A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing....A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing.For the ground state,the molecular hyperpolarizabilityγg increases with the red-shift of the absorption peakλabmax,of the squaraine with different substituents,whereas for the excited-state molecular hyperpolarizabilityγe,the nonlinear enhancementγe/γg decreases,which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.展开更多
基金the National Natural Science Foundation of China under Grant Nos.19734040,and 69778014.
文摘A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing.For the ground state,the molecular hyperpolarizabilityγg increases with the red-shift of the absorption peakλabmax,of the squaraine with different substituents,whereas for the excited-state molecular hyperpolarizabilityγe,the nonlinear enhancementγe/γg decreases,which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.
