Gravity seminar : Alicja Bulik, University Autònoma de Barcelona — TITLE: Quantum chemical insights into the adsorption of interstellar icy species and their spectral features

In the coldest, densest regions of the Interstellar Medium (ISM) dust grains are covered by thick ice mantles dominated mainly by water. Although, more than 300 species have been detected in the gas phase of the ISM by their rotational emission lines within the radiofrequency range, only a few were found in interstellar ices, e.g. CO, CO2, NH3, CH3OH, CH4 and OCS, by means of infrared (IR) spectroscopy. Observations of ices require a background-illuminating source for absorption, constraining the available sight lines for investigation. Further challenges arise when comparing with laboratory spectra due to the influence of temperature, ice structure and the presence of other species. In the era of IR observations provided by the James Webb Space Telescope (JWST), it is crucial to provide reference spectral data confirming JWST’s assigned features. In my work I will addresses the adsorption of the aforementioned species on water ice surfaces and their IR spectral features by means of quantum chemical computations grounded on the density functional theory (DFT) methodology, which is known to give reliable results for vibrational frequency calculations and IR spectra simulation. Binding energies and IR spectral data will be presented in the context of experimental spectra of ices and the new findings from the JWST, which have already proven to be insightful thanks to its unmatched sensitivity.