paper

On The Photodesorption of CO $_{2}$ Ice Analogues: The Formation of Atomic C in The Ice and the Effect of The VUV Emission Spectrume

arXiv:2001.01590 · doi:10.3847/1538-4357/ab06be

Abstract

CO $_{2}$ ice has a phase transition at 35 K when its structure changes from amorphous to crystalline. Using Reflection absorption Infrared Spectroscopy (RAIRS), Ãberg et al. observed that the photodesorption yield of CO $_{2}$ ice deposited at 60 K and irradiated at 18 K is 40% lower than that of CO $_{2}$ ice deposited and irradiated at 18 K. In this work, CO $_{2}$ ices were deposited at 16-60 K and UV-irradiated at 16 K to rule out the temperature effect and figure out the relationship between photodesorption yield and ice structure. IR spectroscopy is a common method used for measurement of the photodesorption yield in ices. We found that undetectable C atoms produced in irradiated CO $_{2}$ ice can account for 33% of the amount of depleted CO $_{2}$ molecules in the ice. A quantitative calibration of QMS was therefore performed to convert the measured ion current into photodesorption yield. During various irradiation periods, the dominant photodesorbing species were CO, O $_{2}$ , and CO $_{2}$ , and their photodesorption yields in CO $_{2}$ ices deposited at different temperature configurations were almost the same, indicating that ice morphology has no effect on the photodesorption yield of CO $_{2}$ ice. In addition, we found that the lower desorption yield reported by MartÃn-DomÃ©nech et al. is due to a linear relationship between the photodesorption yield and the combination of energy distribution of Microwave-Discharge Hydrogen-flow Lamp (MDHL) and UV absorption cross section of ices.

11 pages, 11 figures

On The Photodesorption of CO2​ Ice Analogues: The Formation of Atomic C in The Ice and the Effect of The VUV Emission Spectrume

Abstract

On The Photodesorption of CO $_{2}$ Ice Analogues: The Formation of Atomic C in The Ice and the Effect of The VUV Emission Spectrume