CdS_(0.1)Se_(0.9)纳米晶体共振电吸收谱的线形分析

Line-shape analysis of electroabsorption spectrum of CdS_(0.1)Se_(0.9) nanocrystals

采用电调制技术在室温下测量了 Cd S0 .1 Se0 .9纳米晶体的电吸收谱 ,并对电吸收谱线形进行了分析。纳米晶体与第一个吸收峰有关的电吸收谱结构具有吸收系数对能量的二阶微商特征 ,表明第一激发态在电场作用下以吸收谱线的宽化为主 ,而纳米晶体尺寸不单一是吸收谱线宽化的主要因素。共振电光响应信号的峰值位置、过零点位置以及电吸收谱的线形几乎不随外电场强度而变化 ,信号幅度随外电场强度的平方线性增加。 Cd S0 .1 Se0 .9纳米晶体的电光效应是Kerr效应 ,纳米晶体具有三阶非线性光学极化率 Χ( 3 )。

The electroabsorption spectra of CdS 0 1 Se 0 9 nanocrystals are measured with modulation technique, and the line shape analysis of the electroabsorption spectra is performed The structure of electroabsorption spectra corresponding to the first absorption peak shows the second derivative features of zero field absorption It indicates that the broadening of absorption spectrum is dominant when an external field is applied The features (maxima, minima, positions passing zero, and half linewidths of electroabsorption spectra) do not change with external field It predicates that the origin of the second derivative line shape is the large distribution of nanocrystal size The magnitudes of electroabsorption signal increase quadratically as the elxternal field strength increase This quadratic dependence means that the electro optic effect of CdS 0 1 Se 0 9 nanocrystals is the Kerr effect and the nanocrystals have the third order optical susceptibility Χ (3)