Structural changes upon electronic excitation in 1,3-dimethoxybenzene from Franck-Condon/rotational constants fits of the fluorescence emission spectra

摘要

The geometry changes of two rotamers of 1,3-dimethoxybenzene were determined from a combined fit of line intensities in fluorescence emission spectra, obtained via pumping different vibronic transition and the changes of rotational constants upon electronic excitation. The so determined changes are compared to the results of ab initio approximate coupled cluster singles and doubles (CC2) calculations. The bond length variations in the aromatic ring follow the calculated electron density differences from the coupled cluster wavefunctions and are in agreement with excitation to an L-1(b)-state for the C-2v symmetric B-conformer. (C) 2021 Elsevier B.V. All rights reserved.