High-resolution spectroscopy is currently the only method used in the remote sensing of trace complex molecules in the gases of star-forming regions, planet-forming disks, and planetary and cometary atmospheres. Many of the observed molecules are created in ices and then released into the gas phase; however, most experimental studies of ice chemistry employ spectroscopic detection only in the solid phase, or through mass spectrometry that may not be sensitive to transient species (radicals and/or ions) or isomers. Such studies therefore do not fully follow the physical and chemical routes to the formation of trace gas species that may be important in space.  In order to fully understand the chemistry that results from desorption, we have built an experimental system to study the chemistry above the surfaces of laboratory ice samples during heating and/or photoprocessing. The new experimental setup is designed to simulate interstellar, planetary, and cometary ices and detect the sublimated or sputtered trace species with millimeter and submillimeter rotational spectroscopy -- the same technique used for remote observations of gases. This is accomplished by performing in situ spectroscopic measurements on gases released by an ice sample during thermal or photoprocessing. We have obtained proof-of-concept for this experiment by detecting water vapor sublimating from a pure water ice and methanol vapor sublimating from a pure methanol ice. This newly-established technique can be applied to the study of interstellar, planetary, and cometary ice analogs.  We will report here on the experimental design, proof-of-concept experiments, and initial results for pure and mixed ices containing water and methanol.

Rotational spectroscopy as a probe for gas-phase products of thermal- and photo-processed ices

2019 Fall National Meeting

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