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Univ. Paris-Saclay
Dynamics of Clusters and Nanoparticles
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Low field laser ionization of argon clusters: The remarkable fragmentation dynamics of doubly ionized clusters

L. Poisson, K. D. Raffael, M. A. Gaveau, B. Soep, J. M. Mestdagh, J. Caillat, R. Taieb and A. Maquet

Phys. Rev. Lett., 99, 103401, 2007 [doi]

We have investigated the fission following a Coulomb explosion in argon clusters (up to Ar800) irradiated by a femtosecond infrared laser with moderate intensity IL≈10^13  W cm−2. We report the a priori surprising observation of well-defined velocity distributions of the ionized fragments Ar+n<50. This is interpreted by the formation of a valence shell excited charged ion, followed by relaxation, charge transfer by autoionizing collision at very short distance, and asymmetric fission


Self-Trapping Relaxation Decay Investigated by Time-Resolved Photoelectron Spectroscopy

A. Lietard, G. Piani, M. Briant, M.-A. Gaveau, S. Faisan, V. Mazet, B. Soep, J.-M. Mestdagh and L. Poisson

Phys. Chem. Chem. Phys., 20, 11206, 2018 [doi]

The present work combines time-resolved photoelectron spectroscopy on isolated species with high-level data processing to address an issue which usually pertains to materials science: the electronic relaxation dynamics towards the formation of a self-trapped exciton (STE). Such excitons are common excited states in ionic crystals, silica and rare gas matrices. They are associated with a strong local deformation of the matrix. Argon clusters were taken as a model. They are excited initially to a Wannier exciton at 14 eV and their evolution towards the formation of an STE has showed an unusual type of vibronic relaxation where the electronic excitation of the cluster decreases linearly as a function of time with a 0.59 ± 0.06 eV ps−1 rate. The decay was followed for 3.0 ps, and the STE formation occurred in ∼5.1 ± 0.7 ps.

#2939 - Màj : 05/09/2018


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