摘要
通过稳态和时间分辨荧光及二次谐波产生(SHG)的方法研究了2-硝基-5-(N-甲基-N-十八烷基)氨基苯甲酸(NMOB)分子朗缪尔-布罗基特(Langmuir-Blodgett,LB)多层膜的光谱及非线性光学特性。LB膜的稳态荧光谱较溶液红移大。而纯的NMOBY型LB多层膜与NMOB/花生酸交替的LB多层膜之间差别较小;由于分子间的相互作用,使得NMOB分子在溶液中比在LB膜中的荧光衰减时间大。在LB膜中,纯的NMOB和NMOB与花生酸交替的LB多层膜的荧光衰减时间相差不大,说明NMOB分子层内的相互作用较大,而层间的相互作用较小;由于苯环两侧的不对称取代,分子内部形成固有的偶极矩,使得NMOB/花生酸交替的LB多层膜具有较大的宏观偶极矩,因而具有大的二阶非线性极化率,其超分子极化率约为β=4×10-29esu。
Spectra and nonlinear optical properties of 2-nitro-5 （N-methyl N-octadecylamino）benzoic acid （NMOB） in Langmuir -Blodgett （LB） films have been studied by steady state, time-resolved fluorescence and second harmonic generation （SHG）. The steady state fluorescence spectra of NMOB have a big red shift in I.B films than that of in the solution. There was a very small difference comparing pure NOMB Y-type LB multilayer films with NMOB/arachidic acid alternated LB multilayer films. The fluorescence decay time was longer in NMOB solutions than that of in LB films because of inter-molecule interaction. Interaction of intralayer NMOB molecules is bigger than that of interlayer the molecules in Langmui-Blodgett multilayer films. The intramolecular natural dipole was formed because of the bilateral asymmetric substitute of benzene. So a rather large macro-dipole could be formed in NMOB/arachidic acid alternated LB multilayer films. Therefore, NMOB molecules in LB films have a large second order nonlinear optical susceptibility. The hyperpolarizability β was about 4×10^-29esu。
出处
《中国激光》
EI
CAS
CSCD
北大核心
2005年第8期1123-1126,共4页
Chinese Journal of Lasers
基金
国家863计划(2004AA32G090)
山东省自然科学基金(Y2003A02)资助项目。
关键词
薄膜
非线性光学
朗缪尔-布罗基特膜
二次谐波产生
时间分辨荧光
thin film
nonlinear optics
Langmuir-Blodgett films
second harmonic generation
time resolved fluorescence
