Interaction of 0.2- to 4.0-ev Electron Beams with Cleaved MgO

Abstract

An attempt was made to determine the absorption coefficient δ_a for electrons incident on MgO and irradiated MgO for the impacting energy range, 0.2 ev through the conduction band (about 7.3 ev). It was found that electron trapping was so severe that the crystals would not thermally discharge at temperatures below 350°C. Consequently, the charged crystals were neutralized by a less satisfactory technique, high energy electron bombardment. δ_a was reproducible only at energies less than 4 ev. Sharp slope changes were observed at about 1.80 and 3.00 ev. These ``lines'' correspond to luminescence spectra obtained for catalytic recombination of N on MgO. Since slow electrons have been observed to interact predominantly with crystal defects, the data support the suggestion that defects can play a dominant role in catalytic reactions.