Strong Anisotropy in Liquid Water upon Librational Excitation Using Terahertz Laser Fields

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Fabio Novelli - , Ruhr University Bochum (Author)
  • Luis Ruiz Pestana - , Lawrence Berkeley National Laboratory, University of California at Berkeley, University of Miami (Author)
  • Kochise C. Bennett - , Lawrence Berkeley National Laboratory, University of California at Berkeley (Author)
  • Federico Sebastiani - , Ruhr University Bochum (Author)
  • Ellen M. Adams - , Ruhr University Bochum (Author)
  • Nikolas Stavrias - , Radboud University Nijmegen (Author)
  • Thorsten Ockelmann - , Ruhr University Bochum (Author)
  • Alejandro Colchero - , Ruhr University Bochum (Author)
  • Claudius Hoberg - , Ruhr University Bochum (Author)
  • Gerhard Schwaab - , Ruhr University Bochum (Author)
  • Teresa Head-Gordon - , Lawrence Berkeley National Laboratory, University of California at Berkeley (Author)
  • Martina Havenith - , Ruhr University Bochum (Author)

Abstract

Tracking the excitation of water molecules in the homogeneous liquid is challenging due to the ultrafast dissipation of rotational excitation energy through the hydrogen-bonded network. Here we demonstrate strong transient anisotropy of liquid water through librational excitation using single-color pump-probe experiments at 12.3 THz. We deduce a third-order response of χ3 exceeding previously reported values in the optical range by 3 orders of magnitude. Using a theory that replaces the nonlinear response with a material property amenable to molecular dynamics simulation, we show that the rotationally damped motion of water molecules in the librational band is resonantly driven at this frequency, which could explain the enhancement of the anisotropy in the liquid by the external terahertz field. By addition of salt (MgSO4), the hydration water is instead dominated by the local electric field of the ions, resulting in reduction of water molecules that can be dynamically perturbed by THz pulses.

Details

Original languageEnglish
Pages (from-to)4989-5001
Number of pages13
JournalJournal of Physical Chemistry B
Volume124
Issue number24
Publication statusPublished - 18 Jun 2020
Peer-reviewedYes
Externally publishedYes

External IDs

PubMed 32450043
ORCID /0000-0002-8120-8553/work/161409563