Dispersion of X(3) in Polydiacetylene Films from Electroabsorption Spectroscopy

摘要

Electroabsorption spectroscopy was carried out on a polydiacetylene, poly.8-BUTOXY CARBONYL methyl urethanyl 1-(5-pyrimidyl) -octa-1, 3-diyne (poly(BPOD)) film from 470nm to 730nm, and on a polydiacetylene poly-(butoxycarbonyl methyleneurethane) (poly(4-BCMU)) film from 400nm to 700nm. The dispersion of the imaginary part of the complex Xeff(3) , which is a combination of X1133(3)(w;w,0,0), and X3333(3)(w;w,0,0) was directly determined from experiment. The real part of Xeff(3) was calculated from its imaginary part by Kramers-Kronig relation. The complex susceptibilities X1133(3)(w;w,0,0) and X3333(3) (w;w,0,0), were thus obtained from Xeff(3) determined at normal and tilted incidence. The results for both polydiacetylene spin coated films satisfy X3333(3) 1.5X1333(3), and are significantly different from the relation X3333(3) = 3X1333(3), expected for an isotropic film. It indicates that the polymer chain segments in both polydiacetylene films lie mainly on the film plane instead of an isotropic distribution. The X(3) values for both materials are of the order of 10(exp-11) esu. Some enhancement of nonlinearity of poly(BPOD) over poly(4-BCMU) is observed.