Mainz 2017 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 14: Theory of Coupled Systems
MO 14.4: Vortrag
Donnerstag, 9. März 2017, 11:45–12:00, N 25
Sub-picosecond Energy Transfer Mechanism with Highly Intense and Ultrshort THz Pulses — •Pankaj Kumar Mishra1,2 and Robin Santra1,2,3 — 1Centre for Free Electron Laser Science, DESY, Hamburg, Germany — 2The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Germany — 3Department of Physics, University of Hamburg, Germany
With the advent of femtosecond lasers a couple of decades ago, ultrafast Temperature-jump experiments became possible and have since been used to study the very fast kinetics of fundamental steps in chemical reactions, folding processes in proteins and other biomolecules. Interestingly, T-jump experiments are also being used to study the fundamental aspects of the hydrogen bond dynamics and energy transfer in liquid water and other liquids in ultrashort timescales. We computationally investigated that one and half cycle, 141 fs long (fwhm) THz pulses spectrally centered at about 100 cm-1 (3 THz) can transfer the large amount of energy to the liquid water, generating a t-jump of 700~k within less than a ps time-scale. Here, I will talk about the dynamics of ultrafast energy transfer from water clusters to bulk water by such THz pulses. I will present the mechanisms by which rotational and translational degrees of freedom of the water monomers gain energy from these sub-cycle pulses and discuss the ultrafast H-bond modification. Through their permanent dipole moment, water molecules are acted upon by the electric field and forced off their preferred H-bond network conformation.