Eur. Phys. J. D 20, 261-268 (2002)
https://doi.org/10.1140/epjd/e2002-00136-9

Photoexcitation of rare-gas neon and argon clusters doped with H₂O

¹ Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions, CNRS, Institut Galilée, université Paris-Nord, 93430 Villetaneuse, France
² Laboratoire Physique des Lasers, CNRS, Institut Galilée, université Paris-Nord, 93430 Villetaneuse, France
³ Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronen Synchrotron DESY, Hamburg, Notkestr. 85, 22603 Hamburg, Germany

Corresponding author: ^a kanaev@limhp.univ-paris13.fr

Received: 7 March 2002
Revised: 27 May 2002
Published online: 19 July 2002

Abstract

We have studied the fluorescence of electronically excited OH^*, H^* and H₂O^+* dissociation fragments after VUV excitation () of rare-gas clusters (Rg = Ne, Ar) doped with H₂O molecules. In contrast to a free molecule, where Balmer H-series dominate the UV-visible spectra, only the OH) emission band is observed in neon clusters. No emission of excited water ions has been observed. We find that while higher excitation energies (Ne vs. Ar) induce higher vibrational excitation of the OH^* (A) fragment, the rotational temperature is lower. This effect is attributed to the difference in the geometric position of the H₂O molecule on the surface or inside the Rg-cluster. The rotational relaxation in neon clusters is rapid while the vibrational relaxation is slow because of the coupling with the low energy matrix phonons.