Extreme ionization of Xe clusters driven by ultraintense laser fields

Journal Article · Tue Aug 21 00:00:00 EDT 2007 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2762217· OSTI ID:21024119

Heidenreich, Andreas; Last, Isidore; Jortner, Joshua ^[1]

---

1. School of Chemistry, Tel-Aviv University, 69978 Tel-Aviv (Israel)

We applied theoretical models and molecular dynamics simulations to explore extreme multielectron ionization in Xe{sub n} clusters (n=2-2171, initial cluster radius R{sub 0}=2.16-31.0 A ring ) driven by ultraintense infrared Gaussian laser fields (peak intensity I{sub M}=10{sup 15}-10{sup 20} W cm{sup -2}, temporal pulse length {tau}=10-100 fs, and frequency {nu}=0.35 fs{sup -1}). Cluster compound ionization was described by three processes of inner ionization, nanoplasma formation, and outer ionization. Inner ionization gives rise to high ionization levels (with the formation of (Xe{sup q+}){sub n} with q=2-36), which are amenable to experimental observation. The cluster size and laser intensity dependence of the inner ionization levels are induced by a superposition of barrier suppression ionization (BSI) and electron impact ionization (EII). The BSI was induced by a composite field involving the laser field and an inner field of the ions and electrons, which manifests ignition enhancement and screening retardation effects. EII was treated using experimental cross sections, with a proper account of sequential impact ionization. At the highest intensities (I{sub M}=10{sup 18}-10{sup 20} W cm{sup -2}) inner ionization is dominated by BSI. At lower intensities (I{sub M}=10{sup 15}-10{sup 16} W cm{sup -2}), where the nanoplasma is persistent, the EII contribution to the inner ionization yield is substantial. It increases with increasing the cluster size, exerts a marked effect on the increase of the (Xe{sup q+}){sub n} ionization level, is most pronounced in the cluster center, and manifests a marked increase with increasing the pulse length (i.e., becoming the dominant ionization channel (56%) for Xe{sub 2171} at {tau}=100 fs). The EII yield and the ionization level enhancement decrease with increasing the laser intensity. The pulse length dependence of the EII yield at I{sub M}=10{sup 15}-10{sup 16} W cm{sup -2} establishes an ultraintense laser pulse length control mechanism of extreme ionization products.

• OSTI ID: 21024119
• Journal Information: Journal of Chemical Physics, Vol. 127, Issue 7; Other Information: DOI: 10.1063/1.2762217; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ATOMIC CLUSTERS
CONTROL SYSTEMS
CROSS SECTIONS
ELECTRON-MOLECULE COLLISIONS
ELECTRONS
INNER-SHELL IONIZATION
LASER RADIATION
MOLECULAR DYNAMICS METHOD
PHOTOIONIZATION
PHOTON-MOLECULE COLLISIONS
PLASMA PRODUCTION
PULSES
SIMULATION
XENON