Local31P and distant31P and195Pt ENDOR studies of powdered samples of Bis(O,O′-disubstituted-dithiophosphato)copper(II) complexes magnetically diluted in the corresponding Pd(II) and Pt(II) host lattices

ENDOR studies on bis(dithiophosphato)copper(II) complexes magnetically diluted in the corresponding Pd(II) and Pt(II) host lattices performed with the use of the method of “polycrystalline ENDOR crystallography” are reported. In these samples well resolved local³¹P (A_iso ca. 29 MHz and A_aniso ca. 0.9 MHz) as wel1 as distant³¹P (A _iso ca. 1.3 and 5.5 MHz and A_aniso ca. 0.2 and 0.4 MHz) and¹⁹⁵Pt (A_iso ca. 3.1 MHz and A_aniso ca. 0.2 MHz) ENDOR transitions are recorded. It is shown that the directions of the main values of A_aniso for all local³¹P and distant³¹P and¹⁹⁵Pt ENDOR transitions are parallel. Comparison of these results with those reported about the same complexes but diluted in other host lattices shows that there is no difference in the EPR and local³¹P ENDOR parameters thus suggesting that the structure of the paramagnetic complex remains unchanged. It is found that distant ENDOR transitions appear only in the case when the host lattice contains one molecule in the unit cell, i.e., when all molecules are parallel to each other. Using the obtained data from local and distant³¹P ENDOR transitions some structural features of Cu(dtp)₂ as well as Pd(dtp)₂ and Pt(dtp)₂ complexes are found for the first time.     

TheK-shell conversion coefficient of the 135.5 keVM4 transition in193m Pt decay

TheK conversion coefficient of the 135.5 keVM4 transition in^193m pt has been determined by the XPG method. The result isα _K =135.2±10.5 and the value exhibits a deviation 3.4% below the theoretical prediction of Hager and Seltzer. Similar deviations have been systematically observed in precision values ofE3 andM4 conversion coefficients reported in the literature.     

Mean lifetimes of excited levels of Ar II. I. Time correlation measurements

Mean Lifetimes of excited levels of Ar II have been measured using the method of time-correlated photons in cascade. The following results were obtained: for 4p⁴S^°_{$\text{3}\text{2}$}, τ = 7·2±0·3ns; for 4p′²F^°_{$\text{7}\text{2}$}, τ = 8·8±0·2 ns; for 4p′²F^°_{$\text{5}\text{2}$}, τ = 8·0±0·2 ns. These results are compared with experimental and theoretical values.     

Excited states in195Pt from the decay of 2.3h195Irg, 3.7h195Ir m and 183d195Au

The decay of two previously reported isomers in¹⁹⁵Ir has been investigated with Ge(Li) and Si(Li) detectors by observing β and γ rays as well as conversion electrons in single and coincidence measurements. To about 30 of the 85 observed transitions a multipolarity was assigned. The energies of the gamma rays from¹⁹⁵Au were also determined accurately. The decay scheme of¹⁹⁵Ir shows 13 new levels in¹⁹⁵Pt between 389 and 931 keV. Probable spin and parity assignments could be made to most levels. The results are compared with those of a recent Coulomb excitation study, reaction work and theoretical calculations.     

The conversion electron spectrum in the decay of195Au

Twenty-four internal conversion lines in the decay of¹⁹⁵Au have been studied at high resolution by means of the Vanderbilt iron-free spectrometer. The electron intensities of this work and previously published photon intensities were used to calculate the percentage decay to each level in¹⁹⁵Pt. Conversion coefficients andL subshell ratios were used to assign the following multipolarities: 30.8 keV, pureM1; 98.8 keV, (99±1)%M1; 129.8 keV, pureE2; and 210 keV, pureE2. MeasuredL subshell ratios are not in good agreement with theoretical values.     

Internal conversion of valence shell electrons: Measurement and analysis for the 10.84 keV transition in206Bi

Conversion electrons of the 10.84 keV transition in²⁰⁶Bi were measured with the iron-free magnetic spectrometer. The conversion line of the valence shell was observed to be narrower than those of the inner ones. The computer program which optimizes the line profiles given numerically is outlined and used for the spectrum analysis. The studied transition was proved to be pure M1 with the nuclear structure parameterλ=1.7±0.7. The internal conversion coefficients were calculated using the relativistic Hartree-Fock model for neutral atoms as well as various isolated ions. Altogether, 15 different valence-shell configurations were considered. The prediction for the 6s ₁ ^2/2 configuration (Bi³⁺) is in accord with the measured conversion intensities. This is consistent with probable chemical form Bi₂O₃ of bismuth atoms in the radioactive source.     

Nuclear magnetic resonance study of 31P and 195Pt in the metallic glass system (NixPt1−x)75P25

Measurements of the ³¹P and ¹⁹⁵Pt nuclear magnetic resonance are reported for metallic glasses of the composition (Ni_xPt_1?x)₇₅P₂₅, where x = 0.20, 0.30, 0.40, 0.50, 0.60, 0.64 and 0.68. Spectra were obtained at room temperature, for frequencies from 4 to 16 MHz. The results provide support for certain aspects of the “dense random packing” structure and a transfer of charge from the metalloid to the transition metal atoms.     

Directional correlation studies in the decay of177gLu

Directional gamma-gamma correlations of the strong 208.4–112.9 keV and of the weak 71.6–249.7 keV cascade transitions in the decay of^177gLu have been measured. The correlation coefficientsA ₂₂=?0.208±0.012 of the strong andA ₂₂=?0.105±0.005 of the weak cascade have been determined. The mixing ratioE2/M1 of ?3.7±0.3 for the 112.9 keV transition and theM2/E1 of ?0.0173±0.0065 for the 71.6 keV transition have been obtained. The deducedM2 admixture in the 71.6 keV transition is in good agreement with the theoretical estimates of Weisskopf and of Nilsson.

     

Direct measurements of the dynamical correlation length indicate its divergence at an athermal glass transition

The supercooled N3 model exhibits an increasingly slow dynamics as density approaches the random closest packing density. Here, we present a direct measurement of the dynamical correlation function G4(r,t), showing the emergence of a growing length scale ξ(4) across which the dynamics is correlated. The correlation length measured, up to 120 lattice sites, power law diverges as the density approaches ρ(t), the density at which the fluid phase of the model is predicted to terminate. The four-point susceptibility, often used as an agent to estimate ξ(4), does not depend simply on the latter. Rather, it depends strongly on the short-range behavior of G4(r,t). Consequently, χ(4) peaks before ξ(4) reaches its maximal value. The two quantities should therefore be studied independently.     

Determination of the parity of the 305 keV state of 48V by linear polarization correlation measurements

The linear polarization correlation of the (116–305) keV γγ cascade in the decay of ⁴⁸Cr has been investigated by means of a multidetector apparatus. In two different runs, we measured the polarization of the 305 keV radiation as well as that of the 116 keV radiation. Positive parity was derived for the 305 keV state, and the measured coefficients confirm this result. The measurements also give multipolarity assignments of the if γ-rays involved.     

Spin-echo measurements of the conduction electrons self-diffusion coefficient in a metal

The principle possibility of spin echo measurements of conduction electron orbital motion parameters is experimentally demonstrated, using metallic lithium as an example.     

PAC measurements of the Verwey transition in magnetite

Hyperfine Interactions - Perturbed angular correlation (PAC) experiments with implanted 111In tracers have recently been used to investigate magnetic phase transitions in metal oxides. Here we...     

The correlation splitting of the energy levels of electrons in a crystal

The symmetry groups for the model of a space of singly occupied states are considered, and their representations in this space are found. The correlation splittings of the energy levels for electrons in k-space are considered on this basis. The time reversal operation is allowed for.     

Internal conversion of the 6.2 keV transition in181Ta

The total conversion coefficient of the 6.2 keV Mössbauer transition in¹⁸¹Ta was measured by X- and gamma-ray spectroscopy. The result of 86 ± 20 disagrees with the literature value of 46, but agrees with theory if a nuclear penetration parameter deduced from relative conversion electron intensities is taken into account. The weak 6.2 keV gamma ray has intensity per decay that is less than the previous value by a factor of 8.5.     

Nuclearg-factors of the 328 keV state in194Pt,the 240 keV state in195Pt,and the 356 keV state in196Pt determined by recoil-implantation into iron and cobalt hosts

The iron-implantation-perturbed-angular-correlation technique (IMPACT) has been used to measure the Larmor precessions of the 328, 240, and 356 keV states of¹⁹⁴Pt,¹⁹⁵Pt, and¹⁹⁶Pt nuclei, respectively, in ferromagnetic iron and cobalt hosts. The observed angular precessions in iron, corrected for the transient field effect, wereω τ ₁₉₄(328)=0.103±0.006 rad,ω τ ₁₉₅ (240)=0.142±0.012, andω τ ₁₉₆(356)=0.084±0.010. For cobalt hosts, the observed Larmor precessions were ω τ₁₉₄(328)=0.068±0.006, ω τ₁₉₅(240)=0.096±0.012, andω τ ₁₉₆(356)=0.057±0.013. Agreement between theg-factors obtained from the measurements in iron hosts and the measurements in cobalt hosts is very good, and a weighted average of the two measurements givesg ₁₉₄(328)=0.349±0.031,g ₁₉₅ (240)=0.136±0.013, andg ₁₉₆(356)=0.329±0.039.     

Oscillator strengths of ultraviolet V(II) lines from measurements in a vanadium-helium plasma

A V-He plasma has been produced in a well-stabilized arc. Oscillator strengths for 66 V(II) lines in the range 2342–2617 Å have been determined. Comparisons with theoretical values show large discrepancies for about 25% of the lines, possibly due to errors in calculations and in term classifications.     

Internal conversion studies of the 114 keV transition in175Lu

Measurements of the conversion line intensities, the directional correlation and the conversion probability for the 114 keVM1+E2 transition in¹⁷⁵Lu are reported. TheE2 admixture, determined from relativeK andL intensities, is (19.2±0.2)%. The theoreticalL _I internal conversion coefficient is found to be about 8% too low relative theK,L _II andL _III conversion coefficients.     

Transition energies of ND4Cl and ND4Br in the transition I⇄II

The energy of the transition I?II of ND₄Cl and ND₄Br was measured by using a direct differential calorimetric method. The results 1024 cal/mole for ND₄Cl and 847 cal/mole for ND₄Br were obtained. The accuracy was estimated to be about 2%. The approximate transition temperatures 169°C for ND₄Cl and 118°C for ND₄Br were observed.