|
VOLUME 62 (1995) | ISSUE 3 |
PAGE 252
|
How the atomic structure of a crystal can be seen without a high-resolution microscope
Indenbom V. L., Tochilin S. B.
The method of high-resolution electron microscopy (HREM) has been widely used in the last few years to study the atomic structure of crystalline materials and crystal lattice defects. The possibilities of HREM are limited by spherical aberration. As a result, even the best microscopes have a resolution of no better than 1-2 A, i.e., much greater than the electron wavelength, which for characteristic values of the accelerating voltage 0.1-1.0 MeV reaches 0.038 and 0.012 A, respectively. The resolution can be increased by 1.5 orders of magnitude by using, instead of HREM, dynamic electron diffraction patterns and by investigating not only the coordinates of the reflections, but also how the average intensity of the reflections along the radius of the electron diffraction pattern decreaes (primarily the width of the electron diffraction pattern, which determines the width of the peaks of the Bloch waves on the exit surface of the transilluminated foil). As an example, a resolution of the order of 0.10 A is given for gold with transmission along (111). © 1995 American Institute of Physics.
|
|