CIDEP STUDIES OF CAROTENOID RADICAL CATIONS

Time-resolved electron paramagnetic resonance (TREPR) studies of radic al cations formed by 308 nm photoexcitation of several carotene analog ues are reported. The spin-polarized EPR spectra are weak in intensity and have very broad line widths. Assignment is based on polarization patterns and on the time scales of the signals. Comparisons of g facto rs and line widths are made to the values of radical cations generated electrochemically from the same compounds and the results are discuss ed in terms of proposed radical structures. A dramatic solvent depende nce of the signals is observed.