Knowledge Bank

The use of PFI-ZEKE photoelectron spectroscopy as a means of recording rotationally resolved photoelectron spectra is now widespread. However, almost all of the work in this area has used multiphoton excitation to reach the ionization thresholds, and has thus been limited to states of the ion at or just above the lowest ionization threshold. We have used single photon excitation with broadly tunable coherent $VUV1$ to study ionization thresholds more than 6eV above the lowest ionization threshold, and have shown that the PFI-ZEKE method is very general, and can be applied even to predissociating states of molecular $ions2$. Some of our recent work using this technique will be reviewed, in order to illustrate the power and general applicability of this new method for the study of ion spectroscopy.