The Effect of UV Emission Spectrum and Absorption Cross Section on Photodesorption of CO₂ Ice Analogs

Ni-En Sie^1*, G. M. Muñoz Caro², Zhao-Hui Huang¹, Yu-Jung Chen¹

¹Department of Physics, National Central University, Taoyuan City, Taiwan
²Centro de Astrobiología, INTA-CSIC, Madrid, Spain

* Presenter:Ni-En Sie, email:angelnnrita@gmail.com

In the interior of dense clouds, gaseous molecules collide with dust grains and accrete to form ice mantles because of the extremely low temperature of the dust grain surface, which is near 10 K. Desorption of ice molecules induced by cosmic rays and secondary ultraviolet (UV) photons is expected to contribute to the observed gas phase abundances toward cold regions where thermal desorption is inhibited. In this work, we performed a complete quantitative calibration of quadrupole mass spectrometer (QMS) to convert the ion current of desorbing species into column density units for CO₂ ice irradiated by Microwave-Discharge Hydrogen-flow Lamp (MDHL). In addition, we demonstrated that the discrepancy of the photodesorption yield between Martín-Doménech et al. (2015) and this study is related to emission spectrum of MDHL and the UV absorption cross section.

Keywords: Photodesorption yield, Quadrupole mass spectrometer, UV absorption cross section, Carbon dioxide