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Title: Photochemical processes in doped argon-neon core-shell clusters: The effect of cage size on the dissociation of molecular oxygen
Authors: Laarmann, Tim
Wabnitz, Hubertus
von Haeften, Klaus
Möller, Thomas
First Published: 2-Jan-2008
Publisher: American Institute of Physics
Citation: Journal of Chemical Physics, 128, (1), 4502.
Abstract: The caging effect of the host environment on photochemical reactions of molecular oxygen is investigated using monochromatic synchrotron radiation and spectrally resolved fluorescence. Oxygen doped clusters are formed by coexpansion of argon and oxygen, by pickup of molecular oxygen or by multiple pickup of argon and oxygen by neon clusters. Sequential pickup provides radially ordered core-shell structures in which a central oxygen molecule is surrounded by argon layers of variable thickness inside large neon clusters. Pure argon and core-shell argon-neon clusters excited with ~12 eV monochromatic synchrotron radiation show strong fluorescence in the vacuum ultraviolet (vuv) spectral range. When the clusters are doped with O2, fluorescence in the visible (vis) spectral range is observed and the vuv radiation is found to be quenched. Energy-resolved vis fluorescence spectra show the 2¹Σ+→1¹Σ+(ArO(¹S)→ArO(¹D)) transition from argon oxide as well as the vibrational progression Α'³Δu(ν'=0)→X³Σ-g(ν'') of O2 indicating that molecular oxygen dissociates and occasionally recombines depending on the experimental conditions. Both the emission from ArO and O2 as well the vuv quenching by oxygen are found to depend on the excitation energy, providing evidence that the energy transfer from the photoexcited cluster to the embedded oxygen proceeds via the O+2 ground state. The O+2 decays via dissociative recombination and either reacts with Ar resulting in electronically excited ArO or it recombines to O2 within the Ar cage. Variation of the Ar layer thickness in O2–Ar–Ne core-shell clusters shows that a stable cage is formed by two solvation layers.
DOI Link: 10.1063/1.2815798
ISSN: 1089-7690
Type: Article
Rights: The following article appeared in the Journal of Chemical Physics, 2008, 128 (1), 4502, and may be found at Doi: 10.1063/1.2815798. Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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