Structural changes of 1,2-diphenoxyethane upon electronic excitation from a combined Franck-Condon/rotational constants fit.

• The geometry changes of the tgt - and the ttt -rotamer of 1,2-diphenoxyethane have been determined from a combined fit of rotation al constants and fluorescence emission intensities from several vibronic bands. • The geometry changes are compared to the results of ab initio calculations at the spin-component-scaled approximate coupled cluster singles and doubles (CC2) level of theory. • The excitonic splitting of the origins of both rotamers has been determined from ab initio calculations. The geometry changes of the tgt - and the ttt -rotamer of 1,2-diphenoxyethane 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, which were taken from [E.G. Buchanan, P.S. Walsh, D.F. Plusquellic, T.S. Zwier, J. Chem. Phys. 138 (2013) 204313]. The so determined geometry changes are compared to the results of ab initio spin-component-scaled approximate coupled cluster singles and doubles (SCS-CC2) calculations. [ABSTRACT FROM AUTHOR]