Femtosecond Vibrational Sum-Frequency Generation Spectroscopy of Chiral Molecules in Isotropic Liquid

Taegon Lee, Hanju Rhee, Minhaeng Cho

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Abstract

Vibrationally resonant optically active (VOA) sum-frequency generation (SFG) is a second-order nonlinear process sensitive to the stereospecific vibrational structure of chiral molecules. We demonstrate that a femtosecond VOA SFG signal can be measured in the isotropic bulk of a chiral liquid. The chiral, achiral, and VOA SFG spectra of R- and S-limonene and their racemic mixture in the C-H stretching frequency region are characterized. In particular, it is shown that the observed circular intensity difference (CID) signal, which can provide distinguishable stereochemical vibrational information between enantiomers, arises from interference of the electric-dipole allowed antisymmetric Raman tensor-induced and Raman optical activity (ROA) tensor-induced SFG fields. Furthermore, we show that the CID and linear polarization intensity difference (LID) SFG spectra are connected to the real and imaginary parts of the effective chiral VOA SFG susceptibility, respectively. We anticipate that the present technique will be of use in transient chiroptical spectroscopy and stereochemical vibrational imaging studies.

Original languageEnglish
Pages (from-to)6723-6730
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume9
Issue number23
DOIs
Publication statusPublished - 2018 Dec 6

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ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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