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1.
The results of a Compton profile study on polycrystallineα-Mn are reported. Our measurement are compared with theoretical results computed for different 3d-4s electron configurations within the RFA model. Best agreement between the measured and calculated values is found for 3d
5·44s
1·6 configuration. Theoretical Compton profile ofγ-Mn calculated using the same procedure is close to that for bcc phase with similar electron configurations. 相似文献
2.
The Compton profile of tantalum (Ta) has been measured using IGP type coaxial photon detector. The target atoms were excited
by means of 59.54 keV γ-rays from Am-241. The measurements were carried out on a high purity thin elemental foil. The data
were recoreded in a 4 K multichannel analyzer. These data duly corrected for various effects are presented and compared with
theoretical and measured values. Best agreement with experiment is found for the 5d36s2 electron configuration 相似文献
3.
In this paper we report the experimental Compton profile of polycrystalline molybdenum. The measurements have been made by
scattering 59.54 keVγ-rays and are compared with the recent band structure calculation of Janiet al. [4]. These results have also been compared with our calculation based on the renormalized-free-atom model for different 4d-5s configurations. It is found that the present experimental data are relatively in good agreement with the band structure calculation. 相似文献
4.
The isotropic Compton profile of iridium, measured using 59.54 keVγ-rays, is reported in this paper. The results are compared with the theoretical Compton profiles from APW method with and
without incorporating electron correlation effects. It is seen that correlation effects improve the agreement between the
experiment and theory. Comparison with the renormalized-free-atom (RFA) model calculations has also been made. Behaviour ofd-band electrons in Ir and some other 5d transition metals is discussed in terms of broadening in their Compton profiles. 相似文献
5.
We report on the lattice location of indium in and the magnetic ordering of manganese in its α- and β-phases, as seen by perturbed
angular correlation. Quadrupole interaction spectra show that indium prefers to replace Mn atoms of type I in α-Mn, but replaces
type II atoms in the β-Mn structure. The interaction strength equalseQV
zz
/h=3.6 (6) MHz in α-Mn and 172.3 (3) MHz with ν=0.13 (1) in β-Mn. No magnetic ordering down to 4.2 K was observed in β-Mn, while
belowT
N
=95 K in the α-Mn phase, a magnetic hyperfine interaction appears indicating two distinct magnetic probe environments. The
hyperfine field, when measured atT=4.2 K, equals for 70% of the probes 6.33 (1) T, while the remaining fraction senses a 3.10 (4) T field. The magnitudes of
the hyperfine fields are essentially unaffected by a variety of conditions in the sample preparation. The ordering temperature,
on the contrary, turns out to be rather sensitive to residual impurities especially any oxygen contamination. 相似文献
6.
Ashcroft’s analytic bare ion pseudopotential form factor with a modified Hartree dielectric function has been employed to
represent the temperature dependent interionic potential. This potential includes both direct ion-ion interaction and indirect
ion-electron-ion interaction with and without the effects of ‘d’ bands, in some scantily studied complexbcc metals vizbcc Ti, Zr and Hf. The ab initio radial and tangential force constants extending out to 15th nearest neighbours are computed
for the metals. The said potential is used for predicting the binding energy, elastic constants and phonon dispersion of the
above mentioned metals and the results are satisfactorily compared with the corresponding measured data. 相似文献
7.
V. D. Borman M. A. Pushkin V. N. Tronin V. I. Troyan 《Journal of Experimental and Theoretical Physics》2010,110(6):1005-1025
The electronic properties of nanoclusters of transition (Ni, Co, Cr) and noble (Au, Cu) metals deposited on the surface of
highly oriented pyrolytic graphite (HOPG) are studied using the method of X-ray photoelectron spectroscopy. The laws of variation
of a change ΔE
b in the binding energies of core-level electrons in the initial (ΔE
i) and final (ΔE
f) states of atoms in nanoclusters, the intrinsic widths γ of photoelectron lines, and their singularity indices α as functions
of the metal cluster size d are determined. A qualitative difference in behavior of the ΔE
i(d) and α(d) values in metals of the two groups (Ni, Cr versus Co, Cu) is found. The values of the final-state energy (ΔE
f < 0) and the line width (Δγ > 0) in the clusters of all metals studied vary in a similar manner. It is shown that a significant
contribution to E
i is due to a transfer of the valence-shell electrons at the cluster-substrate interface, which is caused by the contact potential
difference. The value of an uncompensated charge per nanocluster is determined as a function of the cluster size and the number
of atoms in the cluster. The behavior of ΔE
f(d) is controlled by the Coulomb energy of a charged cluster and by a decrease in the efficiency of electron screening, which
is different in the metals studied. The broadening of photoelectron lines is determined by a spread of the cluster sizes and
by lower electron screening in the final Fermi system. An asymmetry of the core-level electron spectra of nanoclusters can
be explained using notions about the electron-hole pair excitation near the Fermi level. The effect of the structure of the
density of electron states in the d band of transition metals on the asymmetry of photoelectron lines is considered and it is concluded that this structure near
the Fermi level qualitatively changes with a decrease in the nanocluster size. The obtained results indicate that the behavior
of the electron subsystem of clusters of the d-metals in a size range of 2–10 nm under consideration is close to the behavior of a normal Fermi system. 相似文献
8.
The method of generalized least squares has been used to deconvolute the Compton profile measurements in nickel. The method
depends on two arbitrary parameters namely the cut-off parameterK and the damping factor λ. This has been discussed and a method suggested to optimize the damping parameter. 相似文献
9.
V. A. Shaburov A. E. Sovestnov Yu. P. Smirnov A. V. Tyunis 《Physics of the Solid State》1999,41(8):1246-1247
The shifts of the Kα
1 and Kβ
1 lines of all rare-earth (RE) metals (from La to Lu) have been measured experimentally by the x-ray shift method. The population
of the RE-metal 6s and 5d shells has been determined by comparing the experimental and theoretical shifts obtained within the Dirac-Fock (Koopmans)
model. Trivalent metals exhibit a monotonic cross-over from the 6s
≈25d
≈1 to 6s
≈15d
≈2 configuration with increasing atomic number.
Fiz. Tverd. Tela (St. Petersburg) 41, 1361–1362 (August 1999) 相似文献
10.
L. Bartosch P. Kopietz 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(1):29-36
We consider the effect of Coulomb interactions on the average density of states (DOS) of disordered low-dimensional metals
for temperatures T and frequencies ω smaller than the inverse elastic life-time 1/τ. Using the fact that long-range Coulomb interactions in two dimensions (2d) generate ln2-singularities in the DOS ν(ω) but only ln-singularities in the conductivity σ(ω), we can re-sum the most singular contributions
to the average DOS via a simple gauge-transformation. If σ(ω) > 0, then a metallic Coulomb gapν(ω) ∝ |ω|/e
4 appears in the DOS at T = 0 for frequencies below a certain crossover frequency Ω
2 which depends on the value of the DC conductivity σ(0). Here, - e is the charge of the electron. Naively adopting the same procedure to calculate the DOS in quasi 1d metals, we find ν(ω) ∝ (|ω|/Ω
1)1/2exp(- Ω
1/|ω|) at T = 0, where Ω
1 is some interaction-dependent frequency scale. However, we argue that in quasi 1d the above gauge-transformation method is on less firm grounds than in 2d. We also discuss the behavior of the DOS at finite temperatures and give numerical results for the expected tunneling conductance
that can be compared with experiments.
Received 28 August 2001 / Received in final form 28 January 2002 Published online 9 July 2002 相似文献
11.
Saulius Mickevičius Darius Germanas Ramutis K. Kalinauskas 《Central European Journal of Physics》2012,10(2):421-428
We present a new independent scheme of SO(3) group transformations suitable for the N particle system, composed of N − 1 and 1 particle subsystems, where N − 1 particles have their own intrinsic clusterization. The simple expressions for corresponding four-particle harmonic-oscillator
transformation brackets are presented, as well as their simplifications for the special values of mass ratio parameters d = 0, d → ∞ and d
1 = 0, d
1 → ∞. 相似文献
12.
Compton profile of cobalt has been calculated employing the renormalized-free-atom model for fcc as well as hcp phases choosing
several 3d-4s configurations. The results have been compared with recent gamma-ray measurements on polycrystalline Co. Best agreement between
theory and experiment is found for 3d
74s
2 configuration. Comparison with free electron model has also been made for this case. 相似文献
13.
The wave mechanics of two impenetrable hard core particles in a 1-D box is analyzed. Each particle in the box behaves like
an independent entity represented by a macro-orbital (a kind of pair waveform). While the expectation value of their interaction, 〈 V
HC
(x) 〉, vanishes for every state of two particles, the expectation value of their relative separation, 〈 x 〉, satisfies 〈 x 〉≥λ/2 (or q ≥ π/d, with 2d=L being the size of the box). The particles in their ground state define a close-packed arrangement of their wave packets (with
〈 x 〉= λ/2, phase position separation Δϕ = 2π and momentum |q
o| = π/d) and experience a mutual repulsive force (zero point repulsion) f
o
=h
2/2md
3 which also tries to expand the box. While the relative dynamics of two particles in their excited states represents usual
collisional motion, the same in their ground state becomes collisionless. These results have great significance in determining
a correct microscopic understanding of widely different many-body systems. 相似文献
14.
Masuo Suzuki 《Journal of statistical physics》1986,43(5-6):883-909
A short review is given concerning the quantum statistical Monte Carlo method based on the equivalence theorem(1) thatd-dimensional quantum systems are mapped onto (d+1)-dimensional classical systems. The convergence property of this approximate tansformation is discussed in detail. Some
applications of this geneal appoach to quantum spin systems are reviewed. A new Monte Carlo method, “thermo field Monte Carlo
method,” is presented, which is an extension of the projection Monte Carlo method at zero temperature to that at finite temperatures.
Invited talk presented at “Frontiers of Quantum Monte Carlo,” Los Alamos National Laboratory, September 3–6, 1985. 相似文献
15.
A systematic semiquantitative account of all aspects of the strong and electromagnetic interactions of all the newly discovered
hadronic states (theψ’s, theχ’s, etc.) is presented within the framework of the paracharge scheme. Extensions of ideas familiar from the SU3 classification scheme to SU4 are shown to provide an understanding of the new states seen in the decays ofψ (3.1) andψ′ (3.7), including their masses and gross decay characteristics. The decays ofψ (3.1) andψ′ (3.7) themselves are studied in some detail. Since these are of electromagnetic origin in the scheme, their electromagnetic
mixing with the resonance at 4.15 GeV (theP-state of the scheme) is important. Once this is taken into account, the resulting picture is in excellent agreement with
available data. 相似文献
16.
H. van Pee O. Bartholomy V. Crede A. V. Anisovich G. Anton R. Bantes Yu. Beloglazov R. Bogendörfer R. Castelijns A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(1):61-77
Photoproduction of π0-mesons was studied with the Crystal-Barrel detector at ELSA for incident energies from 300MeV to 3GeV. Differential cross-sections
dσ/dΩ, dσ/dt, and the total cross-section are presented. For E
γ < 3GeV, the angular distributions agree well with the SAID parametrization. At photon energies above 1.5GeV, a strong forward
peaking indicates t-channel exchange to be the dominant process. The rapid variations of the cross-section with energy and angle indicate production
of resonances. An interpretation of the data within the Bonn-Gatchina partial-wave analysis is briefly discussed. 相似文献
17.
Both parabola and ellipse separating schemes are used to study the solid solubilities for the binary alloy systems based on
the 13 rare earth metals. It has been found that the soluble elements can be separated from the insoluble ones by a parabolyy
1=a−bx
1
2
or an ellipse(x
2−m)2/c2+(y2−n)2/d2=1. The results show that the overall reliabilities of the solid solubilities for the 897 binary alloys based on the rare
earth metals are 89.2% and 92.8% for the parabola and ellipse regularities respectively. The constants a and b in the parabola
equation, andm, n, c andd in the ellipse equation are discussed, which can be related to some appropriate parameters for each host metal respectively. 相似文献
18.
Yu. P. Smirnov A. E. Sovestnov A. V. Tyunis V. A. Shaburov 《Physics of the Solid State》1998,40(8):1269-1271
The x-ray line shift method has been used to study the electronic state of Ce (the 4f population) and of its 4d and 5d partners in the CeM2 Laves phases (M=Fe, Co, Ni, Ru, Rh, Os, Pt, Mg, Al). It is shown that the valence of Ce in CeM2 decreases monotonically from the limiting value m≈3.35 to m≈3 with decreasing intracrystalline compression of Ce atoms. The population of the outer 4d and 5d orbitals of Ru, Rh, and Os in the Laves phases has been found to be larger than that in metals.
Fiz. Tverd. Tela (St. Petersburg) 40, 1397–1400 (August 1998) 相似文献
19.
S. Yu. Davydov 《Physics of the Solid State》1999,41(1):8-10
The cohesion-based approach developed earlier for describing the adsorptive properties of d-metal atoms on d substrates was used to calculate the self-diffusion on the (111) and (100) planes of fcc metals, and the (110) plane of bcc
metals. The results of the calculation are compared with the data obtained by other researchers and with available measurements.
Fiz. Tverd. Tela (St. Petersburg) 41, 11–13 (January 1999) 相似文献
20.
A new scheme is presented for the physical processes leading to the nuclear fusion reaction d(3He, 4He)p catalyzed by a negatively charged muon μ−. It is shown that the observable rate and yield of the nuclear reaction depend on a chain of ion-molecular reactions involving
the participation of the dμ 3He molecule. New calculations of the nuclear fusion rates in the dμ3He molecule are presented.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 89–94 (25 January 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献