title: Probing two-photon properties of molecules: large non-Condon effects dominate the resonance hyper-Raman scattering of rhodamine 6G.
abstract: Experimentally measured resonance hyper-Raman (RHR) spectra spanning the S(1) ← S(0), S(2) ← S(0), and S(3) ← S(0) transitions in rhodamine 6G (R6G) have been recorded. These spectra are compared to the results of first-principles calculations of the RHR intensity that include both Franck-Condon (A-term) and non-Condon (B-term) scattering effects. Good agreement between the experimental and theoretical results is observed, demonstrating that first-principles calculations of hyper-Raman intensities are now possible for large molecules such as R6G. Such agreement indicates that RHR spectroscopy will now be a routine aid for probing multiphoton processes. This work further shows that optimization of molecular properties to enhance either A- or B-term scattering might yield molecules with significantly enhanced two-photon properties.
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
authors.forename: Chris B
authors.initials: CB
authors.lastname: Milojevich
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Silverstein
authors.forename: Lasse
authors.initials: L
authors.lastname: Jensen
authors.forename: Jon P
authors.initials: JP
authors.lastname: Camden
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D008958:Models, Molecular; D017785:Photons; D012235:Rhodamines / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines; C026188:rhodamine 6G