翠绿亚胺碱的超快光克尔和光致吸收效应

ULTRAFAST OPTICAL KERR EFFECT AND OPTICAL INDUCED ABSORPTION OF EMERALDINE BASE

报道了在飞秒染料激光脉冲作用下对翠绿亚胺碱（ＥＢ）的二甲基甲酰胺溶液的瞬态共振光克尔和光致吸收效应的研究．时间分辨的光克尔实验表明，翠绿亚胺碱溶液的光克尔信号仅表现一超快响应的成分，可归结为其基态和由于单光子共振吸收和双光子吸收产生的激发态的各振动能级与转动能级之间的弛豫过程．同时通过拟合计算分别给出了翠绿亚胺碱溶液的弛豫时间和三阶非线性极化率．抽运探测实验结果表明，翠绿亚胺碱分子的超快响应的光致吸收效应，主要来自于导致该分子中苯环结构π—π跃迁的双光子吸收的贡献．

Abstract The transient optical Kerr effect (OKE) and optical induced absorption of emeraldine base (EB) in dimethylformamide solution have been investigated with femtosecond laser pulses.Only a ultrafast component of OKE of EB solution is observed and its dephasing time is given by theoretical fitting.The third order nonlinear optical susceptibility of EB solution is also determined.Two photon absorption is proved to be the predominant mechanism causing the observed optical limiting behavior.