Abstract

Although UV photon-induced CO ice desorption is clearly observed in many cold regions of the Universe as well as in the laboratory, the fundamental question of the mechanisms involved at the molecular scale remains debated. In particular, the exact nature of the involved energy transfers in the indirect desorption pathway highlighted in previous experiments is not explained. Using abinitio molecular dynamics simulations, we explore a new indirect desorption mechanism in which a highly vibrationally excited CO (v=40) within an aggregate of 50 CO molecules triggers the desorption of molecules at the surface. The desorption originates first from a mutual attraction between the excited molecule and the surrounding molecule(s), followed by a cascade of energy transfers, ultimately resulting in the desorption of vibrationally cold CO (∼95% in v=0). The theoretical vibrational distribution, along with the kinetic energy one, which peaks around 25meV for CO with low rotational levels (v=0, J<7), is in excellent agreement with the results obtained from VUV laser induced desorption (157nm) of CO (v=0, 1) probed using REMPI.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call