Zero-kinetic-energy photoelectron spectroscopy of Ar(2p)-excited argon clusters

Auger electron spectroscopy of free argon clusters

“…The spectral shape is found to be unchanged, within the given resolution of the CMA, as the average cluster size is increased. This is in agreement with the results of photoelectron and Auger spectroscopy of condensed and clustered argon, where small shifts relative to the atomic value are found for the Ar(2p) ionization energies (17). For solid argon the Auger lines broaden, but do not shift (18).…”

“…3 5 eV are observed for surface excitons, whereas bulk core excitons are blue-shifted by = l eV, as observed for the solid (20). For large clusters (N=530) the maximum of the lowest exciton state at 244.8 eV shows a shift which is typical for surface excitons, contrary to total electron yield and ZEKE yields recorded under identical expansion conditions where the contribution of bulk excitons dominates (4,17). We point out that total electron yield spectra, as well as ZEKE yield spectra, do not reflect the actual surface-to-bulk ratio of the neutral cluster size distribution since both techniques are particularly sensitive to those electrons which have low kinetic energy.…”

“…Another characteristic difference to TEY and ZEKE spectra concerns weak EXAFS oscillations in the Ar(2p) continuum, where the first pronounced maximum is observed at 256 eV (4,17). This finding points also to the surface sensitivity of the Auger electron yields, since surface bound atoms are expected to have less neighbors than argon atoms in the bulk of the cluster.…”

“…We observe, as in the case of TEY and ZEKE spectra for large cluster sizes a distinct resonance at 248 eV, corresponding to a blue-shift of 1 eV, which is typical for bulk excitons. Interestingly, the intensity of this feature is weaker for Auger yields, as compared to TEY and ZEKE spectra (4,17). which is another indication for the surface sensitivity of Auger yields.…”

2s-Excitation and Photoionization of Neon Clusters

“…Cations and electrons are detected alternatively by either a time-of-flight mass spectrometer (cf. [26]) or a threshold photoelectron spectrometer, which relies on angular discrimination of energetic electrons [27]. The experiments are performed in the multi-bunch mode of the storage ring.…”