Optical Oscillator Strengths for 3²S → 4²P and 3²S → 5²P Excitations of Na

The electron-energy-loss-spectrum of sodium has been measured in discrete region at a 1.5 keV impact energy and a mean scattering angle of 0°. The relative optical oscillator strength density spectrum of the valence shell of sodium was established by using the dipole (e, e) method and then normalized to the theoretical optical oscillator strength of the 3²s + 3²P excitation. The optical oscillator strengths of the 3²S → 4²P and 3²S → 5²P excitations obtained in the present work are 0.014 ± 0.002 and 0.0026 ± 0.0004, respectively. Theoretical values of optical oscillator strengths for 3²S → n²P (n = 3 - 5 ) excitations of sodium were obtained by using the relativistic configuration interaction method, which are 0.97, 0.012, and 0.0025, respectively.