Affiliation:
1. Université Paris-Saclay CNRS Institut des Sciences Moléculaires d'Orsay 91405 Orsay France
2. Laboratoire d'Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA) Sorbonne Université Observatoire de Paris PSL University CNRS 4 Pl. Jussieu 75005 Paris France
Abstract
AbstractX‐Ray irradiation of interstellar ice analogues has recently been proven to induce desorption of molecules, thus being a potential source for the still‐unexplained presence of gaseous organics in the coldest regions of the interstellar medium, especially in protoplanetary disks. The proposed desorption mechanism involves the Auger decay of excited molecules following soft X‐ray absorption, known as X‐ray induced electron‐stimulated desorption (XESD). Aiming to quantify electron induced desorption in XESD, we irradiated pure methanol (CH3OH) ices at 23 K with 505 eV electrons, to simulate the Auger electrons originating from the O 1s core absorption. Desorption yields of neutral fragments and the effective methanol depletion cross‐section were quantitatively determined by mass spectrometry. We derived desorption yields in molecules per incident electron for CO, CO2, CH3OH, CH4/O, H2O, H2CO, C2H6 and other less abundant but more complex organic products. We obtained desorption yields remarkably similar to XESD values.
Subject
Physical and Theoretical Chemistry,Atomic and Molecular Physics, and Optics