Monte-Carlo calculation for the classical F.C.C. Heisenberg ferromagnet

The equilibrium properties of the classical f.c.c. Heisenberg ferromagnet are studied by Monte- Carlo techniques for small finite systems. Using the asymptotic dependence on the system size the results are extrapolated to the infinite system. The critical temperature is found to be T_c = 3.18 ± 0.02 and the critical exponents obtained are β = 0.33 ± 0.02, γ = 1.37 ± 0.04. The specific heat appears to have a cusp with α′_s = 0.1 ± 0.03 and α_s = 0.1 ± 0.1. Remarkable agreement is found with the finite-scaling theory.     

The effect of a weak magnetic field on the mobility of dislocations in silicon

The magnetoplastic effect in dislocation silicon is discovered. It is shown that in the presence of tensile stresses (up to 20 MPa), the mechanically activated path of surface dislocation half-loops is limited mainly by the dynamics of defects in various slip systems relative to the applied load. The activation barriers for the motion of dislocations controlled by various conditions in the temperature range T=850–950 K are E _aF=2.1±0.1 eV and E _aS=1.8±0.1 eV. An increase in the path of surface dislocation half-loops and a change in the activation barriers are detected (E _aF=1.4±0.1 eV and E _aS=1.6±0.1 eV) after subjecting silicon to a magnetic field (B=0.7 T) for 30 min. Possible reasons behind the observed effects are discussed.     

Konversionskoeffizienten und Fluoreszenzausbeuten beim Zerfall des Hg199m

Hg^199m was produced by bombarding natural HgO with fast neutrons. The conversion electrons of the cascade decay were investigated with Si(Li)-counters. By application of the summing technique the conversion coefficients andL-shell fluorescence yields of Hg were determined. The gamma rays were studied with a Ge(Li)-counter. The following results were obtained: half-lifeT _1/2=(42.6± 0.2) min; energies of the transitionsE _γ1=(374.1± 0.1) keV,E _γ1=(158.3± 0.1)keV; intensity ratio of the gamma raysI _γ(158 keV):I _γ(374keV)=(424± 42):100; conversion coefficients α_K158=0.30± 0.03, α_total158=0.94± 0.09, α_K158/α_LM...158=0.47± 0.02, α_L158/α_M...158=3.10± 0.16;α_K374=3.51± 0.28,α_total1374=6.19±0.47,α_K374/α_LM...374=1.32±0.04, α_L374/α_M...374=2.14±0.11;L-shell fluorescence yields \(\bar \omega _L \) =0.40± 0.04, ω_KL=0.41±0.04.     

Half-lives andP n values of delayed-neutron precursors in the mass chains 85–87, 92, 135, 136 and 145

Further results are presented on half-lives and neutron emission probabilities (P _n ) of short-lived delayed-neutron precursors in the mass chains 85–87, 92, 135, 136 and 145 obtained with the recoil focussing parabola-type mass separator for unslowed fission products LOHENGRIN installed at the Grenoble high-flux reactor. A newP _n -value of (44±14)% is given for the (0.73±0.06)s⁸⁷As; theP _n -values of seven precursor nuclides have been redetermined: (1.9±0.1)s⁸⁵As with (22±8)%, 0.9s⁸⁶As with (10.5±2.2)%, (0.35±0.04)s⁹²Br with (21±8)%, (1.6±0.15)s¹³⁵Sb with (14±1)%, (0.9±0.1)s¹³⁶Sb with (19±9)%, (17.5±0.2)s¹³⁶Te with (2.0±1.0)% and 0.6s¹⁴⁵Cs with (12.5±3.0)%. The results are compared with the existing data, and the neutron emission probabilities are discussed within a simple semi-empirical picture.     

Pressure effects on the magnetic transition temperatures of NiS2

Both antiferromagnetic (T_N) and weak ferromagnetic (T_c) transition temperatures of NiS₂ have been measured under pressure up to 18.4 kbar. Values of dT_N/dP=(0.9 ± 0.1) deg/kbar and dT_c/dP=(0.4 ± 0.1) deg/kbar are obtained. The present results allow estimates of the magnetic Grüneisen constant γ_m = - d ln T_N/d ln V of (26±5) and of the entropy change of (1.4±0.5) J/mol·deg at the first order transition temperature T_c.     

Mössbauer study of Er3+ in ErH3 and YH3

The Mössbauer spectra of ¹⁶⁶Er in ErH₃ and YH₃ have been measured. Using and axial Hamiltonian, the electronic gyromagnetic rations for the ground state of Er³⁺ in YH₃ have been deduced: g| = 11.6 ± 0.1 and g⊥ = 4.4 ± 0.1. The analysis yields crystal field parameters which provide the correct λ₇ ground state with these g-values.     

Exciton spatial dispersion determined through the two-photon Raman scattering via excitonic molecule state at large wave vectors in CuCl

With simultaneous excitation of two dye laser beams the Raman scattering is studied in which the intermediate state is the excitonic molecule and the final states are the longitudinal and transverse excitons. The L-T splitting shows a large k-dependence. The effective masses are determined to be (2.3 ± 0.1)m₀ and (3.1 ± 0.1)m₀ for the transverse and longitudinal excitons, respectively.     

Copper ion induced reactions on110-108-106Cd,109-107Ag and110Pd. new rhenium,osmium and iridium isotopes

By⁶³Cu induced reactions on¹¹⁰Cd,¹⁰⁸Cd,¹⁰⁶Cd,¹⁰⁹Ag,¹⁰⁷Ag and¹¹⁰Pd targets, new isotopes were searched in the Ir, Os, Re region. Cross bombardments and excitation function measurements were used to identify newα emitting isotopes:¹⁷⁰Ir (E _α = 6.01 ±0.01 MeV?T _1/2=1.1±0.2s),¹⁶⁹Ir (E _α =6.11±0.01 MeV?T _1/2=0.4±0.1 s),¹⁶⁸Ir (E _α =6.22±0.02 MeV,¹⁶⁸Os (E _α =5.66±0.01 MeV?T _1/2=1.9±0.1 s),¹⁶⁷Os (E _α =5.84 ±0.01MeV ?T ^1/2=0.65±0.15s),¹⁶⁶Os (E _α =6.00±0.02 MeV?T _1/2=0.3 ±0.1 s),¹⁶⁵Os (E _α =6.20±0.02 MeV),¹⁶⁹Re (E _α =5.05±0.01 MeV),¹⁶⁸Re (5.26±0.01 MeV?T ^1/2=5.5 ±0.5 s). Theα-decay measurements are compared to theQ _α values obtained from different mass predictions.     

Magneto-optic study of the critical region of EuS

Critical exponents of the insulating ferromagnet europium sulfide are determined using the technique of Faraday rotation. Values obtained are γ = 1.06 ± 0.05, β = 0.335 ± 0.01, δ = 4.20 ± 0.1 and T_c = 16.52 ± 0.02 K. The data are found consistent with the scaling hypothesis.     

Orientational and positional disorder of ions and its freezing in the CsNO2-TlNO2 system2

The heat capacities of Cs_0.695Tl_0.305NO₂ (Specimen I) and Cs_0.385Tl_0.615NO₂ (Specimen II) have been measured between 14 and 350 K. Specimen I underwent a phase transition at (197.7 ± 0.1) K, with ΔS = (19.2 ± 1.5) JK^?mol^?, and specimen II at (214.5 ± 0.2) K, with ΔS = (5.4 ± 1.0) JK^?1mol^?1, respectively. Above the phase transition, an exothermic temperature drift due to phase separation was observed. Annealing of the sample at 203 K for 300 hr brought about complete phase separation. The solid solution system annealed at 203 K gave two heat capacity peaks at (203.3 ± 0.1) K, with ΔS = (13.8 ± 0.8) JK^?1 mol^?1, and (242.4 ± 0.2) K, with ΔS = (10.6 ± 1.3) JK^?1 for Specimen I, and at (203.0 ± 0.1) K with ΔS = (6.7 ± 0.5) JK^?1 mol^?1, and (257.5 ± 0.2) K with ΔS = (17.9 ± 1.7) JK^?1 mol^?1 for Specimen II. The phase diagram of the CsNO₂-TlNO₂ binary system was constructed on the basis of DTA, heat capacity and dielectric measurements. In the metastable phase, the existence of a residual entropy due to the freezing of a random distribution of Cs⁺₁ and Tl⁺ cations in addition to the orientational disorder of the NO₂^?1 ion was confirmed by a comparison of entropies of the stable and the metastable phases.     

Microwave spectrum and substitution structure of methylene chloride

The microwave spectrum of methylene chloride has been reinvestigated in order to obtain a complete substitution (r_s) structure of well-defined precision. Measurements on the ¹³CH₂Cl₂ species have yielded the following rigid-rotor rotational constants: A = 30746.20 ± 0.10 MHz, B = 3320.63 ± 0.11 MHz, and C = 3053.44 ± 0.10 MHz. These data, combined with revised values reported earlier for other isotopic species, yields the following r_s structural parameters: CCl = 1.767 ± 0.002 Å, CH = 1.085 ± 0.002 Å, ∠HCH = 112.1 ± 0.2°, and ∠ClCCl = 112.2 ± 0.1°.     

Electronic structure of arsabenzene: Microwave spectrum,dipole moment,and nuclear quadrupole coupling constants

The microwave spectrum of arsabenzene was analyzed; a dipole transitions were observed. The following rotational constants were obtained; A = 4871.03 ± 0.18 MHz, B = 2295.87 ± 0.01 MHz, C = 1560.10 ± 0.01 MHz. The dipole moment was 1.10 ± 0.04 D. The nuclear quadrupole coupling constants due to the ⁷⁵As nucleus were χ_aa = ?186.4 ± 0.1 MHz, χ_bb = 43.5 ± 0.2 MHz, χ_cc = 142.9 ± 0.2 MHz, and the asymmetry parameter, η = 0.533 ± 0.002. Analysis of the quadrupole coupling constants indicated that the population of the 4p orbitals on arsenic decrease in the order n_a > n_b > n_c.     

The scattering of slow neutrons by phosphorus and nitrogen

The coherent scattering lengthsb and the free cross sections for the scattering of slow neutrons by P and N were measured on powdered samples. From the results we derived data for the incoherent cross sections and for the spin state scattering lengths. We found for phosphorus:b=5.13±0.01 fm, σ_free=3.134±0.010b and σ_inc=0.006±0.016b, and for nitrogen:b=9.36±0.02 fm, σ_free=10.03 ±0.08 b and σ_inc=0.4±0.1 b. Derived values for resonance parameters of N are given.     

High resolution measurements of the line positions and strengths of the 2ν2 band of H2CO

Spectra of the 2ν₂ band of formaldehyde have been obtained with high resolution (0.035 cm^?1). Measurements were made with path lengths of 8, 16, and 24 m and at sample pressures from 0.1 to 0.3 mm Hg at room temperature (～296°K). From these data, the following constants were determined for the 2ν₂ band in wavenumber units: v₀=3471.718±0.004,A=9.3958±030013,B=1.28100±0.00024,C=1.11662±0.00024, Tbbb=-12.8±0.5×10^-6,Taabb=60±5×10^-6. The line strengths were also obtained from the data. The strengths were analyzed to determine the band strength and the rotational factors. At 296°K, the strength of the 2ν₂ band was found to be 15.5 ± 0.9 cm^?1/(cm·atm).     

Investigation of the low lying levels in9B

The reaction¹⁰B(³He, α)⁹B(p)⁸Be(g.s.) has been studied using a 1.8 MeV³He⁺ beam. Coincidence spectra were measured at θ_α=?150? and θ_α=22.5?, 30?, 37.5?, 45?, 52.5?, 60? and 67.5? for the indentification of the levels in⁹B which decay by proton emission. Possible new excited levels in⁹B were observed at (1.9±0.1), (2.1±0.1), (2.6±0.1) and (3.1±0.1) MeV.     

Anisotropic polariton dispersion in red HgI2

We have measured resonant Brillouin Scattering near the A-exciton region of a layer-semiconductor, red-HgI₂. The Brillouin shift is interpreted in terms of a scattering process between the two polariton states by an acoustic phonon. The estimated exciton masses for the translational motion are (0.68 ± 0.1)m₀ and (1.2 ± 0.1)m₀ for the (100 and (001) directions, respectively.     

High performance organic planar heterojunction solar cells by controlling the molecular orientation

A highly efficient planar heterojunction OSC based on zinc phthalocyanine (ZnPc)/fullerene (C₆₀) by controlling the orientation of the ZnPc by using copper iodide (CuI) as the interfacial layer is reported. The proportion of face-on ZnPc molecules was increased significantly on the CuI layer compared to the layer without the CuI layer, which was analyzed with wide-angle X-ray scattering (WAXS) and optical absorption. The power conversion efficiency (PCE) of the orientation controlled planar heterojunction OSC was remarkably enhanced to 3.2 ± 0.1% compared with 1.2 ± 0.1% of the conventional OSCs without the control of the molecular orientation. By inserting the 3-nm-thick CuI layer, J_SC, V_OC and FF have increased from 4.6 ± 0.2 to 8.9 ± 0.2 mA cm^?2, from 0.48 ± 0.01 to 0.59 ± 0.02 V, and from 0.56 ± 0.01 to 0.61 ± 0.02, respectively. V_OC enhancement is discussed with the result of the ultraviolet photoemission spectra (UPS) measurements.     

Decay studies of131Ba

Bombarding a⁸⁵Rb target by 27 MeVα-particles the following half-lives of excited states in different nuclei have been determined by means of the generalized controid shift method: in⁸⁷Y,T _1/2(2827.1 keV)=0.75±0.10 ns,T _1/2(2675.9 keV)=0.25±0.10 ns,T _1/2(3595.3 keV)=0.5±0.2 ns andT _1/2(2986.9, 3094.4 keV)<0.1 ns; in⁸⁸Y,T _1/2(232.1 keV)=0.8±0.1 ns and in⁸⁵Rb,T _1/2(151.2 keV)=0.6±0.1 ns. In⁸⁷Y, the members of the doublet (vg ₉ ^2/?2 )₈₊ (πp_1/2) are identified. E2 transition rates 21/2⁺? 17/2⁺ in odd A≈ 90 nuclei are shown to represent essentially core transitions. Evidence for the existence of seniority-five configurations is found.     

The electron capture decay of125I and145Pm

The productP _K ω _K of theK-capture probability and theK-fluorescence yieldω _K was measured in the EC decay of 17.7 y¹⁴⁵Pm and 60.14d¹²⁵I by means ofK x-ray-γ-ray coincidences with semiconductor detectors. Accepting a best value ofω _K =0.920 forZ=60 from the literature, values ofP _K =0.606±0.025 and 0.554±0.025 for decay of¹⁴⁵Pm to the 67.2 and 72.4 keV levels in¹⁴⁵Nd, respectively, were determined, from which the application of EC theory givesQ _EC=153±4 keV to the ground state. TheP _K ω _K ratio to the 67.2 and 72.4 keV levels also was determined independently to be 1.11±0.01, which serves as a good check on theγ-ray-gatedP _K values. Theγ-ray energies were determined more accurately to be 72.4±0.1 and 67.2±0.1 keV, together with a ratio of their relative intensities,I _72.4/I _67.2=3.35±0.09. In the decay of¹²⁵I, a value ofP _K ω _K =0.699±0.030 was measured, and by using an independent determination ofQ _EC=178±2 keV to the ground-state from the literature, a value ofP _K=0.801 is calculated from allowed EC theory, from whichω _K =0.873±0.017 atZ=52 is obtained. This value is in good agreement with theoretical values and with a value of 0.875±0.028 predicted by the best fit curve of Bambyneket al.     

Spin-spin relaxation in slightly ferroelectric KH2AsO4 and BaTiO3:Mn2+

An approximate theory of dipolar relaxation by the soft modes of magnetic vacancies and dislocations gives $\text{2}\text{3}$ and 1 for the power-law exponents of T₂, while proton T₁ and EPR linewidth measurements yield 0.67 ± 0.04 and 1.0 ± 0.1.