Phosphine Reactivity and Its Implications for Pyrolysis Experiments and Astrochemistry

Abstract

Despite the importance of phosphorus-bearing molecules for life and their abundance outside Earth, the chemistry of those compounds still is poorly described. The present study investigates phosphine (PH3) decomposition and formation pathways. The reactions studied include phosphine thermal dissociation, conversion into PO(2Π), PN(1Σ+), and reactions in the presence of H2O+. The thermodynamic and rate coefficients of all reactions are calculated in the range of 50–2000 K considering the CCSD(T)/6-311G(3df,3pd)//ωB97xD/6-311G(3df,3pd) electronic structure data. The rate coefficients were calculated by RRKM and semiclassical transition-state theory (SCTST). According to our results, PH3 is stable to thermal decomposition at T < 100 K and can be formed promptly by a reaction network involving PH(3Σ–), PO(2Π), and PN(1Σ+). In the presence of radiation or ions, PH3 is readily decomposed. For this reason, it should be mainly associated with dust grains or icy mantles to be observed under the physical conditions prevailing in the interstellar medium (ISM). The intersystem crossing associated with the dissociation of the isomers PON, NPO, and PNO is accessed by multireference methods, and its importance for the gas-phase PH3 formation/destruction is discussed. Also, the implications of the present outcomes on phosphorus astrochemistry are highlighted.

Unlock the Visible-Light Photocatalytic OWS by Surface Disorder-Engineered Bi-Based Composite Oxides through Phosphorization

“…With an increasing calcination temperature, extra peaks referring to the metal Bi are observed, as shown in Figure S2. This suggests that H 3 P decomposed from NaH 2 PO 2 has a strong reductive effect . When the calcination temperature exceeds 300 °C, BiO x on the surface of BYVO is reduced to Bi by H 3 P. To further exclude the possibility of P doping in R-BYVO, R-BYVO is annealed at 850 °C in an air atmosphere for 8 h. If P was doped in R-BYVO, peaks should shift, and any impure peaks would be detected after high-temperature annealing.…”

High-temperature spectra of the PNO molecule based on robust first-principles methods

“…4 In molecular clouds and star-forming regions, PO and PN are the main P-bearing species, 5–7 and the reaction of PO + N → PN + O has been identified in several astronomical phosphorus chemical networks in the last five years. 8–12 The reaction intermediate PNO is believed to be an important species to potentially exist in the ISM. 13 Therefore, the spectrum of PNO is valuable for the spectroscopic characterization and possible astronomical detection of PNO.…”