COINCIDENCE ELECTRON-SPECTROSCOPY OF W(100) IN THE THRESHOLD-ENERGY REGION

The simultaneous emission of two electrons from W(100) after excitation by a normally incident primary electron is studied as a function of the primary electron energy (1022 eV relative to the Fermi level) and emission angle. We found that the coincidence rate as a function of the primary electron energy had a low-intensity tail in the region below 18 eV with an energy threshold at 11.512 eV. The most probable angle between two scattered electrons was found to be about 80°at 20.6-eV primary electron energy. The maximum sum energy of correlated electrons is found to agree with the energy conservation law limit. Experimental results are in fair agreement with calculations based on a two-parabolic-band approximation. © 1995 The American Physical Society.