title: Electroabsorption spectroscopy of 6-hydroxyquinoline doped in polymer films: Stark shifts and orientational effects.
abstract: 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.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Mohan Singh
authors.initials: MS
authors.lastname: Mehata
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Iimori
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yoshizawa
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ohta