Mollwo-Ivey relations for emission bands in copper doped alkali halides

The fluorescence spectra were measured of nine alkali halides with a low concentration of monovalent copper. Relations analogous to Mollwo-Ivey law for F-centers and for lead doped alkali halides were found to be satisfied by the measured wavelengths corresponding to the emission band maxima. The Stokes shifts, however, were here essentially larger as compared to those of lead doped alkali halides. Their order of magnitude is about the same as for F-centers.Dedicated to Prof. Dr. I. Tarján on occasion of his 60th birthday.Cukrovarnická 10, Praha 6, Czechoslovakia.The authors wish to express their appreciation to Dr. M. Lébl, CSc., and Ing. . Barta, CSc., for growing the crystals and to Mrs. I. Velická for the polarographic analysis.     

Free oscillations of a fluid in a cylindrical container with arbitrary axisymmetric bottom and elastic elements on the free surface of the fluid

We consider the problem of free oscillations of an ideal fluid in a container that has the form of a right circular cylinder with arbitrary axisymmetric bottom in the case where the unperturbed free surface of the fluid is covered by an elastic membrane or plate. Using the expansion in eigenfunctions of an auxiliary spectral problem with a parameter in boundary conditions and the method of decomposition of the domain of meridional cross-section of a container, we obtain an analytic solution of the problem. Individual examples of mechanical systems are considered, for which we construct solutions by using the proposed algorithm, analyze these solutions, and compute the frequencies and forms of oscillations.     

Absorption and thermostimulated electron emission and luminescence of LiF crystals bombarded with alpha particles

The paper gives the results of measuring the absorption and thermostimulated electron emission and luminescence in the same kind of LiF crystals irradiated with X-rays and alpha particles. The different method of excitation has the consequence that the curves of the three phenomena are to a certain extent different. The possible causes of these differences are discussed.The author would like to thank K. Listoová and Z. Klímová for carefully performing the measurements.     

Elektronenemissionen und Farbzentren bei Ionenkristallen

Zusammenfassung Es werden weitere Erkenntnisse über die Elektronenemission aus verschiedenartig gefärbten Ionenkristallen angeführt und die näheren Zusammenhänge zwischen den Farbzentren und einigen physikalischen Erscheinungen besprochen, wie z. B. dem äusseren Photoeffekt, der Thermolumineszenz und der aktivierten Adsorption.     

Thermostimulated phenomena in the crystals NaCl doped with Mg

Optical and thermostimulated phenomena have been measured in differently irradiated crystals NaCl: Mg after different thermal treatment and bleaching in the F-band respectively. Similarly to the calcium doped crystals, the maxima of the thermostimulated luminescence (TL) were found. The maxima are situated in the region from 400 to 550 K too. New maxima were found in the region from 550 to 650 K in strongly irradiated samples. Absorption bands in the UV region have been tentatively attributed to the TL maxima. On the basis of these results we have tentatively proposed models of relevant colour centres and of recombination mechanism of TL with ions of Cu as luminescence centres.     

Absorption phenomena in multicomponent phosphate glasses with Mn

The absorption and ESR spectra of multicomponent alumino-phosphate glasses doped with manganese (0·2–20 mol %) has been measured and compared with the absorption spectra of manganous and manganic ions in model solutions. The unirradiated glasses show in ultraviolet region increasing absorption below 200 nm with the shoulder at 235 nm and the absorption bands due to manganous oxygen complexes in octahedral symmetry. They are similar to the absorption bands of Mn²⁺ in concentrated H₃PO₄ acid. In irradiated glasses the bands at 200, 235, 275 (only if Mn is present) and a broad band at 540 nm appear. After the annealing at 450 C all radiation-induced bands disappear and the bands at 235 nm is more pronounced. The Mn³⁺ in H₃PO₄ solution exhibit the absorption spectrum with a weak band at 530 nm and a very intense band at 270 nm. It is therefore proposed that both the 540 and 275 nm bands in irradiated glasses can be assigned to octahedral oxygen complexes of Mn³⁺, i.e. to hole centres. The band at 200 nm which is practically independent of the modifiers (Be, Mg, Ca, Sr and Ba) is, therefore, associated with electron centres (electrons trapped in non-bridging oxygen vacancies). It is suggested that the band at 235 nm in irradiated and annealed glasses is associated with irreversible structural changes.The authors wish to express their appreciation to H.Dvoáková for preparing the solutions and E.Linhartová for careful measurements.     

The absorption of cupric halides

Thin films of cupric halides were prepared and their absorption was measured in 185–3,500 nm spectral region. The interpretation of the absorption curves is given on the basis of electrond-d and charge transfer transitions in the prolonged octahedral halogenocupric complexes.     

Die Elektronenemission bei Röntgenbestrahlten Ferriten

Ohne Zusammenfassung