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Local field and aggregation dependence of the micro- and macroscopic optical non-linearity of zwitterionic molecules.

Cross, G. H. and Hackman, N. A. and Thomas, P. R. and Szablewski, Marek and Palsson, L. O. and Bloor, D. (2003) 'Local field and aggregation dependence of the micro- and macroscopic optical non-linearity of zwitterionic molecules.', Optical materials., 21 (1-3). pp. 29-37.


When a dipolar-conjugated molecule can lower its energy through gaining aromaticity, there can be a quite dramatic evolution of its polarisation properties dependent on the local reaction field generated in its environment. We have studied conjugated dipolar derivatives of tetracyano-p-quinodimethane (TCNQ) that would have quinoidal structure were it not for even the modest reaction fields produced in any solvent medium or polymer host environment. Measurements of dipole moment, μ, and of the first hyperpolarisability, β, have been undertaken in solvent media of varying polarity. We discuss the evolution of these properties as evidenced by solvatochromism and hyper Rayleigh scattering. We also discuss one major consequence of the planarity and high polarity in these molecules, association between them, which can seriously undermine practical implementation. Nevertheless, we refer to work demonstrating that this common problem can be overcome by suitable steric control of molecular shape and show that the prospects for achieving unprecedented electro-optic coefficients from polymer media are good.

Item Type:Article
Additional Information:I prepared this paper for an invited lecture at a conference in South Korea in 2001. It represents an analysis of experimental data taken at Durham and by collaborators in Belgium.
Keywords:Non-linear optics, Organic molecules, Electro-optic polymers, Aggregation.
Full text:Full text not available from this repository.
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Date accepted:No date available
Date deposited:No date available
Date of first online publication:January 2003
Date first made open access:No date available

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