Seminars Archive
Time-Resolved X-ray Laser Induced Photoelectron Spectroscopy for Probing Materials Dynamics
Abstract
Monday, July 18, 2005, 11:00
Seminar Room
Sincrotrone Trieste, Basovizza
Time-Resolved X-ray Laser Induced Photoelectron Spectroscopy
for Probing Materials Dynamics
A.J. Nelson
(Lawrence Livermore National Laboratory, Livermore, CA 94551)
Abstract
Time-resolved x-ray photoelectron spectroscopy is used to probe the
non-steady-state evolution of the valence band electronic structure of
laser heated ultra-thin (50 nm) Cu. Single-shot x-ray laser induced time-of-flight
photoelectron spectroscopy with picosecond time resolution is used in conjunction
with optical measurements of the disassembly dynamics that have shown the
existence of a metastable liquid phase in fs-laser heated Cu foils persisting
4-5 ps. This metastable phase is created using a 527 nm wavelength 400
fs laser pulse containing 0.1 - 2.5 mJ laser energy focused in a large
500 x 700 m2 spot to induce isochoric heating of the Cu under conditions
of 0.07 - 1.8 x 1012 W cm-2 intensity. Valence band photoemission spectra
showing the changing occupancy of the Cu 3d level with heating are presented.
These are the first picosecond x-ray laser time-resolved photoemission
spectra of laser-heated ultra-thin Cu foil showing changes in electronic
structure. The ultrafast nature of this technique lends itself to true
single-state measurements of shocked and heated materials.
This work was performed under the auspices of the U.S. Dept. of Energy
by the University of California Lawrence Livermore National Laboratory
under Contract No. W-7405-Eng-48.