Absorption and emission spectroscopy of perylene (C20H12) isolated in Ne, Ar, and N2 matrices

The electronic absorption and emission spectra of perylene (C20H12) isolated in rare gas (Ne, Ar) and N-2 matrices are presented. While the electronic band systems show, in all matrices, the same fundamental frequencies as those observed in gas-phase jet experiments, the spectra in Ar and N-2 matrices exhibit much more spectral structure. The observed structure points to strong host-guest interactions and provides new insight into the low frequency modes of perylene. In particular, the spacing observed at 11 and 16 cm(-1) in the S-0 and S-1 states, respectively, might be attributed to the gerade accordion mode of perylene. This mode, which has never been observed directly in jet experiments, could be induced into activity in solid matrices. (C) 1999 American Institute of Physics. [S0021-9606(99)00915-0].