Knowledge Bank

The optical spectra of Zn porphin single crystal triphenylene at low temperatures have been previously reported and shown to consist of sharp $lines.1$ The spectra were characterized by a triplet structure similar to multiplet structure observed in Shpol’skii spectra. The conjecture that the triplet structure was due to multiple inequivalent site species has been confirmed in the present work by the use of high resolution selective excitation techniques. Absorption (excitation) and fluorescence spectra from each of the three principal site species of in porphin in triphenylene have been observed using a dye laser as an excitation source. These single site spectra reveal the structure of the ground electronic vibrational state and excited singlet electronic state of Zn porphin in triphenylene to an extent not possible with previously observed multiple site spectra. Details of the spectra will be discussed.