Ion yield spectroscopy of sodium following K-shell photoexcitation

Photoion yields of sodium have been measured following K-shell excitation by time-of-flight (TOF) technique with a high-resolution incident photon energy. For comparison, we also measured single- and double-excitation spectra for Ne in the K-shell excitation region. The incident energy dependence of Na ion TOF spectra shows that in the 1s single-excitation (1s-1np) region below the K-edge (1079 eV), the Na2+ yield is dominant and the fraction of Na+ is much smaller. This is very different when compared with the results of neon single-excitation. Above the K-edge, Na2+ yield decreases and Na3+ yield increases