Selection Rules and Symmetry Relations for Four-Wave Mixing Measurements of Uniaxial Assemblies
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- 作者：Ryan P. Davis ; Andrew J. Moad ; G. Scott Goeken ; Ronald D. Wampler ; Garth J. Simpson
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：May 8, 2008
- 年：2008
- 卷：112
- 期：18
- 页码：5834 - 5848
- 全文大小：148K
- 年卷期：v.112,no.18(May 8, 2008)
- ISSN：1520-5207
文摘
Uniaxial systems represent the next lowest symmetry below isotropic and are ubiquitous. The objective ofthe present work is to present a systematic foundation for interpreting polarization-dependent four-wave mixingmeasurements of oriented and aligned assemblies. Orientational averages connecting the molecular frame tothe macroscopic frame in uniaxial assemblies were derived for several common molecular symmetry groupsfor coherent anti-Stokes Raman spectroscopy (CARS) measurements, coherent anti-Stokes two-photonspectroscopy (CATS) probing electronic transitions, resonant two-photon absorption (2PA), and traditionalRaman measurements. First, the complete set of orientational averages connecting the molecular andmacroscopic frames was compiled for the most general case of C1 molecular symmetry. Then, the orientationalaverages of a select few commonly occurring molecular symmetry groups (Cs, C2, C2v, and C3v) were exploredin greater detail to illustrate the approach and to facilitate the interpretation of routine experimentalmeasurements. One outcome of this analysis is the prediction of efficient electric dipole-allowed chiral-specific four-wave mixing in uniaxially oriented media.