Saturation spectroscopy of vibronic transitions in single molecules

A novel technique of saturation spectroscopy is applied to study the individual vibronic spectra of single impurity molecules embedded in a low-temperature solid matrix. Homogeneous linewidths and vibrational frequencies for two lower vibronic levels of the excited electronic state S1 are determined for several terrylene single molecules in a naphthalene crystal, which indicates a noticeable distribution of these parameters. A certain correlation can be pointed out between vibrational frequency and a purely electronic transition frequency of a terrylene molecule.