Electroabsorption spectroscopy of 6-hydroxyquinoline doped in polymer films: Stark shifts and orientational effects
Electroabsorption spectroscopy of 6-hydroxyquinoline doped in polymer films: Stark shifts and orientational effects
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DOI：
10.1021/jp063927f
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发表时间：
2006-09-28
影响因子：
2.9
通讯作者：
Ohta, Nobuhiro
中科院分区：
文献类型：
--
作者：
Mehata, Mohan Singh;Iimori, Toshifumi;Ohta, Nobuhiro
在50-300 K温度范围内，对掺杂在聚甲基丙烯酸甲酯（PMMA）和聚乙烯醇（PVA）聚合物膜中的6-羟基喹啉（6-HQ）进行了斯塔克吸收光谱研究。6-HQ的电吸收（E-A）光谱明显依赖于PMMA膜中的温度。E-A谱的偏振依赖性和温度依赖性表明，在室温下，6-HQ在PMMA膜中沿沿着外加电场方向取向。随着温度的降低，6-HQ的场致取向受到限制，并且仅观察到由电偶极矩和分子极化率的变化引起的斯塔克位移。另一方面，掺杂在PVA膜中的6-HQ的E-A谱基本上与温度无关，这表明即使在室温下，6-HQ在PVA中也不沿着电场取向。这些结果表明，6-HQ在聚合物膜中的分子运动对周围基质的微环境非常敏感。
Stark absorption spectroscopy was applied to 6-hydroxyquinoline (6-HQ) doped in polymer films of poly-(methyl methacrylate) (PMMA) and poly(vinyl alcohol) (PVA) at temperatures of 50-300 K. The electroabsorption (E-A) spectrum of 6-HQ markedly depends on temperature in a PMMA film. The polarization dependence as well as the temperature dependence of the E-A spectra reveals that 6-HQ is oriented along the direction of the applied electric field at room temperature in a PMMA film. As the temperature becomes lower, the field-induced orientation of 6-HQ is restricted, and only the Stark shift induced by a change in electric dipole moment and in molecular polarizability is observed. On the other hand, E-A spectra of 6-HQ doped in a PVA film are essentially independent of temperature, suggesting that 6-HQ is not oriented along the electric field even at room temperature in PVA. These results show that the molecular motion of 6-HQ in a polymer film is very sensitive to the microenvironment of the surrounding matrix.