On the decay properties of the M' center in LiF crystals

For the first time properties concerning the luminescence decay time as well as the relative quantum yield of M' center in LiF X-ray irradiated samples are simultaneously and accurately investigated as a function of temperature in the range 12.5 to 335 K. Some discrepancies are found between the decay time values and those obtained by other authors in incomplete runs of measurements. The explanation of this difference may be connected to the coloration process and in particular to the generally high M' center concentration: on the contrary the M' center concentration in the samples investigated is low but nevertheless typical for laser operation. Data analysis indicates that more than one nonradiative process is involved in the M' center decay. It is also ascertained that at fixed temperatures the decay time is independent of the M' center concentration in the range investigated (i.e., restricted to low concentrations) and of the ageing of the samples. (author)