Clusters in intense XUV pulses: Effects of cluster size on expansion dynamics and ionization

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.063201· OSTI ID:21550123

Ackad, Edward; Bigaouette, Nicolas; Briggs, Kyle; Ramunno, Lora ^[1]

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1. Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada)

We examine the effect of cluster size on the interaction of Ar{sub 55}-Ar{sub 2057} with intense extreme ultraviolet (XUV) pulses, using a model we developed earlier that includes ionization via collisional excitation as an intermediate step. We find that the dynamics of these irradiated clusters is dominated by collisions. Larger clusters are more highly collisional, produce higher charge states, and do so more rapidly than smaller clusters. Higher charge states produced via collisions are found to reduce the overall photon absorption, since charge states of Ar{sup 2+} and higher are no longer photoaccessible. We call this mechanism collisionally reduced photoabsorption, and it decreases the effective cluster photoabsorption cross section by more than 30% for Ar{sub 55} and 45% for Ar{sub 2057}. The time evolution of the electron kinetic energy distribution begins as a (mostly) Maxwellian distribution. Further, the electron velocity distribution of large clusters quickly become isotropic while smaller clusters retain the inherent anisotropy created by photoionization. Last, the total electron kinetic-energy distribution is integrated over the spatial profile of the laser and the log-normal distribution of cluster size for comparison with a recent experiment [C. Bostedt et al., Phys. Rev. Lett. 100, 133401 (2008)], and good agreement is found.

• OSTI ID: 21550123
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
ANISOTROPY
ARGON IONS
ATOMIC CLUSTERS
BOSONS
CHARGE STATES
CHARGED PARTICLES
COLLISIONS
CROSS SECTIONS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXTREME ULTRAVIOLET RADIATION
FERMIONS
IONIZATION
IONS
KINETIC ENERGY
LEPTONS
MASSLESS PARTICLES
PHOTOIONIZATION
PHOTONS
PULSES
RADIATIONS
SORPTION
TIME DEPENDENCE
ULTRAVIOLET RADIATION