Progress on inner-shell excitations of molecular van der Waals clusters.
Recent progress on core-level excitation of molecular van der Waals clusters is reported. Resonant excitation near element K edges of isolated and clustered molecules gives rise to small spectral shifts that can only be detected with high spectral resolution. This requires the use of state-of-the-art storage-ring facilities along with insertion devices and high-resolution soft X-ray monochromators. Selected experimental results on carbon monoxide clusters are reported. For the vibrationally resolved C 1s --> pi* (v = 0) band of clustered CO, these indicate characteristic line broadening as well as a small red shift of 2 +/- 1 meV compared with the isolated molecule. The results are discussed within the framework of the quasi-atomic approach with respect to intermolecular interactions, freezing of molecular rotations in clusters, and dynamic localization of resonant core-to-valence excitations.
Rühl
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Fachbereich Physik, Universität Osnabrück, Germany. ruehl@uos.de
Flesch
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Tappe
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Pavlychev
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