Measurement of the K X-ray absorption jump factors and jump ratios of Gd, Dy, Ho and Er by attenuation of a Compton peak

The X-ray absorption jump factor and jump ratio of Gd, Dy, Ho and Er were measured with a Si(Li) detector by attenuation, with Gd, Dy, Ho and Er foil, a Compton peak produced by the scattering of the Am-241 Gamma rays. Al was chosen as secondary exciter. The experimental absorption jump factors and jump ratios are compared with the theoretical estimates of WinXcom (Radiat. Phys. Chem. 60 (2001) 23), McMaster (Compilation of X-ray cross sections UCRL-50174, 1969; Sec. II. Rev. I), Broll (X-ray Spectrom 15 (1986) 271), Hubbel and Seltzer (NISTIR (1995) 5632) and Budak (Radiat. Meas. accepted for publication). The present results constitute the first measurement for this combination of energy and elements, and good agreement is obtained between experiment and theory.     

On the use of Fourier-transformed Compton profile for the determination of band occupancies in certain solids

The Pattison-Williams method of using Fourier-transformed Compton profiles for obtaining Fermi momenta in simple metals, is extended to set up a scheme for inferringd orf band occupancies in transition metals, rare earths etc. CP measurements are reported for Ni,α-Mn andβ-Mn and then the new scheme is applied to obtain 3d occupancies in these systems. Some comments on the use of this method for other systems are also made.     

On a low intensity <Superscript>241</Superscript>Am Compton spectrometer for measurement of electron momentum density

In this paper, a new design and construction of a low intensity (100 mCi) ²⁴¹Am γ-ray Compton spectrometer is presented. The planar spectrometer is based on a small disc source with the shortest geometry. Measurement of the momentum density of polycrystalline Al is used to evaluate the performance of the new design. The measured profile is in good agreement with the existing theoretical data and our density functional calculations.      

Measurement of the K shell X-ray production cross-sections and fluorescence yields for Nd,Eu, Gd,Dy and Ho using radioisotope X-ray fluorescence in the external magnetic field

The effect of external magnetic field on the K_α and K_β X-ray production cross-sections and K shell fluorescence yields for ferromagnetic elements Nd, Gd and Dy and paramagnetic elements Eu and Ho have been measured at the excitation energy of 59.5 keV γ -rays from ²⁴¹Am radioactive source of strength 100 mCi in the external magnetic field of intensities ±0.75 T. Furthermore, I_Kβ /I_Kα intensity ratios for these elements have been measured in the external magnetic field. The K X-rays from different targets were detected using a high resolution Si(Li) semiconductor detector. For B = 0, the measured K X-ray production cross-sections, K shell fluorescence yields and the I_Kβ /I_Kα intensity ratios were compared with the experimental and theoretical data in literature. The results have shown that the fluorescence parameters as photoionization cross section, fluorescence yield, radiation rates and spectral linewidth can change when the irradiation is conducted in a magnetic field.     

EXAFS study of intermetallics of the type RGe2 (R=La,Ce, Pr,Nd, Sm,Gd, Tb,Dy, Ho,Er and Y) Part II: Determination of Ge-R distances

The extended x-ray absorption fine structure (EXAFS) associated with the GeK x-ray absorption discontinuity in pure germanium and in the intermetallics RGe₂ (R=La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y) has been studied. The Ge-R distances in these compounds have been determined by comparing the experimental phase shifts with the theoretical ones. The Ge-R distances in the compounds TbGe₂, HoGe₂ and ErGe₂ are being reported for the first time in this work.     

EXAFS study of intermetallics of the type RGe2 (R=La,Ce, Pr,Nd, Sm,Gd, Tb,Dy, Ho,Er and Y) Part I: Determination of Ge-Ge distances

A study of theEXAFS associated with theK x-ray absorption discontinuity of germanium in pure germanium and in the rare-earth germanides RGe₂ (where R=La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Y) has been carried out. The Ge-Ge distances have been obtained in these compounds. Considering the phase to the RGe₂ system, the bond lengths in these compounds have been determined. The values obtained by us for the RGe₂ compounds (R=La, Ce, Pr, Nd, Sm, Gd, Dy and Y) agree with those obtained earlier by crystallographic methods. The bond lengths for the compounds TbGe₂, HoGe₂ and ErGe₂ are also being reported.     

Sum peak method applied to the study of decay of Ir-192

The electron capture probabilities to 690.70 and 580.37 keV levels and theK-conversion coefficients of 205.9 and 316.5 keV transitions in the decay of Ir-192 have been determined from the measurement of gamma-ray intensities in conjunction with an analysis of theKX-ray-γ-ray sum peaks observed with a co-axial HPGe detector. TheK-capture probability to 690.70 keV level was determined by an approach which is independent ofK-shell fluorescence yield and absolute detection efficiency forKX-rays. TheK-shell fluorescence yields of the daughter products, namely, Os and Pt of Ir-192 have also been determined by the same technique and were found to be 0.964±0.077 and 0.969±0.068 respectively.     

Synthesis,structure and luminescence properties of a series of dinuclear LnIII complexes (Ln=Gd,Tb, Dy,Ho, Er)

The reactions of lanthanide nitrates with a Schiff-base ligand HL (2-[(2-hydroxypropylimino)methyl] phenol) have produced five new complexes with formula as [Ln₂(L)₃(NO₃)₃]CH₃OH(Ln=Gd 1, Tb 2, Dy 3, Ho 4, Er 5). These new complexes are characterized by elemental analysis, IR and X-ray diffraction, as well as fluorescence spectra. Single-crystal X-ray diffraction analysis reveals that all the complexes crystallize in the trigonal system, space group R-3. Fluorescence spectroscopy of Tb(III) and Dy(III) complexes display strong characteristic metal-centered fluorescence in solid state, which demonstrates that luminescence is sensitized by the effective energy-transfer from ligand to the metals. The fluorescence lifetimes of complex 2 and 3 are also determined.     

Mechanisms of K Mixing: the Role of Octupole Vibrations in 180Ta

K-mixing mechanisms are reviewed, with reference to isomers in the A≈180 region of well deformed nuclei. The strong E1 photoactivation of ¹⁸⁰Ta ^m , through states at 1.1, 1.3 and 1.5 MeV, provides evidence for the role of octupole vibrations in the conversion of the K = 9 isomer to the K = 1 ground state. This revised version was published online in August 2006 with corrections to the Cover Date.     

X-ray study of the low-temperature phase transition in K2CoCl4

Precise lattice parameter measurements and intensity measurements of selected main and satellite reflections of K₂CoCl₄ have been performed in the temperature range 100 to 300 K in the vicinity of the low-temperature phase transition (commensurate-commensurate phase transition, T _c = 142 K). A broadening of the FWHM for the h01 reflections was observed below 142 K which suggests a transition from an orthorhombic phase to a monoclinic phase.     

Ultraviolet upconversion luminescence of Gd from Ho and Gd codoped oxide ceramic induced by 532-nm CW laser excitation

Ultraviolet upconversion emissions around 314 nm from ⁶P_J states of Gd³⁺ ions have been observed in Y_1.98 − xGd_xHo_0.02O₃ (x = 0.02, 0.10, 0.20, and 0.30) oxide ceramics under the excitation of a continuous-wave 532-nm laser. We found that the energy transfer process from Ho³⁺ to Gd³⁺ plays an important role in populating the ⁶P_J states of Gd³⁺. The doping of Gd³⁺ ions does not affect ⁵G₄ and ⁵G₅ states but only the ³D₃ state of Ho³⁺. The emissions from ³D₃ state decrease with the increase of Gd³⁺ concentration. Power dependence curves and time-resolved spectra have been measured to identify the proposed upconversion mechanism.     

Relation between the intensity of ir absorption bands of stretching vibrations of nitrogroups and their number in aromatic nitrocompounds

Yaroslavl' State University, 9 Matrosov Ave., Yaroslavl', 150023, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 6, pp. 30–37, November–December, 1995.     

Defect annealing in the hexagonal close packed heavy rare earth metals Gd,Tb, Dy,Ho, Er,Tm and Lu after electron irradiation at low temperatures

The recovery spectra of the heavy rare earths Gd, Tb, Dy, Ho, Er and Tm were determined after irradiation with electrons at low temperatures. In the cases of Er and Tm, strong thermal cycling phenomena were observed and attributed to hydrogen atoms changing configurations and interacting with the magnetic structure of the metal. After elimination of these effects in Er and Tm, all the spectra—together with those of the earlier treated Lu—had rather similar form: several close-pair peaks followed by a broad complex substage resembling the stage I _D in f.c.c metals and attributed to long-range interstitial migration. A correlation is found between the temperature of the maximum of this substage (normalized to the melting temperature) and the c/a-ratio of the metals.     

Muon transfer from excited states of muonic hydrogen atoms studied by X-ray measurement

Muon transfer from proton to deuteron was examined with muonic X-rays. The parameter q _1s was determined directly and the time spectra of the X-rays were analyzed for effects of the muon transfer reaction. This revised version was published online in August 2006 with corrections to the Cover Date.