Влияние ультрафиолетового света на люминесценцию (700-1000 nm) кристаллов LiF и LiF : ОН, облученных в ядерном реакторе

The emission (700-1000 nm) and absorption (200-800 nm) spectra of LiF and LiF:OH crystals irradiated in a reactor and exposed to ultraviolet light, including those combined with mechanical loading, have been studied. The aim of this work is to study the behavior of laser color centers in these systems. In the 710–825 nm range, diametrically opposite results are observed: high stability of F4-like centers in “pure” LiF and their sharp destruction in LiF:OH crystals. At the same time, in both groups, F3 and F4 centers are destroyed and F2+ and F3- laser centers (825–925 nm) are intensely accumulated. Upon subsequent exposure at room temperature and darkness, spontaneous disintegration of laser centers is observed, accompanied by an increase of concentration of F4-like centers and restoration of the microstructure of irradiated crystals.

Флуктуирующая флуоресценция одиночных центров окраски в кристаллах фторида лития

Single F2 and F3+- color centers in the LiF crystal were studied by confocal fluorescence microscopy. The time dependences of their fluorescence intensity were analyzed and statistically processed. Our studies show that, the F3+- color center, being photoexcited, is able enter the triplet state, while in ground (singlet) state it changes orientation with a frequency of 1.5 – 2 Hz at room temperature, due to reorientational diffusion, unlike the F2- center, which is reoriented only being in the triplet state. This subtype of rotational diffusion of the center does not lead to its translational diffusion.

Numerical study of silicon vacancy color centers in silicon carbide by helium ion implantation and subsequent annealing

Molecular dynamics (MD) simulation is adopted to discover the underlying mechanism of silicon vacancy color center and damage evolution during helium ions implanted four-hexagonal silicon carbide (4H-SiC) and subsequent annealing. The atomic-scale mechanism of silicon vacancy color centers in the process of He ion implantation into 4H-SiC can be described more accurately by incorporating electron stopping power for He ion implantation. We present a new method for calculating the silicon vacancy color center numerically, which considers the structure around the color center and makes the statistical results more accurate than the Wigner-Seitz defect analysis method. At the same time, photoluminescence (PL) spectroscopy of silicon vacancy color center under different helium ion doses is also characterized for validating the numerical analysis. The MD simulation of the optimal annealing temperature of silicon vacancy color center is predicted by the proposed new method.