Quantitative Analysis of Thermal Desorption Spectra: Chemisorption of Carbon Monoxide on Tungsten

Abstract

Numerical analysis of the line shapes of thermal desorption spectra for CO on polycrystalline tungsten has been carried out. The results show that within the β phase there are at least six chemisorption substates; desorption from five of these states is a simple, first-order process. We have demonstrated that the desorption technique is capable of resolving surface states whose heats of activation for desorption differ by as little as 4 kcal/mole. The experimental frequency factors for the five first order states increase with increasing activation energy. All the results can be interpreted as indicative of a highly directional bonding that is not closely related to the crystallographic anisotropy of the tungsten surface.