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Observation and calculation of vibrational circular birefringence: A new form of vibrational optical activity
Author(s) -
Lombardi Rosina A.,
Nafie Laurence A.
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20816
Subject(s) - vibrational circular dichroism , chemistry , birefringence , infrared , dispersion (optics) , spectrometer , spectral line , optics , atomic physics , circular dichroism , molecular physics , physics , crystallography , quantum mechanics
Abstract We report the first mid‐infrared observation of vibrational circular birefringence (VCB) arising from individual chiral molecules. VCB can also be called vibrational optical rotatory dispersion (VORD) and is the Kramers‐Kronig transform of vibrational circular dichroism (VCD). The method of measurement involves a simple change in the optical set‐up and electronic processing of a VCD spectrometer such that the VCB spectrum appears at twice the polarization modulation frequency as a pseudo vibrational linear dichroism (VLD) spectrum. VCB spectra are also calculated with density function theory (DFT) for the first time using a commercially available program for rotational strengths where the calculated intensities are convolved with the real, dispersive part of a normalized complex Lorentzian lineshape rather than the imaginary, absorptive part, normally used for IR and VCD intensity calculations. Comparison of themeasured and calculated VCB, VCD, and IR spectra of (+)‐ R ‐limonene and (−)‐ S ‐α‐pinene show close agreement and confirm the validity of the new VCB measurements. Chirality 21:E277–E286, 2009. © 2009 Wiley‐Liss, Inc.