Surface reactions on interstellar grains are prerequisite for the formation of various interstellar molecules such as H2, H2O, and CH3OH. In addition, grain-surface reactions are highly expected to play a role for deuterium-enrichment of interstellar molecules via hydrogen (H)-deuterium (D) substitution reactions. In the present study, we performed laboratory experiments on the deuteration of hydrogen sulfide, H2S, by H-D substitution reactions on amorphous solid water at 10 K. When H2S reacts with D atoms, the D atom abstracts an H atom from the H2S as follows: H2S + D → HS + HD. The formed HS radical will further react with another D atom, which is expected to result in the formation of mono-deuterated hydrogen sulfide (HDS): HS + D → HDS. Repetition of this process would result in the formation of fully deuterated sulfide, D2S. We confirmed the formation of HDS and D2S by in-situ FTIR measurements and temperature-programmed desorption experiments. Further results and discussion will be presented about the reaction kinetics and comparison with the deuterium-enrichment of hydrogen sulfide observed in space.

Experimental studies on the surface reaction of hydrogen sulfide with deuterium atoms on amorphous solid water at 10 K

255th National Meeting (2018)

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