The TEAM0.5 microscope: Single atom detection across the Periodic Table of Element
Seminar by Christian Kisielowski, National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, USA.
Abastract
The Transmission Electron Aberration-corrected Microscope (TEAM)
project was initiated as a collaborative effort to redesign the
electron microscope around aberration corrected optics [1]. The Project
aims at extending the spatial resolution to 50 pm and at improving
contrast, stability, sensitivity, brightness and energy resolution. A
prototype (TEAM0.5) of such an instrument became recently available
[2]. One outstanding goal of the ongoing efforts in electron microscopy
is the realization of electron tomography with atomic resolution. In
this context it is of essence characterizing achievable signal-to-noise
ratios for the detection of single atoms and controlling radiation
damage on a single atom level. In this contribution it is shown that
extraordinary signal-to-noise levels can be obtained in single lattice
images that even allow for the detection of individual carbon atoms
well above noise [3]. As a result it becomes possible to study atom
clusters on a single atom level and to control radiation damage atom by
atom. We find that radiation damage affects weakly bound atoms at
crystal surfaces first and show that single carbon, germanium and gold
atoms can be kept in place or be registered if removed in experiments
utilizing acceleration voltages between 80 kV and 300 kV. In particular
it is now possible to simultaneously image the presence of a heavy atom
and a light atom, which is of interest for investigating catalytical
processes.
[1] The TEAM project is supported by the Department of Energy, Office
of Science, Basic Energy Sciences. NCEM is supported by the Department
of Energy under Contract # DE-AC02-05CH11231.
[2] C. Kisielowski, B. Freitag, M. Bischoff, H. van Lin, S. Lazar, G.
Knippels, P. Tiemeijer, M. van der Stam, S. von Harrach, M.
Stekelenburg, M. Haider, S. Uhlemann, H. Muller, P. Hartel, B. Kabius,
D. Miller, I. Petrov, E. A. Olson, T. Donchev, E. A. Kenik, A. Lupini,
J. Bentley, S. Pennycook, I.M. Anderson, A. M. Minor, A. K. Schmid, T.
Duden, V. Radmilovic, Q. Ramasse, M. Watanabe, R. Erni, E. A. Stach, P.
Denes, and U. Dahmen. Detection of single atoms and buried defects in
three dimensions by aberration-corrected electron microscopy with 0.5
angstrom information limit. In review, 2008.
[3] J. C. Meyer, C. Kisielowski, R. Erni, M.D. Rossell, A. Zettl,
Direct imaging of lattice atoms and topological defects in graphene
membranes, NanoLetters, in press, 2008