Study on the third-order nonlinear optical properties of bis(tetrabutylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato)cadium

A dmit2− salt: bis(tetrabutylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) cadium (BCDT) was synthesized. The Optical Kerr Effect (OKE) signal of its acetone solution was measured by femtosecond optical Kerr gate technique. Using CS2 OKE signal as reference signal measured under identical conditions, the third-order optical nonlinear susceptibility, χ(3), of the sample solution was obtained to be about 1.08 × 10−13 esu at the concentration of 3.4 × 10−4 M. The second-order hyperpolarizability for BCDT molecular was estimated to be as large as 1.9 × 10−31 esu. Its response time was about 239 fs, which is believed to be the contribution from the delocalized electrons.