MAGNETOOPTICAL SPECTROSCOPY OF THE Q TRANSITION OF ZINC TETRABENZOPORPHYRIN ISOLATED IN AN ARGON MATRIX.

Abstract

Author Institution: Department of Chemistry, University of Canterbury; Department of Chemistry, University of VirginiaAbsorption, fluorescence, magnetic circular dichroism (MCD), magnetic circularly polarized luminscence (MCPL) and longitudinal Zeeman spectra were measured for the $Q(^{1}A^{1}_{g}(\pi)) \rightarrow ^{1}E_{u}(\pi^{*}e)$ transition of zinc tetra benzoporphyrin isolated in an argon matrix (ZnTBP/Ar). Moment analysis of the MCD and absorption yield an excited-state orbital g value of $g_{1} = 7.7 \pm 0.4$. The large value of this parameter is consistent with a four-orbital interpretation of the Q transition for metallophthalocyanines. The magnetic field dependence of the zero-phonon Zeeman shifts and moment analysis of the emission spectra independently yield information concerning Jahn-Teller (JT) effects in the excited state. These data have been interpreted in the context of a single effective JT-active coordinate and local crystal-field distortions of both $b_{1}g$ and $b_{2}g$ symmetry. [FIGURE]