Generalized oscillator strengths for 7.4 eV excitation of H2O at 300, 400, and 500 eV kinetic energy. Singlet-triplet energy differences

Generalized oscillator strengths f have been determined as a function of scattering angle for the 7.4 eV excitation of H2O vapor by studying the scattering of electrons with kinetic energies of 300, 400, and 500 eV. Over the angle range studied, 2°–7°, f vs (ΔP)2 (ΔP the momentum change) lie approximately on a common curve at all three kinetic energies. Extrapolation to zero momentum change gives the value f0 =0.060±0.006 for the limiting oscillator strength. Singlet-triplet energy differences are calculated using the generalized oscillator strengths and a recently developed theory by Lassettre and Dillon.