Inelastic Electron Tunneling Spectra of Neutral and Basic Zinc Dithiophosphates on Native Aluminum Oxide Surfaces

Abstract

Inelastic electron tunneling (IET) spectra of pure neutral and basic isopropyl, isobutyl, and p-t-octyl phenyl ZnDTPs are reported. These pure compounds were specially synthesized in order to examine the IET spectra of the neutral and basic ZnDTP salts separately. This is of interest since the commercial ZnDTPs, whose spectra were reported previously, consist of mixtures of neutral and basic ZnDTP salts for all types of primary, secondary, and aryl ZnDTPs used today. Thus, an examination of each representative pair was made, i.e. isobutyl (primary), isopropyl (secondary), and p-t-octyl phenyl (aryl), in order to investigate these structural modifications on the IET spectra and relate the data to the adsorption characteristics. Generally, the conclusions drawn are in agreement with those from previous work on commercial ZnDTPs. Aryl ZnDPTs dissociate on adsorption, and do not retain the P= S group. Alkyl ZnDTPs retain the P=S group on adsorption. Differences among the neutral and basic forms of the pure al...