Jun 25 – 27, 2018
Stockholm, Alba Nova
Europe/Stockholm timezone

Coherent X-rays reveal the influence of cage effects on ultrafast water dynamics

Jun 26, 2018, 9:30 AM
30m
Oskar Klein Auditorium (Stockholm, Alba Nova)

Oskar Klein Auditorium

Stockholm, Alba Nova

Stockholm University
Invited oral Imaging and scattering

Speaker

Fivos Perakis (Stockholm University)

Description

The dynamics of liquid water feature a variety of time scales, ranging from extremely fast ballistic-like thermal motion, to slower molecular diffusion and hydrogen-bond rearrangements. Here, will be presented our recent studies[1] using ultrafast coherent X-ray diffraction to investigate the sub-100fs dynamics of water from ambient conditions down to supercooled temperatures. This novel approach utilizes the inherent capability of X-ray speckle visibility spectroscopy at LCLS to measure equilibrium intermolecular dynamics with lengthscale selectivity, by measuring oxygen motion in momentum space.

The observed decay of the speckle contrast at the first diffraction peak, which reflects tetrahedral coordination, is attributed to motion on a molecular scale within the first 120 fs. Through comparison with molecular dynamics simulations, we conclude that the slowing down upon cooling from 328 K down to 253 K is not due to simple thermal ballistic-like motion, but that cage effects play an important role even on timescales over 25 fs due to hydrogen-bonding.

[1] F. Perakis et al., “Coherent X-rays reveal the influence of cage effects on ultrafast water dynamics,” Nat. Commun., vol. 9, no. 1, p. 1917, (2018).

Primary authors

Fivos Perakis (Stockholm University) Gaia Camisasca (Stockholm University) Thomas J. Lane (SLAC National Accelerator Laboratory) Alexander Späh (Stockholm University) Kjartan Thor Wikfeldt (Stockholm University) Jonas A. Selberg (KTH Royal Institute of Technology) Felix Lehmkühler (Deutsches Elektronen-Synchrotron DESY) Harshad Pathak (Stockholm University) Kyung Hwan Kim (Stockholm University) Katrin Amann-Winkel (Stockholm University) Simon Schreck (Stockholm University) Sanghoon Song (SLAC National Accelerator Laboratory) Takahiro Sato (SLAC National Accelerator Laboratory) Marcin Sikorski (European XFEL) Andre Eilert (SLAC National Accelerator Laboratory) Wojciech Roseker (Deutsches Elektronen-Synchrotron DESY) Aymeric Robert (SLAC National Accelerator Laboratory) Gerhard Grübel (Deutsches Elektronen-Synchrotron DESY) Lars G. M. Pettersson (Stockholm University) Anders Nilsson (Stockholm University)

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