Abstract Details
High Intensity Femtosecond XUV Pulse Interactions with Atomic Clusters
Author: Kay Hoffmann
Requested Type: Oral Only
Submitted: 2009-04-21 16:38:22
Co-authors: B. Murphy, A. Helal, B. Erk, N. Kandadai, J. Keto, T. Ditmire
Contact Info:
The University of Texas at Austin
2511 Speedway Street, RLM 12.2
Austin, TX 78712
US
Abstract Text:
The nature of the interactions between high intensity, ultrafast, near infrared laser pulses and atomic clusters of a few hundred to a few hundred thousand atoms has been well studied over the past few years by a number of groups world wide. Such studies have found some rather unexpected results, including the striking finding that these interactions appear to be more energetic than interactions with either single atoms or solid density plasmas and that clusters explode with substantial energy when irradiated by an intense laser. We have extended these studies with intense IR lasers by examining interactions of intense extreme ultraviolet (XUV) pulses with atomic clusters.
Our studies with XUV light are designed to illuminate the mechanisms for intense pulse interactions in the regime of high intensity but low ponderomotive energy. This regime of interaction is very different from interactions of intense IR pulses with clusters where the laser ponderomotive potential is significantly greater than the binding potential of electrons in the cluster.
We have been conducting these studies by converting a high-energy (1 J) femtosecond laser to the short wavelength region through high order harmonic generation. These harmonics are focused to an intensity of up to 1011 W/cm2 into a cluster jet and the ion and electrons ejected are analyzed by time-of-flight methods. Our first experiments have been done on Xe clusters irradiated by intense femtosecond 32.6 eV pulses. We have observed surprising high charge states with a hydrodynamic based energy distribution from exploding Xe clusters. We surmise that continuum lowering in the created cluster nanoplasma makes single photo ionization of the cluster atoms to higher charge states possible [1].
These experiments look toward high intensity cluster interaction experiments on the Linac Coherent Light Source (LCLS) under development at SLAC. We plan to extend our measurements to the X-ray region and will provide charge state and energy distributions of exploding clusters as a model system for the first imaging experiments on non-crystalline biological macromolecules [2].
[1] B. Murphy et al, Phys. Rev. Lett. 101, 203401 (2008).
[2] R. Neutze et al, Nature 406, 752 (2000).
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