Rotationally Resolved Electronic Spectra of 1,2-Dimethoxybenzene and the 1,2-Dimethoxybenzene−Water Complex

Rotationally resolved S1 ← S0 electronic spectra of 1,2-dimethoxybenzene (DMB) and its water complex have been observed and assigned. The derived values of the rotational constants show that the bare molecule has a planar heavy-atom structure with trans-disposed methoxy groups in its ground and exci...

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Published inThe journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 109; no. 42; pp. 9456 - 9464
Main Authors Yi, John T, Ribblett, Jason W, Pratt, David W
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 27.10.2005
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Summary:Rotationally resolved S1 ← S0 electronic spectra of 1,2-dimethoxybenzene (DMB) and its water complex have been observed and assigned. The derived values of the rotational constants show that the bare molecule has a planar heavy-atom structure with trans-disposed methoxy groups in its ground and excited electronic states. The transition of DMB is polarized along the b-axis bisecting the methoxy groups, demonstrating that its S1 state is an 1Lb state. Higher energy bands of DMB are also polarized along the b-axis and have been tentatively assigned to different vibrational modes of the 1Lb state. The water complex origin appears 127 cm-1 to the blue of the bare molecule origin. Analyses of the high resolution spectra of DMB/H2O and DMB/D2O suggest that the water molecule is attached via two O−H···O hydrogen bonds to the methoxy groups in both electronic states. A tunneling motion of the attached water molecule is revealed by a splitting of these spectra into two subbands. Potential barriers to this motion have been determined.
Bibliography:ark:/67375/TPS-C0PKM9G4-D
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ISSN:1089-5639
1520-5215
DOI:10.1021/jp053254l