Resonance Raman and hyper-Raman spectroscopy of organic chromophores for second-order nonlinear optics

摘要

Two-photon resonant hyper-Raman spectroscopy from large molecules in solution is discussed as a method for probing excited electronic states that are both one- and two-photon allowed. A number of electron donor-acceptor substituted conjugated organic molecules that have large first hyperpolarizabilities (13) have recently been shown to give strong resonance hyper-Raman (RHR) spectra in solution. The quantum mechanical formulation of RHR scattering is reviewed, and practical approaches to calculating RHR spectra and excitation profiles are proposed by reference to methods already developed for simulating linear resonance Raman spectra and profiles. The potential benefits of a close interplay between experiments, empirical simulations, and electronic structure calculations of ground-state and excited-state properties are emphasized. (c) 2005 Wiley Periodicals, Inc.