Photoelectron Photoion Coincidence Measurements of Selenium Cluster Beam. II. Photon Energy Dependence : Atoms and Molecules

概要

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The photon energy dependence of the photoelectron photoion coincidence (PEPICO) spectra near the Se K-edge have been measured for Se_2 and larger species such as Se_5 at the BL-12C in Photon Factory. The PEPICO spectra reveal that the multiply charged ions, Se^<z+> are produced as a result of the de-excitation process following the inner-shell excitation. Two prominent structures corresponding to the π^*and σ^* resonances are clearly observed in the energy dependence of the branching ratio from Se_2, while only one structure corresponding to the σ^* resonance can be seen for the larger species. At the a resonance, the production of Se^+ and Se^<2+> is enhanced, in comparison with the direct ionization where the core-hole states are completely relaxed before the dissociation. The energies of the π^* and σ^* resonance relative to the is ionization potential are estimated at -10.0 ± 0.5 eV and -5 ± 1 eV, respectively. In addition, we propose a new method for the size-selective structural analysis of clusters by utilizing the PEPICO measurements.
社団法人日本物理学会の論文
2000-09-15