Formation of Phosphorus Monoxide (PO) in the Interstellar Medium: Insights from Quantum-chemical and Kinetic Calculations

In recent years, phosphorus monoxide (PO) -- an important molecule for prebiotic chemistry has been detected in star-forming regions and the comet 67P/Churyumov-Gerasimenko. These studies have revealed that, interstellar medium, PO is systematically most abundant P-bearing species, with abundances that are $\sim$1-3 times greater than those derived nitride (PN), second P-containing molecule. The reason why more PN remains still unclear. Experimental gas phase not available, probably because of difficulties dealing its compounds. Therefore, reactivity atomic needs to be investigated using reliable computational tools. To this end, state-of-the-art quantum-chemical computations employed evaluate accurate reaction rates branching ratios P + OH $\rightarrow$ H H$_2$O H$_2$ reactions framework a master equation approach based on ab-initio transition state theory. hypothesis H${_2}$O can potential oxidizing agents ubiquitous presence ISM. Its destruction then produces OH, which another very species. While gound water relevant source emerged energy barriers, represents formation route medium. Our kinetic results show follow Arrhenius behavior, thus rate coefficients alpha=2.28$\times$10$^{-10}$ cm${^3}$ molecule$^{-1}$ s$^{-1}$, beta=0.16 gamma=0.37 K increase by increasing temperature.