Δημοσιεύσεις

Project Acronym:
Title:
Affiliation: university of patras
Pi: Vlasis Mavrantzas
Research Field: chemical sciences and materials

Ultrafast rotational motions of supported nanoclusters probed by electron diffraction
by Vasileiadis, Thomas, Skountzos, Emmanuel N., Foster, Dawn, Coleman, Shawn P., Zahn, Daniela, Krečinić, Faruk, Mavrantzas, Vlasis G., Palmer, Richard E. and Ernstorfer, Ralph
Abstract:
In crystals, microscopic energy flow is governed by electronic and vibrational excitations. In nanoscale materials, however, translations and rotations of entire nanoparticles represent additional fundamental excitations. The observation of such motions is elusive as most ultrafast techniques are insensitive to motions of the phonons’ frame of reference. Here, we study heterostructures of size-selected Au nanoclusters with partial (111) orientation on few-layer graphite with femtosecond electron diffraction. We demonstrate that ultrafast, constrained rotations of nanoclusters, so-called librations, in photo-induced non-equilibrium conditions can be observed separately from vibrational structural dynamics. Molecular dynamics and electron diffraction simulations provide quantitative understanding on librations-induced deviations from the conventional temperature dependence of diffraction patterns. We find that nanocluster librations with a period of ∼20 picoseconds are triggered quasi-impulsively by graphene flexural motions. These ultrafast structural dynamics modulate the Au/C interface and hence are expected to play a key role in energy- and mass-transport at the nanoscale.
Reference:
Ultrafast rotational motions of supported nanoclusters probed by electron diffraction (Vasileiadis, Thomas, Skountzos, Emmanuel N., Foster, Dawn, Coleman, Shawn P., Zahn, Daniela, Krečinić, Faruk, Mavrantzas, Vlasis G., Palmer, Richard E. and Ernstorfer, Ralph), In Nanoscale Horiz., The Royal Society of Chemistry, 2019.
Bibtex Entry:
@article{C9NH00031C,
 author = {Vasileiadis, Thomas and Skountzos, Emmanuel N. and Foster, Dawn and Coleman, Shawn P. and Zahn, Daniela and Krečinić, Faruk and Mavrantzas, Vlasis G. and Palmer, Richard E. and Ernstorfer, Ralph},
 title = {Ultrafast rotational motions of supported nanoclusters probed by electron diffraction},
 journal = {Nanoscale Horiz.},
 year = {2019},
 bibyear = {2019},
 pages = {-},
 publisher = {The Royal Society of Chemistry},
 doi = {10.1039/C9NH00031C},
 url = {http://dx.doi.org/10.1039/C9NH00031C},
 abstract = {In crystals{,} microscopic energy flow is governed by electronic and vibrational excitations. In nanoscale materials{,} however{,} translations and rotations of entire nanoparticles represent additional fundamental excitations. The observation of such motions is elusive as most ultrafast techniques are insensitive to motions of the phonons’ frame of reference. Here{,} we study heterostructures of size-selected Au nanoclusters with partial (111) orientation on few-layer graphite with femtosecond electron diffraction. We demonstrate that ultrafast{,} constrained rotations of nanoclusters{,} so-called librations{,} in photo-induced non-equilibrium conditions can be observed separately from vibrational structural dynamics. Molecular dynamics and electron diffraction simulations provide quantitative understanding on librations-induced deviations from the conventional temperature dependence of diffraction patterns. We find that nanocluster librations with a period of ∼20 picoseconds are triggered quasi-impulsively by graphene flexural motions. These ultrafast structural dynamics modulate the Au/C interface and hence are expected to play a key role in energy- and mass-transport at the nanoscale.},
}