Energy band dispersion in photoemission spectra of argon clusters

• Using photoemission we have investigated free argon clusters from a supersonic nozzle expansion in the photon energy range from threshold up to 28 eV. Measurements were performed both at high resolution with a hemispherical electrostatic energy analyser and at lower resolution with a magnetic bottle device. The latter experiments were performed for various mean cluster sizes. In addition to the approximate to 15eV broad 3p-derived valence band seen in previous work, there is a sharper feature at approximate to 15eV binding energy. Surprisingly for non-oriented clusters, this peak shifts smoothly in binding energy over the narrow photon energy range 15.5-17.7 eV, indicating energy band dispersion. The onset of this bulk band-like behaviour could be determined from the cluster size dependence.

Nyckelord

Cluster

Band structure

Argon

Photoelecton spectroscopy

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