Degradation of poly(vinyl chloride) and nitrocellulose in XPS

Measurements have been made of the degradation rates for poly(vinyl chloride) (PVC) and nitrocellulose with cellulose acetate (NC) in x-ray photoelectron spectroscopy. These materials form part of earlier studies published by others to evaluate instrumental degradation factors. In the earlier studies, results showed significant scatter such that the relative rates varied significantly from instrument to instrument. It is shown here that this variation could arise from different levels of adventitious electrons in the different instruments as well as different layer thicknesses exhibiting the degradation in PVC and NC. The former depends on electrodes in the system and the neutralizing parameters, whereas the latter causes the relative degradation rates to depend on the angle of emission of the detected electrons. These will have varied from laboratory to laboratory in the earlier study. The present study leads to simple recommendations for operating conditions to reduce the degradation effects observed. Crown Copyright (C) 2003.