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

Phosphine (PH3) is an important molecule in the chemistry of phosphorus (P)-bearing species interstellar medium. Interstellar PH3 thought to primarily form on icy grains, where several surface processes may occur during and after its formation. To better understand physicochemical behavior grains dense molecular clouds, we performed experimental computational studies reactions phosphine with H D atoms at low temperatures. We found that deuterated isotopologue PD3 are released into gas phase from surfaces (porous amorphous, compact crystalline ice) via chemical desorption. Even though effective desorption cross section did not vary between different surfaces, fraction was smallest for porous amorphous ice. confirmed that, 10 K H–D substitution D–H occurred following atoms, respectively. Because activation barrier abstraction or ∼1500 K, quantum tunneling should play a role Under present conditions, reaction slightly slower than PD3. Therefore, rates be constrained by but rather other elementary such as atom diffusion Our results suggest possible presence (PH2D) PH3-rich environments.