Astigmatic electron diffraction imaging: a novel mode for structure determination.

In a conventional transmission electron microscope, stigmators are used to correct for the effects of axial astigmatism in the diffraction lens. It seems feasible that these same stigmators could also be used to form a series of 'astigmatic' diffraction patterns. It is shown how this series of diffraction patterns could then be used to perform exit-surface wavefunction reconstruction. This has the advantage that the diffraction patterns are not resolution limited by the objective aperture as are images when performing exit-surface wavefunction reconstruction from a focal series. A scheme for carrying out phase reconstruction from a series of astigmatic diffraction patterns in an electron microscope is presented.

[1]  L J Allen,et al.  Exit wave reconstruction at atomic resolution. , 2004, Ultramicroscopy.

[2]  J R Fienup,et al.  Phase retrieval algorithms: a comparison. , 1982, Applied optics.

[3]  Leslie J. Allen,et al.  Phase retrieval from series of images obtained by defocus variation , 2001 .

[4]  J. Miao,et al.  Direct determination of the absolute electron density of nanostructured and disordered materials at sub-10-nm resolution , 2003 .

[5]  J. Miao,et al.  Phase retrieval of diffraction patterns from noncrystalline samples using the oversampling method , 2003 .

[6]  I. Robinson,et al.  Reconstruction of the shapes of gold nanocrystals using coherent x-ray diffraction. , 2001, Physical review letters.

[7]  Leslie J. Allen,et al.  Exit wave reconstruction using soft X-rays , 2004 .

[8]  W. O. Saxton.  What is the focus variation method? Is it new? Is it direct? , 1994 .

[9]  J. N. Chapman,et al.  The application of iterative techniques to the investigation of strong phase objects in the electron microscope , 1975 .

[10]  M. Teague.  Deterministic phase retrieval: a Green’s function solution , 1983 .

[11]  R. Ritchie,et al.  Imaging of the crystal structure of silicon nitride at 0.8 Ångstrom resolution , 2002 .

[12]  J. Zuo,et al.  Atomic Resolution Imaging of a Carbon Nanotube from Diffraction Intensities , 2003, Science.

[13]  K. Nugent,et al.  Noninterferometric phase imaging with partially coherent light , 1998 .

[14]  K. Nugent,et al.  Unique phase recovery for nonperiodic objects. , 2003, Physical review letters.

[15]  Fang-hua Li,et al.  Image processing in high-resolution electron microscopy using the direct method.I.Phase extension , 1985 .

[16]  J. G. Walker.  The Phase Retrieval Problem , 1981 .

[17]  U Weierstall,et al.  Image reconstruction from electron and X-ray diffraction patterns using iterative algorithms: experiment and simulation. , 2002, Ultramicroscopy.

[18]  Sayre,et al.  On possible extensions of X-ray crystallography through diffraction-pattern oversampling , 2000, Acta crystallographica. Section A, Foundations of crystallography.