@Article{JPhysChemA_110_9988, author = {A. Pigliucci and P. Nikolov and A. Rehaman and L. Gagliardi and C.J. Cramer and E. Vauthey}, title = {{Early Excited State Dynamics of 6-Styryl-Substituted Pyrylium Salts Exhibiting Dual Fluorescence}}, journal= {J. Phys. Chem. A}, ISSN = {1089-5639}, volume= {110}, number= {33}, pages = {9988-9994}, url = {http://pubs.acs.org/cgi-bin/abstract.cgi/jpcafh/2006/110/i33/abs/jp063214x.html}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref00827.pdf}, doi= {10.1021/jp063214x}, abstract = {{A series of 6-styryl-2,4-diphenylpyrylium salts exhibiting dual fluorescence has been investigated by fluorescence up-conversion in conjunction with quantum chemical calculations. The short-wavelength emission is due to an excited state localized on the pyrylium fragment and the long-wavelength emission arises from a charge-transfer state delocalized over the whole molecule. The two fluorescing states do not exhibit a precursor-successor relationship. The rise time of the short-wavelength fluorescence is smaller than 200 fs, and that of the long-wavelength emission depends on the electron-donating property of the styryl group substituent. The rise is almost prompt with the weaker donors but is slower, wavelength and viscosity dependent with the strongest electron-donating group. A model involving a S$_2$/S$_1$ conical intersection is proposed to account for these observations.}}, year = {2006} }