GENERALIZED OSCILLATOR STRENGTHS IN ELECTRON IMPACT SPECTRA OF RUBIDIUM AND CAESIUM

Studies of generalized oscillator strengths as a function of incident electron kinetic energy within the range 33·5-100·5 eV have been made for rubidium and caesium using a crossed-beam high-resolution electron energy-loss spectrometer. Absolute generalized oscillator strengths have been derived by normalizing the resonance transition to the optical oscillator strength. For rubidium the reduced matrix elements (5 2Sparallelr2parallel6 2S) and (5 2Sparallelr2parallel7 2S) were found to be 44 A.U. ±25% and 15 A.U. ±40%, respectively, and the transition probabilities A(4 2D -> 5 2S) and A(5 2D -> 5 2S) found to be 204 s-1 ±10% and less than 24 s-1, respectively. For caesium the reduced matrix element (6 2Sparallelr2parallel7 2S) was found to be 57 A.U. ±20%, and the transition probabilities A(5 2D -> 6 2S), A(6 2D -> 6 2S) and A(7 2D -> 6 2S) were found to be 49 s-1 ±10%, 94 s -1 ±20% and 80 s-1 ±40%, respectively.