Accession Number : ADA295675

Title :   Dicarbocyanine Dyes in Methanol Solution Probed by Rayleigh and Hyper-Rayleigh Light Scattering.

Descriptive Note : Technical rept.,

Corporate Author : NEBRASKA UNIV LINCOLN DEPT OF CHEMISTRY

Personal Author(s) : Song, Ok-Keun ; Wang, C. H.

PDF Url : ADA295675

Report Date : 30 JUN 1995

Pagination or Media Count : 25

Abstract : The hyper-Rayleigh scattering (HRS) intensity of two symmetric carbocyanine dyes (1122DEDC and 1144DEDC) in methanol is measured as a function of dye concentration. These dye molecules at equilibrium show no permanent dipole moment. The low concentration data showing the HRS intensity is proportional to the dye concentration are used to determine the first order hyperpolarizability for each of these dyes. However, above concentration rho(sub b) 0.1 x 10(exp -3) M, the HRS intensity shows an anomalous concentration dependence. Above rho(sub b), the HRS shows a saturation behaviour and even decreases with increasing concentration at high dye concentration. At lowest concentration, the depolarization ratio obtained is consistent with that expected for molecules with C(sub 2v) symmetry. As the dye concentration increases, the depolarization ratio also increases rapidly but the increase quickly saturates as concentration exceeds rho( sub b). The concentration dependence of the HRS intensity and depolarization ratio are interpreted as due to formation of molecular aggregrates. The depolarized Rayleigh scattering (DRS) intensity is also measured as a function of dye concentration. The result of DRS corroborates well that found of HRS. jg

Descriptors :   *LIGHT SCATTERING, *CARBON, *RAYLEIGH SCATTERING, *METHANOLS, *DYES, *CYANINE DYES, RATIOS, HIGH RATE, MOLECULES, EQUILIBRIUM(GENERAL), SATURATION, SOLUTIONS(GENERAL), DEPOLARIZATION, CONCENTRATION(CHEMISTRY), DIPOLE MOMENTS.

Subject Categories : Coatings, Colorants and Finishes
      Organic Chemistry
      Physical Chemistry
      Optics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE