Molecules as single photon source are tuned to the absorption by atoms https://www.mpg.de/8200796/molecules-single_photon
The emission of single photons from molecules, such as dibenzanthanthrene, can be tuned to the atomic absorption of alkali metals, such as sodium. A team of researchers headed by I. Gerhardt’s at the Max Planck Institute for Solid State Research and the University of Stuttgart combine the single-photon source with a sodium vapour cell as a filter and for the processing of quantum information.
They then froze a thin film of the solution at 1.4