Abstract
Split-pulse x-ray photon correlation spectroscopy using x-ray free-electron laser is a promising tool to probe atomic dynamics in liquid and soft-matter in picosecond time scale, which has been accessible only by spectroscopy. However, sample heating by x-ray beam is a major obstacle for this technique. Using molecular dynamics and the two-temperature model we examine the atomic level response of water to x-ray laser pulse at picosecond time scale and compare with observations from recent x-ray free-electron laser experiments. We investigate the effects of the heating due to x-ray laser pulses of different energies and the effects of the heat dissipation on the structure and dynamics of water through the atomic density correlation and the dynamic structure factor. Our results indicate, in agreement with experiment that in addition to the beam energy the time delay between the two pulses is a critical factor for obtaining reliable information on the atomic level dynamics of water.
Highlights
Understanding the atomic-scale structure and dynamics of liquid is of fundamental importance for controlling the transport properties of liquid
In x-ray scattering experiments, the contributions from the correlation between the oxygen atoms are more dominant due to the larger number of electrons in oxygen compared to hydrogen [10] and the measurements and analyses are based on the oxygen-oxygen (OO) pairs
The pair-distribution function (PDF) for OO, hydrogen-hydrogen (HH) and hydrogen-oxygen (HO) pairs, for a representative set of simulations of 2 and 12 μJ x-ray laser beam energy, which are the lowest and the highest energy used in this work are shown in Fig. S1 in the Supplemental Material [46]
Summary
Understanding the atomic-scale structure and dynamics of liquid is of fundamental importance for controlling the transport properties of liquid. Water—one of the fundamental liquids—exhibits various anomalous features [1,2] To understand their physical origin, the structure and dynamics of water have been studied using x-ray and neutron scattering [3,4,5,6,7,8,9,10], optical spectroscopy [11,12,13], and computer simulation [14,15,16]. Elastic x-ray and neutron scattering provide the pair-distribution function (PDF) of liquid by means of Fourier transform of the structure function (SF). Recent work on extracting information on the atomic dynamics through inelastic x-ray scattering (IXS) elucidated the dynamic correlations in water through the Van Hove function, G(r, t) [18]. With the IXS only the dynamics up to a few ps can be probed because of the limited energy resolution
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
