Quantitative photoabsorption and fluorescence study of H2O and D2O at 50-190 nm

Cross sections and oscillator strengths for electron-impact excitation of the ÃB11 electronic state of water

“…20,[35][36][37][38][39] The present OOS value of f = 0.0459± 0.0069 is in excellent agreement with the photoabsorption results from Lee and Suto 42 and Yoshino et al, 43,44 and the f sum-rule adjusted value recommended by Berkowitz,58 and in good accord with the highresolution dipole ͑e , e͒ value from Chan et al 32 We therefore believe that the OOS for the à 1 B 1 excitation of H 2 O is well established. This is important as the OOS represents a good test 62 for any structure calculation seeking to accurately represent the wave functions for this excitation.…”

“…The experimental OOS for the à 1 B 1 excitation, as derived using the above procedure, is given in Table IV along with a comparison of some of the results from previous experiments 32, [40][41][42][43][44]58 and calculations. 20,[35][36][37][38][39] The present OOS value of f = 0.0459± 0.0069 is in excellent agreement with the photoabsorption results from Lee and Suto 42 and Yoshino et al, 43,44 and the f sum-rule adjusted value recommended by Berkowitz,58 and in good accord with the highresolution dipole ͑e , e͒ value from Chan et al 32 We therefore believe that the OOS for the à 1 B 1 excitation of H 2 O is well established.…”

“…6 In both the molecular spectroscopy case and for the scattering calculations, an important first test to verify the quality of target wave functions is to compare the length and velocity forms of calculated oscillator strengths to corresponding accurate experimental values. For the optical oscillator strength ͑OOS͒ for excitation of the à 1 B 1 electronic state from the X 1 A 1 ground state, there are theoretical 20,[35][36][37][38][39] and experimental 32,[40][41][42][43][44] data available in the literature. In general we find differences in the OOS values within the theories and within the experiments and between the existing theories and experiments.…”

Molecular investigations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught) at small heliocentric distances

“…We studied the screening of photolysis using simplified assumptions: isotropic outgassing at a constant expansion velocity and an infinite lifetime for the screening molecules (i.e., we assumed that their scale length is larger than the size of the optically thick region). According to Nee & Lee (1985), when considering Lee & Suto (1986) and Lee (1984), the OH photoabsorption cross-section does not differ much from the H 2 O one: it peaks close to the Lyman α wavelength and is slightly stronger (1-2 times). On the other hand, the cometary hydrogen may not absorb significantly the Solar Lyman α spectral line.…”

“…where most of the contribution comes from Lyman α (σ H 2 O (Ly α) = 15 × 10 −22 m 2 , Lee & Suto 1986;Lewis et al 1983). This approximation was validated by ourselves for HCN: we estimated numerically that using this mean value for the screening cross-section instead of summing over various wavelength intervals yields only a ≈2% excess error in the estimate of the increase in the number of molecules due to screening.…”