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14 results on '"Harbst, M."'

5. Studies of resolidification of non-thermally molten InSb using time-resolved X-ray diffraction

Author

Harbst, M, Hansen, TN, Caleman, C, Fullagar, WK, Jonsson1, P, Sondhauss, P, Synnergren, O, Larsson, J, Harbst, M, Hansen, TN, Caleman, C, Fullagar, WK, Jonsson1, P, Sondhauss, P, Synnergren, O, and Larsson, J

Abstract

We have used time-resolved X-ray diffraction to monitor the resolidification process of molten InSb. Melting was induced by an ultra-short laser pulse and the measurement conducted in a high-repetition-rate multishot experiment. The method gives direct information about the nature of the transient regrowth and permanently damaged layers. It does not rely on models based on surface reflectivity or second harmonic generation (SHG). The measured resolidification process has been modeled with a 1-D thermodynamic heat-conduction model. Important parameters like sample temperature, melting depth and amorphous surface layer thickness come directly out of the data, while mosaicity of the sample and free carrier density can be quantified by comparing with models. Melt depths up to 80 nm have been observed and regrowth velocities in the range 2-8 m/s have been measured.

Published
2005

10. Time Resolved X-ray Diffraction and Non-Thermal Inelastic X-ray Scattering.

Author

Sondhauss, P., Harbst, M., Larsson, J., Naylor, G. A., Plech, A., Scheidt, K., Synnergren, O., Wark, J. S., Wulff, M., and Warwick, T.

Subjects
*X-ray diffraction, *PICOSECOND pulses, *RADIATION sources, *DETECTORS, *X-ray scattering, *PHONONS
Abstract

Atomic processes like e.g. molecular vibrations, chemical reactions or phase transitions happen on picosecond down to femtosecond time scales. Novel pulsed X-ray sources or alternatively ultrafast X-ray detectors allow the investigation of these processes in real time. A powerful tool for the investigation of the dynamics in crystalline materials is Time Resolved X-ray Diffraction (TRXD). As an example the authors present the measurement of “phonon branch folding” in a GaSb/InAs superlattice by means of TRXD. In the second part we look forward to the near future of TRXD. X-ray scattering from coherent acoustic and optical phonons has recently become describable within the framework of dynamical diffraction theory. This theory provides the means for the detailed modelling of how various lattice dynamical processes manifest themselves in the diffracted X-ray signal. Simulations are presented showing the effects of coherent acoustic and optical phonons on the rocking curve of quartz (010). © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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14. A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics.

Author

Fullagar W, Harbst M, Canton S, Uhlig J, Walczak M, Wahlström CG, and Sundström V

Abstract

A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic approximately 4-10 keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments.

Published
2007
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