Rotationally resolved electronic spectra of 1,2-dimethoxybenzene and the 1,2-dimethoxybenzene-water complex.
Rotationally resolved S(1) <-- S(0) 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 S(1) state is an (1)L(b) state. Higher energy bands of DMB are also polarized along the b-axis and have been tentatively assigned to different vibrational modes of the (1)L(b) 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/H(2)O and DMB/D(2)O 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.
Yi
John T
JT
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Ribblett
Jason W
JW
Pratt
David W
DW
D000840:Anisoles / Q000737:chemistry*; D006860:Hydrogen Bonding; D011789:Quantum Theory; D012399:Rotation; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D014732:Vibration; D014867:Water / Q000737:chemistry
D000840:Anisoles; D014867:Water; C005299:veratrole