A few examples of recent progress in the study and applications of purely electronic zero-phonon line (ZPL) and its offshoots are briefly considered: new experimental values of the narrowest ZPL; time-and-space-domain holography in the femtosecond domain, and the realization of a femtosecond Taffoli gate by it; single-impurity-molecule spectroscopy, its relation to single-photon interference and to the realization of quantum computing; the promises of quantum computing compared to what has already been done in holography.
Spectroscopies of matrix isolated species and impurity activated solids are close relatives. Both are among the well developing chapters of solid state spectroscopy and optics. In this paper I am trying to give very brief overview what has been achieved in science and applications of impurity activated solids based on zero-phonon lines (ZPLs) in optical data storage and processing. I would like to show that the latter comprises via persistent spectral hole burning time-and-space domain holography in a certain meaning also the "stopping of light". ZPLs are beginning to play a role in the approaches to optical quantum computing.