Review on low-temperature optical dephasing in impurity solid media doped with fluorescent molecules and analysis of the data obtained by different methods of selective laser spectroscopy, including the photon echo and single-molecule spectroscopy are given.
$^1$Department of Molecular Spectroscopy, Institute for Spectroscopy. Moscow, Troitsk 142190, Russia.
$^2$Zavoyski Physical–Technical Institute. Kazan 420029, Russia.
$^3$Moscow Pedagogical State University. Moscow 119991, Russia.