Experimental and Computational Studies on the Physicochemical Behavior of Phosphine Induced by Reactions with H and D Atoms on Interstellar Ice Grains

Nguyen Thanh; Oba Yasuhiro; Sameera W. M. C.; Kouchi Akira; Watanabe Naoki

Title	en Experimental and Computational Studies on the Physicochemical Behavior of Phosphine Induced by Reactions with H and D Atoms on Interstellar Ice Grains
Creator	en Nguyen, Thanh NRID 1000040846599 en Oba, Yasuhiro en Sameera, W. M. C. NRID 1000090791278 en Kouchi, Akira NRID 1000060161866 en Watanabe, Naoki NRID 1000050271531
Accessrights	metadata only access
Subject	NDC 420
Description	Abstract en Phosphine (PH3) is an important molecule in the chemistry of phosphorus (P)-bearing species in the interstellar medium. Interstellar PH3 is thought to primarily form on icy grains, where several surface processes may occur during and after its formation. To better understand the physicochemical behavior of PH3 on icy grains in dense molecular clouds, we performed experimental and computational studies on the reactions of phosphine with H and D atoms at low temperatures. We found that phosphine and its deuterated isotopologue PD3 are released into the gas phase from icy surfaces (porous amorphous, compact amorphous, and crystalline ice) via chemical desorption. Even though the effective desorption cross section did not vary between the different icy surfaces, the desorption fraction was smallest for porous amorphous ice. We confirmed that, at 10 K on icy surfaces, H-D substitution reactions of PH3 and D-H substitution reactions of PD3 occurred following reactions with D and H atoms, respectively. Because the activation barrier for the abstraction of H or D atoms from phosphine is similar to 1500 K, quantum tunneling should play a role at low temperatures. Under the present experimental conditions, the H-D substitution reaction of PH3 was slightly slower than the D-H substitution reaction of PD3. Therefore, the rates of the H-D and D-H substitution reactions should not be constrained by tunneling reactions but rather by other elementary processes such as atom diffusion on ice. Our experimental results suggest the possible presence of a deuterated phosphine isotopologue (PH2D) in PH3-rich interstellar environments.
Publisher	en IOP Publishing
Date	Issued2021-09-09
Language	eng
Resource Type	journal article
Version Type	NA
Identifier	HDL http://hdl.handle.net/2115/86717
Relation	isIdenticalTo DOI https://doi.org/10.3847/1538-4357/ac0cf4
Journal	PISSN 0004-637X en Astrophysical journal Volume Number918 Issue Number2 Page Start73
Oaidate	2023-07-26