Watching the Vibration and Cooling of Ultrathin Gold Nanotriangles by Ultrafast X-ray Diffraction - Université Claude Bernard Lyon 1 Access content directly
Journal Articles Journal of Physical Chemistry C Year : 2016

Watching the Vibration and Cooling of Ultrathin Gold Nanotriangles by Ultrafast X-ray Diffraction

Abstract

We study the vibrations of ultrathin gold nanotriangles upon optical excitation of the electron gas by ultrafast X-ray diffraction. We quantitatively measure the strain evolution in these highly asymmetric nano-objects, providing a direct estimation of the amplitude and phase of the excited vibrational motion. The maximal strain value is well reproduced by calculations addressing pump absorption by the nanotriangles and their resulting thermal expansion. The amplitude and phase of the out-of-plane vibration mode with 3.6 ps period dominating the observed oscillations are related to two distinct excitation mechanisms. Electronic and phonon pressures impose stresses with different time dependences. The nanosecond relaxation of the expansion yields a direct temperature sensing of the nano-object. The presence of a thin organic molecular layer at the nanotriangle/substrate interfaces drastically reduces the thermal conductance to the substrate.
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Dates and versions

hal-02289458 , version 1 (16-09-2019)

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A. von Reppert, R. M. Sarhan, F. Stete, J. Pudell, N. del Fatti, et al.. Watching the Vibration and Cooling of Ultrathin Gold Nanotriangles by Ultrafast X-ray Diffraction. Journal of Physical Chemistry C, 2016, 120, pp.28894-28899. ⟨10.1021/acs.jpcc.6b11651⟩. ⟨hal-02289458⟩
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