Berlin 2014 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 4: Theory 1: Molecular Dynamics
MO 4.7: Vortrag
Montag, 17. März 2014, 15:45–16:00, BEBEL SR144
Ultrafast Energy Transfer by Short and Intense THz Pulse — •Pankaj Kumar Mishra1,2,3, Oriol Vendrell1,3, and Robin Santra1,2,3 — 1Center for Free-Electron Laser Science, DESY, Hamburg, Germany — 2Department of Physics, University of Hamburg, Hamburg, Germany — 3Center for Ultrafast Imaging,University of Hamburg, Hamburg, Germany
Liquid water is the single most important medium in which chemical and biological processes take place. The possibility to generate sub-ps and very intense THz pulses at free-electron lasers in full synchronization with the X-rays (XFEL) opens the possibility to time-resolved investigations of transient state of water and of molecular species dissolved in it.
Here, we investigated the response of liquid water to one-cycle, 200fs long THz pulses spectrally centered at about 100/cm−1 (∼3 THz). At an intensity of about 10E10 W/cm2, the pulse transfers energy mostly to translational mode of the water monomers along the polarization axis of the electric field. In a time-scale of 500fs to 1ps the energy redistributes to hindered rotational modes first, and to intramolecular vibrations last. We also investigated the response of Phenol molecule to such THz pulse in vapor phase and in liquid water environment. This study implies that the energy supplied by the THz can potentially activate chemical processes long before the large amount of energy supplied leads to volume increase and vaporization of the medium. In this study, we have used CP2K package for Ab-Initio Molecular Dynamics.