To answer the question of whether special Shpol'skii guest-host combin
ations which exhibit well-defined trapping sites are essential for sin
gle molecule spectroscopy, we have reinvestigated at high-resolution t
he fluorescence of single molecules of terrylene. Our experiments have
demonstrated that similar to the well-known terrylene-n-decane ''Shpo
l'skii'' system, spectra of comparable quality and with lifetime-limit
ed linewidths of about 50 MHz can also be obtained in several mixtures
of alkanes. In the light of these results we then discuss the prospec
ts for single molecule (or single ion) spectroscopy in rare gas matric
es. (C) 1998 Elsevier Science B.V.