3CTC AS THE MAIN STEP IN THE QUENCHING OF 3BP BY ELECTRON AND HYDROGEN DONORS

It is shown that the quenching of triplet benzophenone by electron and hydrogen donors involves a charge transfer state (CTC3) as the governing step. Moreover, it is shown for the first time that the aliphatic donors follow fully the simple model of Rehm and Weller for electron transfer: the rate of quenching increases as the ionization potential (IP) of the donor decreases and reaches a limiting value when IP is 9 eV or less, i.e. for most amines. It is confirmed that alkyl benzenes lie on another line. However, the slopes of the pi and n lines are nearly the same in contrast with previous reports. The different behaviour of pi and n quenchers is tentatively addressed.