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Issue 32, 2008
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Water photodissociation in free ice nanoparticles at 243 nm and 193 nm

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Abstract

The photolysis of (H2O)nnanoparticles of various mean sizes between 85 and 670 has been studied in a molecular beam experiment. At the dissociation wavelength 243 nm (5.10 eV), a two-photon absorption leads to H-atom production. The measured kinetic energy distributions of H-fragments exhibit a peak of slow fragments below 0.4 eV with maximum at approximately 0.05 eV, and a tail of faster fragments extending to 1.5 eV. The dependence on the cluster size suggests that the former fragments originate from the photodissociation of an H2O molecule in the cluster interior leading to the H-fragment caging and eventually generation of a hydronium H3O molecule. The photolysis of surface molecules yields the faster fragments. At 193 nm (6.42 eV) a single photon process leads to a small signal from molecules directly photolyzed on the cluster surface. The two photon processes at this wavelength may lead to cluster ionization competing with its photodissociation, as suggested by the lack of H-fragment signal increase. The experimental findings are complemented by theoretical calculations.

Graphical abstract: Water photodissociation in free ice nanoparticles at 243 nm and 193 nm

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Article information


Submitted
23 Apr 2008
Accepted
04 Jun 2008
First published
25 Jun 2008

Phys. Chem. Chem. Phys., 2008,10, 4835-4842
Article type
Paper

Water photodissociation in free ice nanoparticles at 243 nm and 193 nm

V. Poterya, M. Fárník, M. Ončák and P. Slavíček, Phys. Chem. Chem. Phys., 2008, 10, 4835
DOI: 10.1039/B806865H

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