High-resolution inelastic scattering of electrons by sodium atoms at zero angle

Zero-angle energy-loss spectra in sodium are obtained for incident electron energies of 7 to 500 eV using an electron spectrometer and a modulated atom beam. Absolute generalised oscillator strengths for excitation to the 4²S, 3²D, 4²P, 5²S and 5²P states are given. Values of reduced matrix elements, optical oscillator strengths and quadrupole transition probabilities are deduced for S-S, S-P and S-D transitions respectively. Comparison is made with previous experimental work and existing theory.