On the Fluorescence of Synthetic LiF Crystals

The relative spectral distribution of the fluorescence of both untreated and radiationcoloured LiF crystals have been investigated at monochromatic excitation in the range from 253 to 635 nm. Fluorescence has been shown to be slightly influenced by the growing procedure of the crystals (air or vacuum‐grown) and the type of coloration (x‐rays or deuterons), but it was not until longer exciting wavelengths were used that this influence became more distinct. Fluorescences with peaks at 530 nm and 670 nm emitted at R 1 , R 2 or M band excitation could be verified. In addition, at F band excitation an emission was observed likewise at 530 and 670 nm, which could also be stimulated, individually or commonly, by light of the R 1 , R 2 or M bands. This may be interpreted in terms of an energy transfer process from the absorbing to the emitting centres.