Site effects on the electronic relaxation of aromatic molecules in van der Waals solids

Fluorescence and phosphorescence of naphthalene and aniline molecules trapped in cryogenic matrices present site-dependent features. The isolation in solid argon has been especially investigated. Experimental results for naphthalene are summarized and related to the site geometries obtained from molecular dynamics calculations. In the case of aniline, site effects are mainly revealed through the phosphorescence spectra. In particular sites, the measurement of the inversion frequency can be directly extracted.