posted on 2022-12-19, 15:45authored byJia Wang, Joshua H. Marks, Lotefa B. Tuli, Alexander M. Mebel, Valeriy N. Azyazov, Ralf I. Kaiser
Since the observation of the first
sulfur-containing molecule,
carbon monosulfide (CS), in the interstellar medium (ISM) half a century
ago, sulfur-bearing species have attracted great attention from the
astrochemistry, astrobiology, and planetary geology communities. Nevertheless,
it is still not clear in which forms most of the sulfur resides in
molecular clouds, an unsolved problem referred to as “sulfur
depletion”. Reported herein is the formation of thioformic
acid (HCOSH)the simplest thioacidin interstellar ice
analogues containing carbon monoxide (CO) and hydrogen sulfide (H2S) at 5 K. Utilizing single photoionization reflectron time-of-flight
mass spectrometry and isotopically labeled molecules, thioformic acid
molecules were selectively photoionized in the temperature-programmed
desorption phase. These studies unravel a key reaction pathway to
thioformic acid, an organic molecule recently detected toward the
giant molecular cloud G+0.693–0.027 and the hot core G31.41+0.31,
thus shedding light on interstellar sulfur chemistry.