FOCUSING OF ELECTRONS REFLECTED FROM A CRYSTAL WITH LOSS OF ENERGY

A study is made of the features arising in the spatial distributions o f reflected electrons as a result of a focusing effect. Experiments ar e conducted on single-crystal Mo (100) with primary electron energies of 0.5-2 keV and detection of electrons which lose fixed amounts of en ergy up to 300 eV. An analysis of the data establishes the dependence of the electron focusing efficiency on the amount of energy loss. It i s shown that when electrons are reflected with single losses through p lasmon excitation, the magnitude of the effect is determined mainly by the average number of scattering atoms encountered by an electron alo ng its path to the surface. When the energy losses are high, defocusin g owing to multiple elastic and inelastic scattering of the electrons is found to predominate. (C) 1998 American Institute of Physics. [S106 3-7842(98)02306-X].