Presentation #134.04 in the session Laboratory Astrophysics (LAD) Division Meeting: The Salty Solar System II.
Interstellar molecules with symmetric hydrogen nuclei exist in ortho and para states and the ortho-to-para ratios (OPRs) are thought to provide information about thermal and chemical history. The OPR of formaldehyde (H2CO) is sometimes used to predict whether this compound formed on a cold interstellar grain or in the gas phase at warmer temperatures, but the full meaning of the OPRs detected in interstellar clouds are still a topic of debate. This work aims to unravel more information about the OPR of formaldehyde (H2CO) formed on icy interstellar grains through laboratory experiments using SubLIME, the Sublimation of Laboratory Ices Millimeter/submillimeter Experiment. The OPR of formaldehyde (H2CO) was measured using submillimeter spectroscopy after low-temperature formation by ultraviolet photolysis of interstellar ice analog samples containing water (H2O), carbon monoxide (CO), and/or methanol (CH3OH). The experimental approach and preliminary results will be discussed.