Dissociative self-surface ionization of alkali-metal halides

Abstract

The emission rates ( n o and n ±) of neutral alkali halide molecules (MX o) and of thermal positive or negative ions (M + or X −) produced on the self surface of polycrystalline alkali halide (roughly 10 3 molecular layers) on a platinum plate (2.0 mm 2) were measured simultaneously as a function of surface temperature (about 700–800 K). Quantitative relations between n ±/√ n o and nine factors governing the rates were theoretically derived, and both effective work function and fractional surface area for emitting M + or X − were determined, thereby indicating that M +, X −, and MX o were emitted from different surface sites with quite different values in work function.