MAGNETOOPTICAL SPECTROSCOPY OF ZINC TETRABENZOPORPHYRIN IN AN ARGON MATRIX

Absorption and magnetic circular dichroism (MCD) spectra are reported for zinc tetrabenzoporphyrin in an argon matrix (ZnTBP/Ar) over the ra nge 16 000-65 000 cm-1. Application of a moment analysis or least-squa res band fitting yields g(parallel-to) values for 15 excited states. B andwidths for visible transitions are sufficiently narrow to allow det ermination of Jahn-Teller parameters for the lowest excited singlet (Q ) state of the predominant matrix site from Zeeman shifts. Total lumin escence (TL) and magnetic circularly polarized luminescence (MCPL) ass ociated with the lowest triplet and two lowest singlet excited states are also reported. Moment analysis provides estimates of the magnitude of the Jahn-Teller effect in the second excited singlet (B) state and in the Q state of a minor site. The latter is significantly greater t han that obtained from the Zeeman analysis of the major site, which su ggests that the magnitude of the Jahn-Teller effect may be dependent o n the molecular environment.