OH(A2-SIGMA+-]X2-PI-I) YIELD FROM H2O PHOTO-DISSOCIATION IN 1050-1370 A

The cross section and the quantum yield for the production of the OH(A 2Σ+→X2Πi) 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 3α 1→4α1 valence transition and the 3α1→3sα1 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 H 2O in the current wavelength region are discussed. © 1980 American Institute of Physics.