Water is the most abundant species observed in interstellar and cometary ices, and therefore it is important to understand its physical and chemical evolution in these environments. Heat and radiation drive the desorption of water ice, and photodesorption is an important process for explaining the gas-phase abundances that are observed in extremely cold regions, such as cold cores and the outer regions of protoplanetary disks, where thermal desorption is unlikely. Furthermore, the photodesorption yield of gas-phase OH and OD from the photodissociation in water ice is not consistent throughout the literature. To shed light on these processes we are developing a laboratory technique to study the thermal desorption and photodesorption of laboratory analogs of interstellar and cometary ices using submillimeter spectroscopic detection of the desorbed species above the ice, as opposed to the more typical method of mass spectrometry. While mass spectrometry has impressive limits of detection, it is usually unable to distinguish between species of the same mass (e.g. OD and H2O), whereas submillimeter spectroscopy can be used to distinguish between them using their unique rotational spectral fingerprints. Our laboratory spectra are also directly comparable to remote observational data collected via millimeter/submillimeter telescopes. This laboratory technique will be briefly discussed along with new results of thermal- and Lyman-α photo-processed H2O and D2O ices.

Laboratory submillimeter spectrscopic analysis of desorbed H2O and D2O ices

2019 Fall National Meeting

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