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Proceedings Paper

Determination of geometry of 1:1 molecular complexes in solution by hyper-Rayleigh scattering
Author(s): Sampa Ghosh; Puspendu K. Das
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Paper Abstract

Based on the theoretical finding that the geometry of 1:1 complexes formed between two molecules containing planar aromatic rings, governs the relative contribution of the molecular first hyperpolarizability tensor elements to the total hyperpolarizability (β), we have demonstrated how the geometry of such complexes in solution can be described. Hyper-Rayleigh scattering (HRS) technique has been used to measure the second harmonic (SH) scattered light from the complexes in a polarization resolved manner along two mutually perpendicular directions (X and Z) in the laboratory frame (XY being the plane of linear and circular polarization and Z being the direction of propagation of the polarized incident light beam). The macroscopic depolarization ratios, D and D' obtained from the polarization resolved HRS measurements are analyzed to obtain the geometry of two 1:1 electron donor-acceptor complexes between p-xylene and tetrachloro-p-benzoquinone, and durene and dichlorodicyano-p-benzoquinone. The typical values of the two depolarization ratios, D and D', for a planar molecule with C2v symmetry are 0.2 and 0.33, respectively. The D and D' values obtained for the complexes are higher at ~0.24 and ~0.4, respectively. This implies a deviation of the complex geometry from the C2v symmetry that is expected from a perfect cofacial or T-shape structures. Perhaps, a twisted V shape with tilt and twist between the two molecular planes would explain the geometry of the complexes.

Paper Details

Date Published: 20 August 2009
PDF: 9 pages
Proc. SPIE 7413, Linear and Nonlinear Optics of Organic Materials IX, 74130N (20 August 2009); doi: 10.1117/12.824542
Show Author Affiliations
Sampa Ghosh, Indian Institute of Science (India)
Puspendu K. Das, Indian Institute of Science (India)

Published in SPIE Proceedings Vol. 7413:
Linear and Nonlinear Optics of Organic Materials IX
Theodore G. Goodson III, Editor(s)

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