DIRECT ATOMIC IMAGING OF AG(100) AND AG(111) BY INVERTING QUASI-ELASTICALLY SCATTERED ELECTRON-DIFFRACTION PATTERNS

Direct imaging of three-dimensional atomic structure of Ag(100) and Ag(111) surfaces by Fourier-transforming the multiple-energy diffraction patterns of quasielastically scattered electrons is demonstrated experimentally. The holographic images obtained with an integral-energy phase-summing method are of high fidelity and free from artifacts. The resolution of the atomic images is 1 in all spatial directions. The atoms down to three layers below the emitters are three dimensionally imaged. The contribution from backward-scattering and forward-scattering oscillations can be separately observed by varying the energy range used in Fourier transformation. The surface sensitivity can be enhanced by using an off-normal-incident geometry. With a limited energy range (200 eV) used in Fourier transformation, the atoms behind the emitter in the backward direction are observed. © 1995 The American Physical Society.