UPS investigation of poorly crystallized MoS2

Abstract

We have performed photoemission studies on samples of poorly crystallized MoS2 prepared in situ by thermal decomposition of (NH4)2MoS4 in a UHV-compatible chamber under mixed H2S/H2 gas conditions. The results reveal new electronic states which are not present on crystalline MoS2. These states are observed as a band tail above the dz2 band of MoS2. These tail states are presumably ‘‘chemically active’’ as shown by reversible oxygen adsorption–desorption.