological science. In X-ray tomography, the same physical principles can be used to increase image contrast by highlighting small details of differing refractive index within structures that are otherwise uniform. In transmission electron microscopy (TEM), phase contrast enables very high resolution (HR) imaging, making it possible to distinguish features a few Angstrom apart.

<span class="mw-page-title-main">Focused ion beam</span> Device

Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor industry, materials science and increasingly in the biological field for site-specific analysis, deposition, and ablation of materials. A FIB setup is a scientific instrument that resembles a scanning electron microscope (SEM). However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB setup uses a focused beam of ions instead. FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams. FIB should not be confused with using a beam of focused ions for direct write lithography. These are generally quite different systems where the material is modified by other mechanisms.

<span class="mw-page-title-main">High-resolution transmission electron microscopy</span>

High-resolution transmission electron microscopy is an imaging mode of specialized transmission electron microscopes that allows for direct imaging of the atomic structure of samples. It is a powerful tool to study properties of materials on the atomic scale, such as semiconductors, metals, nanoparticles and sp2-bonded carbon. While this term is often also used to refer to high resolution scanning transmission electron microscopy, mostly in high angle annular dark field mode, this article describes mainly the imaging of an object by recording the two-dimensional spatial wave amplitude distribution in the image plane, similar to a "classic" light microscope. For disambiguation, the technique is also often referred to as phase contrast transmission electron microscopy, although this term is less appropriate. At present, the highest point resolution realised in high resolution transmission electron microscopy is around 0.5 ångströms (0.050 nm). At these small scales, individual atoms of a crystal and defects can be resolved. For 3-dimensional crystals, it is necessary to combine several views, taken from different angles, into a 3D map. This technique is called electron tomography.

An X-ray microscope uses electromagnetic radiation in the soft X-ray band to produce images of very small objects.

The Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) is an institute located on the campus of Forschungszentrum Jülich belonging to the Helmholtz Association of German Research Centres. It comprises three divisions: ER-C-1 “Physics of Nanoscale systems”, ER-C-2 “Materials Science and Technology” and ER-C-3 “Structural Biology”.

<span class="mw-page-title-main">Crystallographic image processing</span>

Crystallographic image processing (CIP) is traditionally understood as being a set of key steps in the determination of the atomic structure of crystalline matter from high-resolution electron microscopy (HREM) images obtained in a transmission electron microscope (TEM) that is run in the parallel illumination mode. The term was created in the research group of Sven Hovmöller at Stockholm University during the early 1980s and became rapidly a label for the "3D crystal structure from 2D transmission/projection images" approach. Since the late 1990s, analogous and complementary image processing techniques that are directed towards the achieving of goals with are either complementary or entirely beyond the scope of the original inception of CIP have been developed independently by members of the computational symmetry/geometry, scanning transmission electron microscopy, scanning probe microscopy communities, and applied crystallography communities.

<span class="mw-page-title-main">Ondrej Krivanek</span> British physicist

Ondrej L. Krivanek is a Czech/British physicist resident in the United States, and a leading developer of electron-optical instrumentation. He won the Kavli Prize for Nanoscience in 2020 for his substantial innovations in atomic resolution electron microscopy.

Quantum microscopy allows microscopic properties of matter and quantum particles to be measured and imaged. Various types of microscopy use quantum principles. The first microscope to do so was the scanning tunneling microscope, which paved the way for development of the photoionization microscope and the quantum entanglement microscope.

Peter David Nellist, is a British physicist and materials scientist, currently a professor in the Department of Materials at the University of Oxford. He is noted for pioneering new techniques in high-resolution electron microscopy.

References

  1. ↑ "Profile". Archived from the original on 1 July 2007. Retrieved 25 March 2009.
  2. ↑ O'Keefe, M. A.; Buseck, P. R.; Iijima, S. (1978). "Computed crystal structure images for high resolution electron microscopy" (PDF). Nature. 274 (5669): 322–324. Bibcode:1978Natur.274..322O. doi:10.1038/274322a0. S2CID   4163994.
  3. ↑ "OLIS: On-Line Image Simulation and structure characterization for the Materials Microcharacterization Collaboratory".
  4. ↑ Parvin, B.; Taylor, J.; Cong, G.; Okeefe, M. A.; Barcellos-Hoff, M. H. (1999). "Deep View". Proceedings of the 1999 ACM/IEEE conference on Supercomputing (CDROM) - Supercomputing '99. pp. 65–es. doi:10.1145/331532.331597. ISBN   1581130910. S2CID   6469606.
  5. ↑ "Berkeley Lab Currents -- June 12, 1998".
  6. ↑ Preuss, Paul. "Look Deep, Look Far: Remote Microscopy and Telescopy". Archived from the original on 13 April 2021.
  7. ↑ O'Keefe, M.; Parvin, B.; Owen, D.; Taylor, J.; Westmacott, K.; Johnston, W.; Dahmen, U. "Automation for on-line remote-control in-situ electron microscopy". escholarship.org. Lawrence Berkeley National Laboratory. Retrieved 1 June 2024.
  8. ↑ O'Keefe, M. A. (August 1994). "Interpretation of HRTEM images by image simulation: An introduction to theory and practice".
  9. ↑ "HRTEM imaging of atoms at sub-Ångström resolution". Archived from the original on 13 July 2012. Retrieved 8 July 2010.
  10. ↑ O'Keefe, Michael A.; Allard, Lawrence F. (18 January 2004). "Sub-Angstrom electron microscopy for sub-Angstrom nano-metrology".
  11. ↑ Workshop. Archived from the original on 13 November 2008. Retrieved 26 March 2009.
  12. ↑ "Data Management workshop - Nanosciences". 16 March 2004. Archived from the original (PPT) on 29 June 2013.
  13. ↑ "BBC News | Sci/Tech | Scientists see atoms in diamond".
  14. ↑ "Berkeley Lab Currents -- May 18, 2001".
  15. ↑ "The Scale of Things". Archived from the original on 1 February 2010. Retrieved 31 January 2010.
  16. ↑ Shao-Horn, Yang; Croguennec, Laurence; Delmas, Claude; Nelson, E. Chris; O'Keefe, Michael A. (2003). "Atomic resolution of lithium ions in LiCoO2". Nature Materials. 2 (7): 464–467. Bibcode:2003NatMa...2..464S. doi:10.1038/nmat922. PMID   12806387. S2CID   34357573.
  17. ↑ "HRTEM at half-Angstrom resolution: From OAM to TEAM". 2003. Retrieved 1 June 2024.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.