Electron Spin Resonance of Cu2+ Ion in CdWO4, ZnWO4, and MgWO4 Single Crystals

Abstract

3078WELLMAN, DEWITT, AND ELLIS ideal fused-salt mixtures. In the latter case, in particular, the changes in kinematic viscosity with temperature and composition make it necessary to use the newly developed calculation. CONCLUSIONIn conclusion, the kinetic-energy correction factor does not vary with kinematic viscosity or flow rate in the range corresponding to Re from 50 to 1500. (At high flow rates, with an appreciable change in hydrostatic head during a determination, the maximum rather than average flow rate should be used to calculate the Re.) For precise work, the correction factor must be determined for each capillary whether it has trumpet-shaped or square-cut ends. In the construction of a viscometer, especially when the material is glass, it is often convenient to make the capillary with trumpet-shaped ends, in which case the geometric constants must be determined by calibration. For absolute viscosity determinations, the capillary should have square-cut ends to allow a reliable determination of the effective length.Some recent work with square-cut capillaries,32 used 32 G. P. Flynn, R. V. Hanks, N. A. Lemaire, and J. Ross, J. Chern. Phys. 38, 154 (1963). THE JOURNAL OF CHEMICAL PHYSICSin the determination of the viscosity of dense gases, was called to our attention by the referee for this paper.In that work, m was found to be constant over a wide range of kinematic viscosities and Reynolds numbers but deviated from the constant value at Re greater than 1600. This is entirely in agreement with our results since, under the conditions employed, there was no necessity for the hydrostatic-head calculation.In viscometers in which all or part of the driving force is a varying hydrostatic head, it is necessary to use a calculation which includes a correction for the interaction of the hydrostatic-head and kinetic-energy effects. The more complicated calculation is especially important where the kinematic viscosities of the calibration and test materials are greatly different.Although the exact equations, with the combined hydrostatic-head and KE corrections, are complex and require solution by a series of approximations, the need for more accurate viscosity data indicates a need for more work along this line. The accessibility of computers eliminates, to a large extent, the need for using approximate solutions to simplify the calculations. We plan to continue this work to develop exact expressions for other reservoir configurations and methods for handling the calculations more efficiently.Paramagnetic resonance measurements have been carried out at 78 0 and at 4°K on Cu2+ ions diluted in single crystals of CdW04, ZnW04, and MgW04• The g factors and the hyperfine interaction with the copper nucleus have been determined. From this experimental data the ground-state wavefunction of the Cu 2 + ion has been constructed. It has also been possible to calculate the relevant 1=2 terms of the low-symmetry crystal-field components. Then in the framework of a simple g-factor theory the g-factor anisotropy has been calcula...

EPR and optical absorption studies of Cu2+ ions doped magnesium citrate decahydrate single crystals

“…The ground state wave function in such crystals has been determined by the formula˛|x 2 − y 2 +ˇ|3x 2 − r 2 [20], where˛is very near to unity andˇis very less than unity. By using the theory of Bleaney et al [21] several workers [22,23] have studied the ground state wave function of Cu 2+ ion in different lattices. A similar procedure has been adopted in the present study.…”

Investigation of Cu-doped Li2B4O7single crystals by electron paramagnetic resonance and time-resolved optical spectroscopy

“…The Cu + ion is the most probable candidate for the emitting centre in Li 2 B 4 O 7 :Cu. Accordingly, its 3d 9 4s → 3d 10 transitions have been considered to be responsible for the 3.35 eV emission band [7,8]. The peaks in the absorption spectrum of the Li 2 B 4 O 7 :Cu crystal mostly correspond to the bands observed in the excitation spectrum and are also related to the Cu + charge state of the dopant.…”

Electron spin resonance investigation of undoped and Li‐doped CdWO4 scintillator crystals

“…Due to the equality of the Cd 2+ and Mn 2+ ionic charges it is expected that Mn impurity sits at the Cd site. This is also supported by the fact that the magnetic axes of both Mn 2+ and Fe 3+ as well as of Cu 2+ [4] have approximately the same orientation with respect to the crystal axes, and these directions agree 6 As both the undoped and Li doped crystals were grown from the same row materials we assume that the crystals contained both the Fe and Mn impurities. In the undoped crystal Fe was in the 3+ charge state and therefore it was visible in EPR.…”

“…Its applications mainly focus on the detection of X-rays and γ-rays in medical field [1]. As concerns the density and light yield CdWO 4 is superior comparing to other scintillating materials. On the other hand, its practical importance is seriously limited by relatively slow scintillation response.…”