N. Kirov

Vibrational and rotational contribution to IR and Raman bands of uniaxially aligned systems

Abstract Fourier analysis of IR and Raman bands is employed to obtain the vibrational and reorientational correlation functions of uniaxially aligned systems. New equations for separation and quantitative evaluation of the vibrational and rotational contributions to the total IR and Raman bandshape either by Fourier transformation or by direct measurements of the half-widths are suggested.

Two-photon-resonance four-wave mixing for the study of permanent molecular dipoles

Two-photon-resonance four-wave mixing (TPR-FWM) spectroscopy was examined for the study of the permanent electric dipole moments of molecular states. A TPR-FWM process of the type in a three-state x 4 = x 1 O x 2 + x 3 dipolar system was considered. The extraction of data for the di†erence in permanent dipole moments (Dl )o f states involved in TPR was analysed in the case of resonance TPR-FWM. Resonance TPR-FWM measurements were performed in a solution of the polydiacetylene poly-4BCMU. 1998 John Wiley & Sons, Ltd.

IR and Raman bandshape analysis of rotational relaxation in ordered fluids

Abstract Fourier analysis of IR and Raman bands is used to obtain the reorientational correlation functions of aligned anisotropic fluids. New equations for the simultaneous determination of orientational order parameters, the rotational diffusion coefficients and the reorientational relaxation times in anisotropic ordered systems are suggested.

Multiplex CARS spectroscopy of Rochelle salt crystal

Abstract An optical four-wave mixing (FWM) described by the nonlinear susceptibility x (3) ( ω as = 2 ω p − ω s ) is studied in a single crystal of Rochelle salt (NaKC 4 H 4 O 6 ·H 2 O). In addition to the coherent anti-Stokes Raman Scattering (CARS) structure, the FWM spectra consist of nonvibrational (background) components. After analysis of the FWM spectra in the range from 1100 to 1450 cm −1 , the nonresonant (electronic) susceptibility elements x el zzzz and x el xxxx of Rochelle salt single crystal are estimated.

Nonlinear optics in materials: integral transformation of optical four-wave mixing spectra

We analyze the estimation of the third-order susceptibility χ(3) of nonlinear optical (NLO) materials by means of a Hilbert transformation applied to their optical four-wave mixing spectra. In particular, the coherent anti-Stokes Raman scattering (CARS) spectrum is considered. In this case, the integral line-shape processing enables the determination of the excitation profile for resonance CARS (RCARS), or the ratio χR/χEL between the Raman susceptibility and the electronic susceptibility, if nonresonance CARS is performed. As an illustration, we use this procedure to evaluate χEL for a NLO polymer in solution.