X-ray induced degradation during XPS analysis of dicarboxylic acid powders

Abstract

It is widely recognized that exposure to X-rays during XPS analysis can decompose different materials, resulting in mass loss and changes in chemical composition. These effects are evident in the near-edge X-ray absorption structure spectra of dicarboxylic acid powders, posing a fundamental limit to sensitivity for surface chemical analysis. Understanding the chemistry and kinetics of radiation decomposition is necessary for the accuracy and validation of XPS analysis on dicarboxylic acids. Here we evaluate the impact of X-ray exposure on characterizing chemical changes in three different dicarboxylic acids with varying aliphatic carbon chain lengths. From this investigation we propose straightforward correlations relating the tendency for radiation-induced decomposition based on the chemical structure of the acids. We employed two types of spectra, those acquired with minimal interaction (snapshot) and high-resolution spectra obtained over an extended period, to show that normal analysis conditions are likely to degrade these type of materials.