Quasi-line phosphorescence spectra of the copper complex of meso-tetrapropylporphin at liquid helium temperature

Abstract
Quasi-line spectra of the 4 T 1→2 S 0 phosphorescence of Cu meso-tetrakis(n-propyl)porphin in n-octane at 4.2 K under wide-band and selective excitation have been obtained and analysed. A non-typically large distance between the edge components of the origin ‘multiplet’ (175 cm−1) indicating the sensitivity of the energy of the 0-0 transition of molecular impurity centres to the surroundings has been noted, which can lead to a significant inhomogeneous broadening in amorphous media. Two vibrations with frequencies of about 220 cm−1 are predominantly active in the phosphorescence spectrum. Unlike Cu porphin, the intensity of the corresponding quasi-lines is lower than the intensity of the 0-0 transition. From the broadening of the Q(0-0) band in the phosphorescence excitation spectrum at selective recording of the 0-0 quasi-line the lifetime of the level 2 S 1 (Q) has been determined as 35 fs.