Heterodyne x-ray diffuse scattering from coherent phonons

Here, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibriu...

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Bibliographic Details
Published in:Structural dynamics (Melville, N.Y.) N.Y.), 2017-09, Vol.4 (5), p.054305-054305
Main Authors: Kozina, M., Trigo, M., Chollet, M., Clark, J. N., Glownia, J. M., Gossard, A. C., Henighan, T., Jiang, M. P., Lu, H., Majumdar, A., Zhu, D., Reis, D. A.
Format: Article
Language:English
Subjects:
Acoustics
Amplitudes
Coherent scattering
Elastic scattering
Fourier transforms
Inelastic scattering
Materials analysis
MATERIALS SCIENCE
Nanoparticles
Newtonian mechanics
Phonons
Semiconductors
Symmetry
Temperature effects
X-ray scattering
X-rays
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Summary:Here, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons from the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.
ISSN:2329-7778
2329-7778
DOI:10.1063/1.4989401