Color centers in mixed crystals of KCl-KBr: Mollwo-Ivey relationship

Several absorption bands (F, M, R₁, R₂, N₁) of color centers in mixed crystals of KCl-KBr are found to obey Mollwo-Ivey type relationships as the composition of the solid solution is varied.     

Studies on bombardment-enhanced conductivity. IV: IV. On the chemical state of oxygen-bombarded Nb2O5

It is now a well-established result that an increased oxygen content in bombarded metal targets influences the yields of secondary ions or photons. A similar influence appears to have been identified also for a decreased oxygen content in the case of bombarded oxide targets. The chemical state of targets which have gained or lost oxygen is less often specified and the present work was therefore undertaken to determine this state in a particular system, oxygen-bombarded Nb₂O₅. The results relate to conductivity, annealing, and electron diffraction. Specifically, intermediate doses $\text{(? 4 × 10}\text{ions}\text{cm}{}^2\text{)}$ of 35 keV oxygen ions led, as with many other substances, to amorphization with unchanged conductivity. Doses in excess of $\text{2 × 10}{}^{17}\text{ions}\text{cm}{}^2$, however, caused an increase in the bulk conductivity of a factor of about 4 × 10⁸ as well as a corresponding stoichiometry change such that Oxygen was lost and a thin layer of crystalline NbO was formed. These changes persisted when bombarded specimens were heated in vacuum at 150–800 °C. The results are discussed from the standpoint of three mechanisms, namely thermal-spike induced vaporization, internal precipitation, and preferential sputtering. Vaporization could be excluded on the basis of the oxygen partial pressures for the process $\text{Nb}{}_2\text{O}{}_5\text{(1) = 2}\text{NbO}\text{(1) +}\text{3}\text{2}\text{O}{}_2\text{(g)}$ being too low, while precipitation could be tentatively excluded on the basis of the vacuum annealings. There were no obvious objections, however, to a model for oxygen loss based on preferential oxygen sputtering even if the details of the model were unclear.     

Energies and relative intensities of Kα3 and Kα4 x‐ray satellites of sulfur and sulfides by photon excitation

Energies and relative intensities of the K x‐ray satellites K_α4 and K_α3 of sulfur and two sulfides K₂S and FeS are measured by a wavelength dispersive spectrometer. The energy shifts of these satellites relative to the diagram line are compared with Dirac–Fock theoretical values. The energy shifts and relative intensities are examined for chemical effects. Supplementing the present data to the available data, Z dependence of K_α4/K_α3 intensity ratio is studied in the low Z region. Copyright © 2007 John Wiley & Sons, Ltd.     

Bleaching of color centers in NaCl crystals with laser pulses

Abstract

Bleaching of F centers in gamma irradiated NaCl crystals at room temperature and elevated temperatures using laser pulses from pulsed laser systems is studied in this paper. The rate of decay of F centers is monitored and the decay constants are evaluated. A comparison on the decay kinetics is made for CW and pulsed bleaching with a He-Cd laser. F center to C center conversions using a thermo-optic scheme are carried out with nanosecond dye laser pulses in gamma irradiated NaCl crystals.     

Determination of traces of thallium in zinc and cadmium metals and process solutions by atomic-absorption spectrophotometry after extraction with di-isopropyl ether and reductive stripping

The bromo-complex of thallium(III) is extracted into di-isopropyl ether and reductively stripped into sodium sulphite solution, which is then analysed for thallium by atomic-absorption spectrophotometry. Thallium in zinc and cadmium metals and process solutions can be determined by this method.