ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
As an extension of our previous study on polarizabilities [J. Chem. Phys. 115, 1052 (2001)], we investigate the molecular third-order nonlinear optical properties, i.e., the second hyperpolarizabilities (γ), of three types of model oligomers (made of phenylene vinylenes), i.e., para-oligomers and meta-oligomers with fractal and nonfractal structures, which are considered to be models of dendron parts involved in Cayley-tree-type dendrimers. Similarly to the polarizability case, the chain-length dependence of γ of para-oligomers is found to be much larger than that of nonfractal meta-oligomers, while fractal meta-oligomers exhibit an intermediate chain-length dependency of γ between them. The spatial contributions of π-electrons to γ of these systems are elucidated using hyperpolarizability density analysis. It is found that the spatial contributions of π-electrons to γ of nonfractal meta-oligomers are much smaller than those of para-oligomers and are well decoupled at the meta-substituted benzene rings, while the fractal meta-oligomers show significantly large spatial contributions of π-electrons to γ in their linear-leg (para-substituted phenylene vinylene) regions similarly to the case of para-oligomers although the distributions are also well decoupled at the meta-substituted benzene rings. This feature supports the distinct features of chain-length dependency of γ for these oligomers. © 2001 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.1405123
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