Structural relaxation in the hydrogen-bonding liquids n-methylacetamide and water studied by optical kerr effect spectroscopy

D.A. Turton, K. Wynne

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Structural relaxation in the peptide model N-methylacetamide (NMA) is studied experimentally by ultrafast optical Kerr effect spectroscopy over the normal-liquid temperature range and compared to the relaxation measured in water at room temperature. It is seen that in both hydrogen-bonding liquids, beta relaxation is present, and in each case, it is found that this can be described by the Cole-Cole function. For NMA in this temperature range, the alpha and beta relaxations are each found to have an Arrhenius temperature dependence with indistinguishable activation energies. It is known that the variations on the Debye function, including the Cole-Cole function, are unphysical, and we introduce two general modifications: One allows for the initial rise of the function, determined by the librational frequencies, and the second allows the function to be terminated in the alpha relaxation. (c) 2008 American Institute of Physics.
Original languageEnglish
Pages (from-to)154516
JournalJournal of Chemical Physics
Volume128
Issue number15
DOIs
Publication statusPublished - 21 Apr 2008

Keywords

  • mode-coupling theory
  • low-frequency modes
  • dielectric-relaxation
  • raman-spectroscopy
  • intermolecular dynamics
  • supercooled liquids
  • molecular liquids
  • light-scattering
  • ionic liquids
  • glass-formers
  • hydrogen bonds
  • librational states
  • liquid structure
  • optical Kerr effect

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