Vacuum ultraviolet photochemistry of sulfuric acid vapor: a combined experimental and theoretical study

Cuihong Zhang , Xiaoxiao Lin , Xiaofeng Tang , Christa Fittschen (1) , Sebastian Hartweg (2) , Gustavo A Garcia (2) , Bo Long , Weijun Zhang , Laurent Nahon (2)

1 PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522
2 SSOLEIL - Synchrotron SOLEIL

We present a vacuum ultraviolet (VUV) photoionization study of the gas-phase sulfuric acid (H2SO4) molecule in the 11–14 eV energy range by using the method of synchrotron radiation-based double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy complemented with accurate theoretical calculations. The slow photoelectron spectrum (SPES) of H2SO4 has been acquired and the three electronic states of H2SO4+, X2A, A2A and B2A have been populated and assigned. The adiabatic ionization energy of the H2SO4 molecule towards the X2A cationic ground state is measured at 11.684 ± 0.006 eV, in accordance with high-level calculated findings. With increasing photon energies, the H2SO4+ cation dissociates into HSO3+ and OH fragments and their adiabatic appearance energy is measured at 13.498 ± 0.007 eV. Then, the enthalpies of formation for the species involved in the photoionization and dissociative photoionization have been determined through a thermochemical cycle.

Domaines: Chimie

Cuihong Zhang, Xiaoxiao Lin, Xiaofeng Tang, Christa Fittschen, Sebastian Hartweg, et al.. Vacuum ultraviolet photochemistry of sulfuric acid vapor: a combined experimental and theoretical study. Physical Chemistry Chemical Physics, 2022, 24 (4), pp.2015-2021. ⟨10.1039/D1CP05237C⟩. ⟨hal-03872639v2⟩