Anomalous temperature dependence of the desorption of excited sodium atomsinduced by ion bombardment of sodium fluoride crystals

Abstract

We have observed anomalous temperature dependence in the ion-induced desorption of excited sodium atoms from sodium fluoride crystals. The fluorescence yield of the 3p-3d transition at 8195 \AA{}, and the 3p-4d transition at 5688 \AA{} increases steadily with temperature; however the yield of sodium doublet 3s-3p transition displays a pronounced maximum in the region of 160 \ifmmode^\circ\else\textdegree\fi{}C. Fluorescence yields are also found to be nonlinear as a function of beam current at room temperature. To explain these experimental results, we propose a mechanism that involves electron transfer between the desorbing atoms and the bombarded surface.