Aggregation Effect on the Third-Order Optical Nonlinearity in 4-(N,N-Diethylamino)-β-Nitrostyrene-Doped Polymer Films
Aggregation Effect on the Third-Order Optical Nonlinearity in 4-(N,N-Diethylamino)-β-Nitrostyrene-Doped Polymer Films
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4-(N,N-二乙氨基)-β-硝基苯乙烯掺杂聚合物薄膜中三阶光学非线性的聚集效应
DOI：
10.1143/jjap.38.4056
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
H. Shigekawa
中科院分区：
文献类型：
--
作者：
H. Murakami;R. Morita;M. Yamashita;H. Shigekawa
测量了4-(N，N-二乙氨基)-β-硝基苯乙烯掺杂聚甲基丙烯酸甲酯薄膜在0.1wt%~40wt%范围内的吸收光谱和电吸收光谱。测定了三阶非线性极化率χ(3)(-ω；0，0，ω)在各浓度下的色散。此外，还评估了静态极化率变化Δα和静态偶极矩变化Δµ。此外，还测量了0.1-40wt%DEANST掺杂PMMA薄膜的皮秒发射-衰变曲线和时间分辨发射光谱。实验结果表明，DEANST分子在PMMA薄膜中的聚集浓度大于5wt%。这种聚集产生了两个新的吸收带。聚集态对分子间相互作用的影响导致Δµ、平均有效三阶分子超极化率Ef和|χ(3)(-ω；0，0，ω)|的非比例行为随掺杂浓度的增加而减小。此外，这种聚集还解释了吸收光谱的变化、EA光谱的移动以及两个发射-衰变常数随浓度的存在。最后，DEANST分子的平均聚集数为2，这表明当DEANST分子在PMMA膜中的浓度超过5wt%时，DEANST分子在PMMA膜中形成二聚体。
The absorption and electroabsorption (EA) spectra for 4-(N,N-diethylamino)-β-nitrostyrene (DEANST)-doped poly(methyl methacrylate) (PMMA) films in the dopant concentration range of 0.1–40 wt% were measured. Dispersion of the third-order nonlinear optical susceptibility χ(3)(-ω; 0,0,ω) at each concentration was determined. In addition, the static polarizability change Δα and the static dipole-moment change Δµ were evaluated. Furthermore, the picosecond emission-decay profiles and the time-resolved emission spectra for 0.1–40 wt% DEANST-doped PMMA films were measured. From the experimental results, it was concluded that DEANST molecules in PMMA films aggregate at concentrations over 5 wt%. This aggregation gives rise to two new absorption bands. The intermolecular interaction affected by aggregation causes a decrease in Δµ, in the average effective third-order molecular hyperpolarizability eff, and in the nonproportional behavior in |χ(3)(-ω;0,0,ω)| with increasing dopant concentration. Furthermore, this aggregation explains the absorption spectral change, the EA spectral shift and the existence of two emission-decay constants with concentration. Finally, the average aggregation number of DEANST molecules was evaluated to be two, which suggests that DEANST molecules in the PMMA film form a dimer at concentrations over 5 wt%.