Translational, rotational and vibrational relaxation dynamics of a solute molecule in a non-interacting solvent

Michael P. Grubb, Philip M. Coulter, Hugo J. B. Marroux, Balazs Hornung, Ryan S. McMullen, Andrew J. Orr-Ewing, Michael N.R. Ashfold

Research output: Contribution to journalArticle (Academic Journal)

9 Citations (Scopus)
321 Downloads (Pure)

Abstract

Spectroscopically observing the translational and rotational motion of solute molecules in liquid solutions is typically impeded by their interactions with the solvent, which conceal spectral detail through linewidth broadening. Here we show that unique insights into solute dynamics can be made with perfluorinated solvents, which interact weakly with solutes and provide a simplified liquid environment that helps to bridge the gap in our understanding of gas- and liquid-phase dynamics. Specifically, we show that in such solvents, the translational and rotational cooling of an energetic CN radical can be observed directly using ultrafast transient absorption spectroscopy. We observe that translational-energy dissipation within these liquids can be modelled through a series of classic collisions, whereas classically simulated rotational-energy dissipation is shown to be distinctly faster than experimentally measured. We also observe the onset of rotational hindering from nearby solvent molecules, which arises as the average rotational energy of the solute falls below the effective barrier to rotation induced by the solvent.
Original languageEnglish
Pages (from-to)1042-1046
Number of pages5
JournalNature Chemistry
Volume8
Issue number11
Early online date18 Jul 2016
DOIs
Publication statusPublished - Nov 2016

Keywords

  • Chemical physics
  • Reaction kinetics and dynamics
  • Optical spectroscopy

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