Eur. Phys. J. D 58, 131-136 (2010)
https://doi.org/10.1140/epjd/e2010-00055-2

Exploration of dynamical regimes of irradiated small protonated water clusters

¹ CEA Saclay, DEN/SRMP, 91191 Gif-sur-Yvette Cedex, France
² Laboratoire de Physique Théorique, IRSAMC, UPS and CNRS, Université de Toulouse, 118 route de Narbonne, 31062 Toulouse Cedex, France
³ Institut für Theoretische Physik, Universität Erlangen, Staudtstrasse 7, 91058 Erlangen, Germany
⁴ School of Science, JiangNan University, Wuxi, 214122, China

Corresponding author: dinh@irsamc.ups-tlse.fr

Received: 14 December 2009
Revised: 2 February 2010
Published online: 9 March 2010

Abstract

We explore from a theoretical perspective the dynamical response of small water clusters, (H₂O)_nH₃O⁺ with n=1,2,3, to a short laser pulse for various frequencies, from infrared (IR) to ultra-violet (UV) and intensities (from 6 × 1013 W/cm2 to 5 × 1014 W/cm2). To that end, we use time-dependent local-density approximation for the electrons, coupled to molecular dynamics for the atomic cores (TDLDA-MD). The local-density approximation is augmented by a self-interaction correction (SIC) to allow for a correct description of electron emission. For IR frequencies, we see a direct coupling of the laser field to the very light H⁺ ions in the clusters. Resonant coupling (in the UV) and/or higher intensities lead to fast ionization with subsequent Coulomb explosion. The stability against Coulomb pressure increases with system size. Excitation to lower ionization stages induced strong ionic vibrations. The latter maintain a rather harmonic pattern in spite of the sizeable amplitudes (often 10% of the bond length).