High-resolution phase contrast imaging, aberration corrections, and the specifics of nanocrystals

High-resolution phase contrast imaging, aberration corrections, and the specifics of nanocrystals

Pages 450-459, in Methods and applications in crystallographic computing, S.R. Hall and T. Ashida, Proc. Intern. Summer School on Crystallographic Computing, Kyoto, 18-27 August 1983

modified after H. Rose 19 th century 0.15 nm 20 th century 21 st century Aberration corrected TEM Tecnai F20 ST & Cs corrector Bohr radius. 4 _ Z STEM 1 4 res Scherzer 0 C λ s 1 4 s res Scherzer _ Phase HRTEM 0. 67 C λ 3 4 3 4 Point-to-point resolution [Å -1 ] 0.2 nm Tecnai F20 ST Transmission Electron Microscope Light Microscope (theory) Menter Scherzer (theory) far field resolution limit 250 nm 1 nm 10 nm 100 nm 1 µm electron phase or Z- contrast imaging for optimal C s, large-tilt range goniometer (preferentially with an extra degree of freedom to tilt) and on-line power spectra of images will lead to (discrete) atomic resolution tomography of nanocrystals just one application of image-based nanocrystallography by means of transmission electron goniometry

H. Rose, Correction of aberrations, a promising means for improving the spatial and energy resolution of energy-filtering electron microscopes, Ultramicroscopy 56 (1994) 11-25 In materials science tomographic methods will become important at a resolution limit which allows one to use different crystal orientations.

All atoms are roughly of the same size, all bond length in chemical compounds are in the range 0.12 to 0.25 nm!!! (except H-bonds) 0.053 nm, Bohr radius So with enough image resolution we basically see the equivalents of ball (and stick) models From W.F. Smith, Foundations of Materials Science, 3 rd edition, McGraw Hill, 2004

Christian Kisielowski et al., http://ncem.lbl.gov/frames/diamondhlt.pdf

3.2. Atomic resolution tomography & direct space goniometry = discrete atomic resolution tomography Numbers of crystal orientations available as a function of a given point to point resolution for a given material - without taking symmetry into account (after NSF Report on Atomic Resolution Imaging) 0.2 0.16 0.1 0.06 structural nm nm nm nm prototype Diamond 1 1 2 9 diamond Aluminum 2 2 6 10 Cu-type Silicon 1 2 7 13 diamond Iron (BCC) 1 1 4 12 W-type Iron (FCC) 1 2 5 12 Cu-type Tungsten 1 1 5 13 W-type What does one need to identify the crystallographic phase of an individual nanocrystal? PhD thesis Direct Space (Nano)Crystallography via High-Resolution Transmission Electron Microscopy by Wentao Qin, supervisor Philip B. Fraundorf W. Qin, P. Fraundorf, Ultramicroscopy 94 (2003) 245 (similar to P. Möck, patents DE 4037346 A1 and DD 301839 A7, priority date 21. 11. 1989, whole field invented by P. Fraundorf, Ultramicroscopy 6 (1981) 227 and 7 (1981) 203, only about 50 papers in this field worldwide

JEOL JEM 1250 TEM, max acceleration voltage 1.25 MeV, increasing Scherzer point to point resolution by about a factor of 2, to about 0.1 nm Cost about $ 25 million, needs its own special building, some 10 to 15 m high, problem of beam damage On the other hand, a modern 300 kv TEM/STEM with C s correctors or a modern 200 kv TEM/STEM with C s and C c corrector (and monochromator) and all analytical gadgets may cost less than $ 2.5 million for the same spatial resolution and significantly reduced beam damage

Correction of lens aberrations, mainly C s to some extend C c by monochromators Directly interpretable (point or Scherzer) resolution 0.24 nm Directly interpretable resolution approaching information limit (point or Lichte resolution) 0.11 nm Cs corrector Triebenberg Laboratory Technical University Dresden: http://www.physik.tu-dresden.de/isp/member/wl/tbg/equipment/equipment.htm

In aberration-corrected times information limit, 0.07 nm, becomes new key specification of a base microscope system!! Au {444} has been detected in polycrystalline samples HRTEM line resolution: 0.0589 nm TEAM microscopes: FEI Titan TM 80-300, it s a S/TEM or (S)TEM! An incredible 5.4 mm space for tilting crystals in objective lens pole piece!!

Condenser-C s corrected FEI Titan 80-300, {335}-Si possesses spacing of 0.083 nm (but not occupied by atoms,)

J.F. Banfield and H. Zhang, Nanoparticles in the Environment, in Nanoparticles and the Environment, pp. 1-58, by J.F. Banfield and A. Navrotsky, Reviews in Mineralogy & Geochemsitry, Vol. 44, Mineralogical Society of America, P.H. Ribbe Series Editor