Optical Absorption of Solid Neon and Argon in the Soft X-Ray Region

Abstract

The absorption spectra of thin films of solid Ne and Ar have been measured in the photon energy range 25 to 500 eV. For comparison with the atomic states the corresponding spectra in the gas have also been investigated. The 7.5 GeV electron synchroton DESY served as light source. Near the onset of inner shell transitions (2 s in Ne, 3 s and 2 p in Ar) fine structure can be seen which is characteristic for the solid or atomic state. The structure in the spectra of the solid is ascribed to exciton and interband transitions. The absorption in the continuum at some distance from the various thresholds shows great similarities between the solid and gaseous states

Auger electron spectroscopy of free argon clusters

“…Small blue-shifts of 4 . 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).…”

“…This is especially true for the lowest Ar(2p),,+4s transition, since it is an isolated Frenkel-type exciton (20). Small blue-shifts of 4 .…”

Core level excitation of atomic and molecular clusters

“…It has been found that the shapes of inner shell absorption spectra of isolated atoms differ from those of the corresponding condensed species. 3 In contrast to this valence transitions of core excited molecular species (1s→π*) show typically the same energy positions in the gas and condensed phase. 4 However, intensity changes of discrete resonances relative to the corresponding ionization continua are observed.…”

“…Fig. 2b for a two body dissociation reaction (Ar 3 ++ →Ar + /Ar 2 + ). Various other charge separation reactions involving three body dissociations and evaporation of neutrals are discussed in ref.…”

“…This energy corresponds to 3d (3/2) exciton state in clusters and the solid. 3,6,7 Three series of charge separation product channels are identifed: Ar + /Ar n + , Ar 2 + /Ar n + and Ar 3 + /Ar n + . These series of charge separation show that asymmetric fission of argon cluster dications is dominant.…”