Can interstellar H2S be formed via gas-phase reactions?  Calculations concerning the rates of the ternary and radiative association reactions between HS+ and H2.
Based on laboratory work involving the ternary association reaction of HS+ and H2 at 80 K, we have estimated the rate of the analogous radiative association reaction under interstellar conditions.  Both the ternary and radiative association reactions appear to occur via a mechanism in which the electronic spin of the H3S+ complex changes before the complex is stabilized.  Although this spin change is of low probability, it leads to a radiative association rate coefficient at 80 K of 7 x 10(-16) cm3 s-1 if radiative stabilization occurs at a rate of 10(3) s-1.  This value of the radiative association rate coefficient at 80 K is large enough to lead to the observed abundance of H2S in the ambient ridge source in Orion.
Herbst
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Department of Physics, Duke University, Durham NC 27706, USA.
DeFrees
D J
DJ
Koch
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W
D005118:Extraterrestrial Environment; D006371:Helium; D006859:Hydrogen / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000737:chemistry*; D008433:Mathematics; D008956:Models, Chemical; D013455:Sulfur / Q000737:chemistry*
D006371:Helium; D013455:Sulfur; D006859:Hydrogen; D006862:Hydrogen Sulfide