Direct Measurement of Anharmonic Decay Channels of a Coherent Phonon
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Scientists have probed in detail how vibrations in an atomic lattice created by laser pulses release their energy. The results agree well with numerical predictions.
Lattice vibrations in solids affect a wide range of phenomena, including the solid’s thermal, acoustic and electric properties. Vibrations triggered by laser pulses decay by dissipating their energy through the atomic lattice. While theoretical calculations have indicated that each vibration excites smaller vibrations that have higher frequencies, these had not been observed experimentally, until now.
By firing bright, ultrafast X-ray pulses directly after exciting lattice vibrations in a bismuth thin film using optical laser pulses, a team that included researchers at University College Cork has experimentally shown that the vibrations pass on their energy by triggering smaller vibrations.
The results will be helpful for informing analysis of a wide range of phenomena from heat flow in solids to light-induced superconductivity.
- Physical Review Letters 121, 125901 (2018). doi: 10.1103/PhysRevLett.121.125901