Validity of Franck—Condon analysis procedures for deduction of excited-state and ionic geometries: Part II. The X2B1 and A2A1 states of hydrogen oxide and hydrogen sulphur

Abstract

The vibrational intensity distributions observed in the first two photoelectron bands of H 2O, D 2O and H 2S were adopted in studying the validity and limitations of different methods for carrying out Franck—Condon analyses. These methods include the generating function method, Coon et al.'s method, the Duschinsky matrix method and the two approximate methods involving the use of the vibrational quantum number with the maximum intensity as well as vertical and adiabatic ionization potentials within a progression. The geometries thus deduced for the H 2O + and H 2S + ions in the X 2 B 1 and A 2 A 1 states are in good agreement with observed values. Various criteria for the prediction of signs for changes in bond lengths and bond angles were discussed. Furthermore, the Badger's rule and the electrostatic force model were utilized to estimate quantitatively the changes in bond length on ionization.