ELECTRON-STIMULATED NEUTRAL AND ION EMISSION FROM SINGLE-CRYSTAL NANO3

Quadrupole mass spectrometry of the neutral products accompanying irra diation of single crystal NaNO3 with a pulsed beam of 1-3 keV electron s shows intense NO and O-2 emissions and smaller amounts of Na and NO2 . Time-of-flight and intensity measurements as a function of pulse wid th and temperature are consistent with NO emission via a thermally ass isted, electronic emission mechanism. The activation energy for the th ermally assisted process is about 0.11 eV-similar to the excitation en ergies for internal vibrational modes of the NO3- anion. The emission of neutral O-2 involves fairly complex reactions with dissociation pro ducts and is also thermally assisted at temperatures above 380 K. Mass -selected ion emission measurements indicate copious H+ emission, wher e the temperature dependence of the H+ intensity is similar to that of NO. We propose that H+ emission is limited by the density of appropri ate surface defect sites, and that these sites are directly related to NO3- dissociation.