Generation of light in doped molecular crystals

A study was made of the spectra and other characteristics of the luminescence emitted by naphthalene single crystals containing ββ'-dinaphthylethylene and biphenylyl–β–naphthylethylene impurities. These crystals were excited by the third harmonic of a neodymium laser. Above the threshold the spectrum consisted of single-line radiation which was polarized and directional.