Quantitative photoabsorption and fluorescence study of H 2O and D 2O at 50-190 nm

Abstract

The photoabsorption cross sections and the fluorescence quantum yields of H 2O and D 2O were measured in the 50-190 nm region using synchrotron radiation as a light source. The oscillator streng4ths for the Rydberg states of H 2O and D 2O were determined from the absorption cross sections measured. The processes for the production of fluorescence from the excited species of H*( n > 2), D*( n > 2), OH*(A) and OD*(A)are discussed. The upper limit for the dissociation energy of D(D-OD) was determined, from the threshold of the OD(A-X) fluorescence,to be 5.14±0.01 eV. The upper limit for the cross section of visible fluorescence from the excited H 2O + ions was determined to be 2x10 -19 cm 2. A comparison between the photoexcitation spectra of H 2O and D 2O is made.