Issue |
Europhys. Lett.
Volume 61, Number 6, March 2003
|
|
---|---|---|
Page(s) | 762 - 768 | |
Section | Condensed matter: structure, mechanical and thermal properties | |
DOI | https://doi.org/10.1209/epl/i2003-00299-3 | |
Published online | 01 March 2003 |
Time-resolved X-ray diffraction on laser-excited metal nanoparticles
1
ESRF - BP 220, F-38043 Grenoble, France
2
Fachbereich Physik der Martin-Luther-Universität Halle-Wittenberg Friedemann-Bach-Platz 6, D-06108 Halle, Germany
3
ESPCI - 10 rue Vauquelin, F-75005 Paris, France
4
Physics Department and CeNS, University of Munich Amalienstrasse 54, D-80799 München, Germany
5
I. Physikalisches Institut, RWTH Aachen - D-52056 Aachen, Germany
Received:
9
August
2002
Accepted:
3
January
2003
The lattice expansion and relaxation of noble-metal nanoparticles
heated by intense femtosecond laser pulses are measured by
pump-probe time-resolved X-ray scattering. Following the laser
pulse, shape and angular shift of the (111) Bragg reflection from
crystalline silver and gold particles with diameters from 20 to
100 are resolved stroboscopically using 100
X-ray
pulses from a synchrotron. We observe a transient lattice
expansion that corresponds to a laser-induced temperature rise of
up to 200
, and a subsequent lattice relaxation. The
relaxation occurs within several hundred picoseconds for
embedded silver particles, and several nanoseconds for supported
free gold particles. The relaxation time shows a strong
dependence on particle size. The relaxation rate appears to be
limited by the thermal coupling of the particles to the matrix
and substrate, respectively, rather than by bulk thermal
diffusion. Furthermore, X-ray diffraction can resolve the
internal strain state of the nanoparticles to separate
non-thermal from thermal motion of the lattice.
PACS: 61.10.Nz – Single-crystal and powder diffraction / 65.80.+n – Thermal properties of small particles, nanocrystals, nanotubes / 78.47.+p – Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter
© EDP Sciences, 2003
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