Spectroscopy and Processing of Interstellar Ice Analogs

Recent results from the Raymond and Beverly Sackler Laboratory for Astrophysics on spectroscopy and processing of interstellar ice analogues are summarized. This includes thermal desorption studies of pure, layered and mixed CO, N2 and O2 ices, and infrared spectroscopy and heating of CO-CO2, CO-H2O, CO-HCOOH, CO-CH4 and CO-CH3OH layered and mixed ices. Laboratory data of CO-surface adsorbates show good agreement with the unidentified 2175 cm-1 interstellar feature. Complementary ab initio quantum chemical calculations and molecular dynamics simulations have been performed to provide insight into the gas-grain interactions and interstellar ice processing. This includes the first molecular dynamics study of the photodissociation of water ice and the corresponding photodesorption efficiencies. The relevance of these data in the analysis of astronomical data is emphasized throughout.