Wavelength dependence of ultrafast and large third-order non-linear optical response of polyacetylene nanoparticles

The third-order optical non-linearity was measured in nanopolyacetylene using femtosecond optical Kerr effect technique at wavelength from 790 to 860 nm. The ultrafast non-resonant effective second-order hyperpolarizibility for single polyacetylene nanoparticle was estimated to be as large as 1.0×10−27 esu, which corresponding to the γc of single carbon atom contribution equals to 5.0×10−33 esu. We ascribed the observations to the highly ordered structure of nanopolyacetylene and delocalization of the π electrons along the conjugated chains was supposed to be responsible for such properties.