在电荷转移化合物晶体高效的上转换荧光.doc

Efficient up-conversion fluorescence in charge transfer compound crystal H. Z. Wang, X. G. Zheng, W. D. Mao, Z. X. Yu, and Z. L. Gao Institute for Laser and Spectroscopy, Zhongshan University, Guangzhou 510275, People’s Republic of China G. Q. Yang, P. F. Wang, and S. K. Wu Institute of Photographic Chemistry, Academia Sinica, Beijing 100101, People’s Republic of China （Received 18 January 1995; accepted for publication 25 March 1995 ） A series of new intramolecular charge transfer compounds with absorption bands in shorter wavelengths have been synthesized. Bright visible light emits from the crystals of these new compounds under infrared pulsed laser pumping. The spectral and pump density dependent properties demonstrate that some of the emissions are up-conversion fluorescence due to two photon absorption. The fluorescent yields of one- and two-photon absorption are in the same order at high pump density. This work demonstrates that these new intramolecular charge transfer crystals are good candidates for nonlinear optical materials. ? 1995 American Institute of Physics. Charge separation is an important physical process. It plays an important role in many physical, chemical, and biological processes. Especially, study on the mechanism of charge separation in photosynthetic reaction center is an important subject. Since the 1980’s, many charge transfer compounds have been synthesized as charge separation molecular models of photosynthetic reaction center. All of these compounds are strongly absorbing in the visible. Recently, we have synthesized a series of new intramolecular charge compounds (derivatives of pro-panedinitrile and pyrazoline) with absorption bands in shorter wavelength. Some of them are transparent in thewavelength longer than 530 nm, and some are transparent in the wavelength longer than 550 nm. We have found that some crystals of these new compounds possess extremely high efficiency of up-conversion fluorescence, and some of them possess ve