Chemical Changes of Evaporated a-C Films upon UV Ashing, Hydration, and Drying

Abstract

Evaporated amorphous carbon (a-C) films, used as a support in electron microscopy, are studied by FTIR spectroscopy. During preparation of biological specimens, such films are subject to UV ashing (UVA), hydration, and drying. The chemistry of evaporated a-C films is investigated, based on removing a very thin carbon layer by UVA, and measuring its absorbance spectrum. A simple model is proposed for analyzing such spectra. The peaks which are a result of UVA, of as-prepared a-C films, as well as of hydration and drying of such films are identified, and their behavior is discussed. The chemical reactions, arising during UVA, hydration, and drying of our evaporated a-C films, are determined. It is clarified, that these processes introduce chemical changes exclusively on the surface of our film, and not in its volume.