X-ray induced desorption and photochemistry in CO ice

TL;DR

This study investigates how X-ray irradiation causes desorption and chemical changes in CO ice, revealing mechanisms for neutral, cation, and anion release relevant to astrochemistry.

Contribution

It provides detailed quantification of X-ray induced desorption of various species from CO ice and explores the underlying photochemical mechanisms.

Findings

Neutral CO desorption quantified

Large cations desorb upon X-ray irradiation

O$^-$ and C$^-$ are the only detected anions

Abstract

We report an investigation of X-ray induced desorption of neutrals, cations and anions from CO ice. The desorption of neutral CO, by far the most abundant, is quantified and discussed within the context of its application to astrochemistry. The desorption of many different cations, including large cations up to the mass limit of the spectrometer, are observed. In contrast, the only desorbing anions detected are O$^-$ and C$^-$. The desorption mechanisms of all these species are discussed with the aid of their photodesorption spectrum. The evolution of the X-ray absorption spectrum shows significant chemical modifications of the ice upon irradiation, which along with the desorption of large cations gives a new insight into X-ray induced photochemistry in CO ice.