Zur grünen Lumineszenz des Zinkoxyds

ZnO-phosphors are produced at different reduction temperatures. The hole trap density —indicated by thermoluminescence and phosphorescence — increases with increasing reduction temperature. The maximum of the emission spectrum moves to longer wavelengths with increasing temperature of the sample. Trap saturation and the first part of phosphorescence decay obey approximately exponential laws. Phosphorescence measurements indicate an important influence of retrapping processes. The coefficient for thermal hole liberation can be determined from experimental data. It is possible to obtain values for the depth of the three existing hole trap levels either by optical measurements or by evaluation of glow curves.     

Zur grünen Lumineszens des Zinkoxyds

After thermoluminescence observations [1] at 9 differently reduced ZnO-samples the dependence of the spontaneously emitted green luminescence on intensity, excitation wavelength and temperature is investigated. The spectral distribution depends on the degree of reduction as well as on the temperature of the sample. There is an increase in luminescence output in the region of thermal liberation of holes from the traps. These effects indicate the role of hole traps in the mechanism of spontaneous luminescence. A model for the luminescence mechanism is discussed, basing on the assumption of donor-acceptor-coupling.     

Zur Lumineszenz und Lumineszenzzerstörung von ZnS-Leuchtstoffen

A series of variously doped ZnS-crystals and ZnS-powders exhibits — under different excitation and temperature conditions — the same emission bands. The wavelengths of the maxima of these emission bands are independent of the temperature. The luminescence decay after UV- and electron excitation can be described as a sum of three exponential functions. By ion bombardment the deterioration of the luminescence intensity of each emission band depends hyperbolically on the number of the incident particles. The experimental results are explained by an uniform model of the luminescence center for the variously doped ZnS-samples. The center is proposed to be a perturbed 3d ¹⁰-configuration of the Zn-ion in tetrahedral or octahedral surrounding.     

Lumineszenz der Nacl-Ni-Kristalle

Ohne Zusammenfassung