Work-Function Dependence of Negative-Ion Production during Sputtering

Abstract

A systematic study was made of negative-ion formation by sputtering from a Mo(100) surface with and without adsorbate layers. Correlation with the work-function change when the surface electronic state was modified by a Cs overlayer reveals a possible tunneling mechanism. Tunnel barrier widths and heights were estimated for ${\mathrm{Mo}}^{\ensuremath{-}}$, ${\mathrm{O}}^{\ensuremath{-}}$, ${\mathrm{H}}^{\ensuremath{-}}$, and ${\mathrm{D}}^{\ensuremath{-}}$ from the experimental data.