Photoelectron spectroscopy of the caesium halides using synchrotron radiation

Photoelectron spectra of the molecular caesium halides have been studied using synchrotron radiation. Features are associated with ionisation from the halogen valence p 6 shells and from the caesium 5p 6 and 4d 10 shells. Structure is largely consistent with ionisation from a classical ionic molecule. Ionisation from the Cs + 5p shell gives rise to fine structure, which is attributed to electron correlation involving 'electron transfer' from the adjacent halogen anion. A similar process accompanying ionisation from the Cs + 4d shell appears to prevent the 4f wavefunction collapse expected for the free Cs + ion. N 4.5 O 2.3 O 2.3 Auger structure is observed associated with the collapse of all 4d holes.