Electroabsorption spectroscopy is used to investigate the fifth-order nonlinear optical property of a polydiacetylene poly-1,6-dicarbazolyl-2,4-hexadiyne [poly(DCHD)] nanocrystal film assembled by sequential ionic adsorption. The fifth-order susceptibility spectrum clearly identifies the vibrational states, i.e., the double bond and triple bond stretching, which are not resolved in the linear absorption spectrum. These vibrational energies are consistent with those obtained from poly(DCHD) bulk crystal through Raman and electroreflectance spectroscopy at low temperatures. The contributions from the vibrational states are also included in the expressions of hyperpolarizabilities for the electro-optical process. The fit of the experimental data shows excellent agreement between the model and the experiment.
© 2005 Optical Society of America
Ke Yang, Jin-An He, Jayant Kumar, Lynne A. Samuelson, Toshiyuki Oshikiri, Hideyuki Katagi, Hitoshi Kasai, Shuji Okada, Hidetoshi Oikawa, Hachiro Nakanishi, and Sukant K. Tripathy, "Study of a poly-1,6-dicarbazolyl-2,4-hexadiyne nanocrystal film by the fifth-order electroabsorption spectroscopy," J. Opt. Soc. Am. B 22, 623-632 (2005)