open access

https://hdl.handle.net/2115/79283

An Experimental Study of Chemical Desorption for Phosphine in Interstellar Ice

英語

Pre-biotic astrochemistry

2020-08

IOP Publishing

Astrophysical journal letters

898(2)

L52

Phosphine (PH3), an important molecule for the chemistry of phosphorus (P)-bearing species in the interstellar medium (ISM) is considered to form primarily on interstellar grains. However, no report exists on the processes of PH(3)formation on grains. Here, we experimentally studied the reactions of hydrogen (H) atoms and PH(3)molecules on compact amorphous solid water, with a particular focus on the chemical desorption of PH(3)at 10-30 K. After exposure to H atoms for 120 minutes, up to 50% of solid PH(3)was lost from the icy surface. On the basis of experiments using deuterium atoms, it was concluded that the loss of PH(3)resulted from chemical desorption through the reactions PH3+ H -> PH2 + H(2)and/or PH2+ H -> PH3. The effective desorption cross-section was similar to 5 x 10(-17)cm(2), which is three times larger than that of hydrogen sulfide measured under similar experimental conditions. The present results suggest that the formation of PH3, and possibly PH(2)and PH, followed by their desorption from icy grains, may contribute to the formation of PN and PO in the gas phase, and thus may play a role in the P chemistry of the ISM.

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Creative Commons Attribution 4.0 International

2041-8205