Theoretical Studies on Reactions of OH with H2SO4…NH3Complex and NH2with H2SO4in the Presence of Water

Abstract

The OH + H2SO4…NH3, NH2 + H2SO4, and NH2 + H2SO4…H2O reactions have been theoretically investigated using high-accuracy quantum chemical methods and conventional transition state theory. The calculation results reveal that remarkable tunneling effects appear at 200 K in the OH + H2SO4…NH3 reaction, compared with obvious tunneling effects below 100 K in the OH + NH3 reaction. The calculated rate constants predict that the hydrogen atom of the free OH group in M1 (H2SO4…NH3) abstracted via OH can compete well with the H atom in H2SO4 abstracted by OH at 200–240 K. The reaction kinetic results also show that a single water molecule could play an important role in the NH2 + H2SO4…H2O reaction below 240 K. The present results provide new insights into the atmospheric oxidation of sulfuric acid, which could be of great use in understanding atmospheric nucleation processes. Additionally, the findings are tunneling effects enhanced by sulfuric acid, which may be wide applications in reaction kinetics of gas-phase reactions.