title: Raman second hyperpolarizability determination using computational Raman activities and a comparison with experiments.
abstract: Doubly vibrationally enhanced (DOVE) four-wave mixing spectroscopy, an optical analogue to 2D NMR, involves two infrared transitions and a Raman transition. The magnitude of the DOVE second hyperpolarizability γ (or third-order susceptibility χ((3))) can be theoretically estimated if the values of the dipolar moments of the two infrared transitions and the γ of the Raman transition are known. The Raman γ can be measured by using the four-wave mixing interferometric method or conventional Raman spectroscopy in the presence of an internal standard. In this work, we examine if one can use the Raman activity computed from density functional theory calculation to determine the Raman γ of selected vibrational modes of several samples including deuterated benzene, acetonitrile, tetrahydrofuran, and sodium benzoate aqueous solution. The 992 cm(-1) Raman band of benzene serves as an internal standard for organic solvents, and the 880 cm(-1) Raman band of hydrogen peroxide is for the aqueous solution sample with known γ values. We have found that the predicted Raman γ values from the computational Raman activities match experimental data reasonably well, suggesting a facile approach to predict the Raman γ of interested systems.
authors.affiliation: Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, Arkansas 72204, USA. wxzhao@ualr.edu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Anqi
authors.initials: A
authors.lastname: He
authors.forename: Yizhuang
authors.initials: Y
authors.lastname: Xu