A site-selective spectroscopy of naphthalene and quinoline in TEOS/MTEOS xerogels

Fluorescence and phosphorescence spectra and decay times are recorded upon a narrow-band laser excitation for naphthalene (N) and quinoline (Q) embedded in xerogels prepared from MTEOS/TEOS mixtures, in the 10-300 K temperature range. A site selectivity of the excitation is observed at T <120 K and T <150 K, for N and Q, respectively. In the case of quinoline, different families of sites are characterized. The results are discussed in terms of comparison with the N and Q emission behaviour in other environments, especially in rare-gas matrices.