open access

https://hdl.handle.net/2115/42547

Comparative study of electroabsorption spectra of polar and nonpolar organic molecules in solution and in a polymer film

英語

visible spectra

2009-12-28

American Institute of Physics

Journal of Chemical Physics

131(24)

244509

Electroabsorption (EA) spectra of polar and nonpolar molecules of coumarin 153 (C153) and pyrene in solution and in a polymer film of polymethylmethacrylate (PMMA) have been measured in the UV-visible region at room temperature. The shape of the EA spectra of C153 in benzene, 1,4-dioxane, or monochlorobenzene remarkably depends on the angle between the polarization direction of the absorption light and the applied electric field, whereas the EA spectra of C153 doped in PMMA show only the Stark shift and the field-induced change in spectral shape is negligible. These results demonstrate that C153 is reoriented by application of electric fields in solution, but the molecules are immobilized in a PMMA film. Based on the EA spectra, electric dipole moments both in the ground state and in the excited state have been evaluated for C153 in different solvents. In the EA spectra of pyrene, only the Stark shift is observed both in solution and in PMMA, indicating that the field-induced molecular reorientation does not occur both in solution and in PMMA. The change in dipole moment of C153 as well as the change in molecular polarizability of pyrene following absorption is much larger in solution than that in PMMA.

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Copyright 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Chem. Phys. 131, 244509 (2009) and may be found at https://dx.doi.org/10.1063/1.3268621

0021-9606