A new method for determining f-values using stimulated electronic Raman scattering in atomic vapours

Abstract

After introducing relations linking intensities of spectral lines and oscillator strengths of electric dipole transitions the difficulties of f-value measurements in the near infrared are considered. A new technique is described based on the measurement of the polarisation of infrared radiation generated by stimulated electronic Raman scattering in atomic vapours. Results obtained in caesium are compared with theoretical values for radial matrix element ratios. It is concluded that the anomalous intensity ratios observed in the principal series doublets of caesium can be predicted accurately only by theoretical calculations which include the effects of core polarisation and the correct relativistic spin-orbit interaction. The experimental result for the ratio of the absorption f-values of the previously inaccessible transitions 7s2S1/2-7p2P3/2,1/2 at 2.931 mu m and 3.095 mu m respectively is 4.12+or-0.66. Extensions of these nonlinear optical techniques to magnetic dipole and electric quadrupole transitions are noted.