Photochemical Processing of CO tex2html_wrap_inline18 and CO tex2html_wrap_inline18 -water Ices by X-radiation

B. L. Lutz, T. R. Dillingham, D. M. Cornelison, W. R. Ruppart, S. C. Tegler (NAU Physics and Astronomy)

Chemical changes that occur during the photoprocessing of cosmically abundant ices have important implications in atmospheric physics and planetary astronomy. In this paper, we present results of a study of CO tex2html_wrap_inline18 and CO tex2html_wrap_inline18 -water ices to investigate the chemical changes that are induced by X-radiation. The CO tex2html_wrap_inline18 and CO tex2html_wrap_inline18 -water ices were formed at liquid nitrogen temperature in an ultra high vacuum environment and continuously bombarded with high intensity K tex2html_wrap_inline30 radiation for up to ten hours in the analysis chamber of an X-ray photoelectron spectrometer (XPS). Significant changes in the core level line shapes associated with these ices were found in the X-ray photoelectron spectra recorded during the processing. A quadrupole mass spectrometer was used to monitor the species evolving from the surface during the processing, and the results were correlated with XPS results. Possible mechanisms associated with the photochemical processing are discussed.

This research was supported in part by the NAU Organized Research Program and the NASA Origins of Solar System Program.