OH(<i>A</i> 2Σ+→<i>X</i> 2Π<i>i</i>) yield from H2O photodissociation in 1050–1370 Å

Abstract

The cross section and the quantum yield for the production of the OH(A 2Σ+→X 2Πi) emission from H2O photodissociation were measured, using synchrotron radiation in the 1050–1370 Å region. In the 1250–1370 Å region, the cross section for the OH emission has a vibrational structure different from the photoabsorption cross section, and the transitions responsible for the production of the OH emission are attributed to the 3a1→4a1 valence transition and the 3a1→3sa1 Rydberg transition. The quantum yields for the production of the OH emission appear weakly at 1366.5 Å and begin to increase sharply at 1362.5 Å. The quantum yields have a maximum value of 11% at 1300 Å and then decrease slowly with decreasing wavelengths. For wavelengths shorter than 1130 Å, the quantum yields vary sharply with photon energies. Various photodissociation processes of H2O in the current wavelength region are discussed.