I. Ledoux et al., Third-order microscopic nonlinearities of very long chain polyenes: saturation phenomena and conformational effects, CHEM PHYS, 245(1-3), 1999, pp. 1-16
Using the living cyclopolymerization of diethyldipropargylmalonate, very lo
ng polyenes (up to 1100 carbon-carbon double bonds) are now available, Mole
cular masses of these polyenes are determined using the MALDI-TOF technique
. Third-order polarizabilities gamma of polyene-like molecules with very lo
ng conjugation length (N up to 1100 carbon-carbon double bonds) are measure
d using third-harmonic generation at 1.9 mu m in THF solutions. gamma value
s saturate around N = 60 double bonds. Modelization of the dependence of ga
mma with respect to N is based on a representation of a conjugated chain as
a collection of planar segments separated by large angular breaks. A very
good quantitive agreement between calculated and experimental data, both in
terms of saturation length and gamma/N values is clearly demonstrated. (C)
1999 Elsevier Science B.V. All rights reserved.