Deformation-stimulated Ex luminescence in a RbI single crystal

Abstract

Using X-ray luminescence spectra, the enhancement of both σ-luminescence of self-trapped excitons and Ех luminescence (band maxima at 3.89 and 3.1 eV, respectively) has been revealed for the first time in RbI single crystals exposed to elastic uniaxial stress at 93 K. The intensity of these emissions increases linearly with the relative degree of applied uniaxial deformation of the crystal up to ɛ = 1%, while the luminescence undergoes saturation at higher values of ɛ. The behavior of the I = f (ɛ) dependence for σ and Ех emissions suggests that Ех luminescence is intrinsic, and is connected with the radiative relaxation of self-trapped excitons in the field of local deformation of a RbI regular lattice.

The features of deformation-stimulated RbI luminescence

“…Based on the correlated increase in the intensity of E x -and σ -luminescence with a decrease in the symmetry of the lattice of RbI crystal, it is concluded that the nature of E x -luminescence is not associated with the participation of sodium impurity, as many researchers assumed [8][9]21]. The experimental results obtained in [16] allow us to assume that their E x -luminescence corresponds to the radiative decay of STEs, which has its own nature in RbI crystal.…”

“…The boundary of elastic and plastic deformation is determined experimentally by the linear section of the dependence of the intensity of σ -and E xluminescence on the degree of deformation at which Hooke's law is valid [16]. In this regard, to create only the elastic part of the deformation, the crystals were deformed at low temperature (85 K) within the range of ε = 0.8 − 1.0% in a special cryostat under high technical vacuum conditions [19].…”

“…In the experimental plan, elastic deformation is successfully used not only as a method of influencing the relaxation processes of STEs, but also for recognizing the nature of luminescence in AHCs [15]. For the first time, low-temperature uniaxial elastic deformation was used as an external perturbing factor that reduces the lattice symmetry to solve the problem of the intrinsic or impurity nature of E x -luminescence in KI and RbI crystals [16]. The intensity of intrinsic luminescence of exciton nature correlates with an increase in the degree of elastic deformation, and the intensity of luminescence of impurity nature, on the contrary, will decrease until it disappears, since the transfer of exciton energy to impurities will worsen due to the inclusion of the mechanism of their self-trapping in regular lattice sites [15].…”

О Прозрачности Щелочно-Галоидных Кристаллов В Терагерцовой Области Спектра

“…На приведенном на рис. 5 спектре интенсивная полоса поглощения в районе 7−8 µm вызвана примесью бария (Ba), введенной специально для улучшения сцинтилляционных свойств кристалла, которая не влияет на пропускание кристалла в других областях [28,30,31].…”

Influence of Dislocations Move on Photoluminescence of Mn²⁺ Ions with Various Local Surroundings in ZnS Single Crystals in the Process of Plastic Deformation

“…This leads to a change in the electrical [4,5] and optical characteristics [3,[6][7][8] of the materials under study. In particular, the motion of dislocations that occurs during PD [9,10] changes the immediate environment of luminescence centers and affects the mechanisms of excitation energy transfer, which in turn causes a change in the luminescent properties of deformable materials [11][12][13].…”