Color Centers in MgF2

Abstract

The effects of radiation temperature and intensity on the colorability of MgF 2 single crystals obtained from various commercial sources were investigated. The results show that the radiation-damage process in MgF 2 is photochemical in nature and strikingly similar to that in the alkali halides. In the past it has been proposed that long-range focusing events are, in part, responsible for the photochemical coloration of the alkali halides. However, in MgF 2 there are no obvious long-range focusing directions, and the data suggest that such a process is not necessary for the production of photochemical damage. The radiation equilibrium observed to prevail between F and M centers in KG is also evident in MgF 2 , and this effect was used to propose that absorption bands at 370 and 400 nm are due to M centers.

Optical and microstructural properties of MgF2 UV coatings grown by ion beam sputtering process

“…In the past, extensive research activities were focused on the creation of color centers in MgF 2 crystals. [10][11][12] From this work, we know that many kinds of color centers can be generated in MgF 2 crystals, the most frequent ones being the F center which induces an absorption peak centered at ϭ250-260 nm and the M center located at ϭ370 nm. In order to clearly elucidate the kind of centers which are responsible for the absorption we found in our film, we have tried to fit our experimental curves using the model developed, for instance, by Dexter.…”

“…This feature is typical of color centers as frequently reported in literature for MgF 2 crystals. 10 In order to check the stability of the absorption observed on the different layers, some of them have been submitted to annealings. Both UV and thermal annealings have been performed.…”

Luminescence Properties of Rb2ZnCl4 and K2ZnCl4 Single Crystals

“…I n the case of KJnCl, (SG), the weak bands occurring a t 330, 430, and 470nm experience a rapid growth for irradiation temperatures above = 130 K, reach a maximum intensity a t = 190 K, and then decrease for irradiation temperatures above 6. TL spectra of K,ZnCI, (SG) and Rb,ZnC1, measured at 540 nm (solid line) and 330 nm (dotted line) for samples X-irradiated a t 10 K for 1 h…”

Quenching of excitonic luminescence of alkaline earth fluorides excited by VUV harmonics of femtosecond laser

“…Fig. 2 shows the spectral distribution of fast emission (integrated over initial 5 ns) and slow component of STE emission, together with induced absorption spectra [8,9]. We perform measurements at T ¼ 300 K, whereas induced absorption have been measured at 10 K. Nevertheless, the overlapping of these spectra shows the possibility of energy transfer from excitons to radiation defects.…”