GENERALIZED OSCILLATOR STRENGTHS IN ELECTRON IMPACT SPECTRA OF POTASSIUM AND SODIUM

The results obtained in a previous paper for generalized oscillator strengths in potassium vapour have been re-examined. The angular resolution of the crossed-beam electron spectrometer used for the measurements has been improved and a correction applied for the residual finite angular resolution of the instrument. In addition to potassium, electron energy loss spectra for sodium at 40·5, 50·5, 67·5 and 100·5 ev incident electron kinetic energies have been obtained. Absolute generalized oscillator strengths have been derived by normalizing the resonance transition to the optical oscillator strength. For potassium the reduced matrix element (4 2S∥r2∥5 2S) was found to be 43 A.U. ± 20%, and the transition probability A(3 2D -> 4 2S) found to be 310 s-1 ± 20%. For sodium the reduced matrix elements for the transitions 3 2S -> 4 2S, 5 2S and 6 2S were found to be 33 A.U. ± 15%, 12 A.U. ± 20% and 7·5 A.U. ± 20%, respectively, and the transition probability A(3 2D -> 3 2S) found to be 690 s-1 ± 10%.