Mechanism of photoluminescence excitation of Mn2+ ions in ZnS crystals

Abstract

535.37The mechanisms of photoluminescence excitation of Mn 2+ ions in ZnS crystals have been investigated on the basis of complex analysis of the temperature dependences of the photoluminescence and photoluminescence-excitation spectra of ZnS:Mn crystals. The activation energy of a manganese luminescence center was estimated at E a = 0.17 0.05 eV. It is shown that E a represents an energy band with a width ∆E a = 0.1 eV, within which a manganese luminescence center can experience radiationless recombination.Keywords: temperature dependence of photoluminescence spectra, luminescence center of manganese, excitation spectrum, activation energy of manganese center, ZnS crystals.Introduction. Zinc sulfide crystals doped with Mn 2+ ions have long been studied. However, up to now, there has been no clear idea on the mechanisms of transfer of the excitation energy to different manganese centers (MC) of luminescence in zinc sulfide crystals exposed to temperature action or exciting radiation. At the same time, such information would allow one not only to predict the operation of various luminescent devices based on ZnS:Mn cryctals, but also to widen fundamental notions of the monomolecular-luminescence process as a whole.An our opinion, the indicated problems can be solved by investigating, in complex, the photoluminescence and photoluminescence-excitation spectra of ZuS:Mn crystals with different concentrations of an activator at different exciting-radiation energies and temperatures.Samples and Experimental Procedure. ZnS:Mn crystals grown from a melt under an argon pressure by the Bridgman-Stockbarger method [1] were investigated. The concentration of Mn 2+ ions in a mixture was equal to C Mn = 1⋅10 −4 -5⋅10 −2 g of MnS/g of Zn (hereinafter g/g). As the exciting radiation sources, we used LGN-517 lasers with a radiation wavelength λ exc = 441 nm corresponding to the absorption band of Mn 2+ ions in ZnS crystals and

Manganese Clusterization in ZnS:Mn, Mg Synthesized by Self-Propagating High-Temperature Synthesis

“…The LES of the ZnS:Mn, Mg-SHS contains a band with λ max 340 nm associated with fundamental absorption in ZnS, as well as bands with λ max ~ 419, 435, 468, and 493 nm corresponding to the known [29][30][31] manganese LES bands. The latter are caused by the intracenter transitions of Mn 2+ ions from the ground state A 1 to the excited states 4 T 1 , 4 T 2 , 4 E 1 , and 4 A 1 [30,31]. It is seen from Fig.…”

Аналітичний І Синтетичний Підхід У Побудові Моделі Системи Випромінювальних Центрів Монокристалічних З'єднань З Широким Спектром Люмінесценції

“…Следовательно, с теоретической точки зрения остается неясным, почему в качестве элементарной следует брать гауссову, а не какую-нибудь иную, например, колоколообразную форму. В работах [1,7] приводится модель конфигурационных координат, из которой следует, что как раз в энергетических координатах спектр люминесценции может иметь гауссову форму только в том случае, если участок потенциальной кривой основного состояния, расположенный под областью минимума возбужденного состояния, можно заменить отрезком прямой. Во всех остальных случаях спектр люминесценции не будет иметь гауссовой формы.…”

Temperature dependence of photoluminescence and electroluminescence of ZnS:Mn crystals

“…Starting from C Mn = 1⋅10 -3 g/g, the distances between manganese centers prove to be sufficient for resonance interaction to occur between them [3,6,7]. However, according to the data in [8], transfer of the excitation energy of the manganese centers by means of a resonance interaction between them is not predominant, since at the wavelength of the exciting light λ ex = 441 nm, the changes in the intensity of the photoluminescence spectra as the temperature varies are several of orders of magnitude smaller than in the case of excitation by light with λ ex = 337 nm, when only resonance mechanisms can occur for transfer of the photoluminescence excitation energy. For C Mn ≥ 5⋅10 -2 g/g, the pattern changes.…”

“…For C Mn ≥ 5⋅10 -2 g/g, the pattern changes. The resonance mechanism for energy transfer predominates over direct absorption of the energy of the exciting light [8]. The changes in the photoluminescence intensity are large as the temperature varies.…”

“…One of these exponentials, according to (8), decreases while the other increases as the field strength (E) increases. Thus if in the low-field region we neglect the term b 1 E 1/2 and in the high-field region we neglect the term b 2 /E 1/2 , then in the first case the change in the brightness of electroluminescence is described by law (3) and in the second case it is described by (2).…”