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1.
V. A. Shaburov A. E. Sovestnov Yu. P. Smirnov A. V. Tyunis H. Drulis M. Drulis 《Physics of the Solid State》1998,40(8):1265-1268
The population of the 4f, 5d, and 6s shells of rare-earth atoms in RHx hydrides (R=Ce, Sm, Yb; x≈2–3) has been studied by the x-ray line-shift method. The population of the 5d and 6s shells of Ce and Sm atoms, and the charge on them in metals and hydrides, were determined from experiment and calculated
within the Hartree-Fock-Dirac (Koopmans) model. The decrease of the charge on Ce and Sm revealed upon transition from the
metal to the hydride argues unambiguously for the anionic (hydride) model. In YbHx with x⩾2, the structural transition is accompanied by a strongly pronounced electronic transition from divalent to a noninteger-valence
state
.
Fiz. Tverd. Tela (St. Petersburg) 40, 1393–1396 (August 1998) 相似文献
2.
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
3.
Zhen-Jun Xiao Xin-Fen Chen Dong-Qin Guo 《The European Physical Journal C - Particles and Fields》2007,50(2):363-371
In this paper, we calculate the branching ratios and CP-violating asymmetries for Bs→ρ±K∓, ρ0K̄0 and ωK̄0 decays in the perturbative QCD factorization approach. The theoretical predictions for the CP-averaged branching ratios of
the considered decays are Br(Bs→ρ±K∓)≈24.7×10-6, Br(Bs→ρ0K̄0)≈1.2×10-7 and Br(Bs→ωK̄0)≈1.7×10-7; and we also predict large CP-violating asymmetries for the considered decay modes. Specifically, the large ACP
dir(Bs→ρ±K∓) at -12% level plus large branching ratio at 10-5 level are measurable in the forthcoming LHC-b experiments.
PACS 13.25.Hw; 12.38.Bx; 14.40.Nd 相似文献
4.
Y. Gangrsky K. Marinova S. Zemlyanoi M. Avgoulea J. Billowes P. Campbell B. Cheal B. Tordoff M. Bissell D. H. Forest M. Gardner G. Tungate J. Huikari H. Penttilä J. Äystö 《Hyperfine Interactions》2006,171(1-3):209-215
Collinear laser spectroscopy experiments on the ScII transition 3d4s
3D2→3d4p
3F3 at λ ≈ 363.1 nm were performed on the 42–46Sc isotopic chain using an ion guide isotope separator with a cooler–buncher. Isotope and isomer shifts and hyperfine structures
of five ground states and two isomers were measured. Preliminary results on the nuclear moments and charge radii changes deduced
from these measurements are reported. 相似文献
5.
P. Lunkenheimer G. Knebel A. Pimenov G. A. Emel’chenko A. Loidl 《Zeitschrift für Physik B Condensed Matter》1995,99(1):507-516
The complex conductivity of La2CuO4+δ has been investigated for frequencies 20 Hz≤ν≤4 GHz and temperatures 1.5K≤T≤450 K. Two single crystals with δ≈0 and δ≈0.02
were investigated, using dc (four-probe), reflectometric and contact-free techniques. At high temperatures the dc conductivity
is thermally activated with low values of the activation energy. For low temperatures Mott's variable range hopping dominates.
The real and imaginary parts of the ac conductivity follow a power-law dependence σ∼v
s, typical for charge transport by hopping processes. A careful analysis of the temperature dependence of the ac conductivity
and of the frequency exponents has been performed. It is not possible to explain all aspects of the ac conductivity in La2CuO4+δ by standart hopping models. However, the observed minimum in the temperature dependence of the frequency exponents strongly suggests tunneling of large polarons as dominant transport process. 相似文献
6.
By means of a N2-laser pumped dye-laser (P
L
≈20kW, Δv
L
< 10 GHZ) different two-photon resonant four-wave coupling processes in Ba vapour (n
Ba≈1016 cm−3) using the Ba states 6s8s
1
S
o and 7s5d
1
D
2 were investigated. Coherent line radiation with conversion rates up to 10−3 was generated within the range of λ=190–200 nm by sumfrequency mixingv
UV=2v
1+v
2 of 3 laser photons and within the range of λ=250–380 nm by couplingv
UV=2v
1±v
IR of 2 laser photons with one photonv
IR stimulated emitted in laser-induced Ba transitions. For the second coupling type the various nonlinear processes contributing
to the formation of the coupling components are discussed. The power of the UV-component as function of inensity and resonance
detuning of the laser as well as on the phase-mismatch was calculated on the basis of the small signal theory and compared
to the experimental data. 相似文献
7.
Doppler-limited high resolution laser optogalvanic spectra of six transitions of rhenium lying in the range 560–620 nm have
been recorded. Isotope shifts between the two natural isotopes of rhenium,185Re and187Re, have been calculated in all the six transitions. Hyperfine coupling constants for eight levels belonging to the configurations
5d
56s
2, 5d
66s, 5d
46s
26p and 5d
56s6p are reported. Wherever possible our constants are compared with those given by others. 相似文献
8.
Acoustic relaxation in undeformed and plastically deformed CsI single crystal has been studied using the composite oscillator
technique at frequencies (1–7) × 105 Hz in the temperature range 2–15 K. Plastic deformation leads to appearance of an internal friction peak localized in the
temperature interval 4–5 K. It is shown that the peak shifts towards higher temperatures when increasing the vibration frequency
and corresponds to a thermally activated relaxation process with very low values of the activation energyU ≈ 1.9×10−3 eV and the attack frequencyν
0≈6.7 × 103 s−1. Interaction of sound with dislocation kinks migrating in the second order Peierls relief is considered as a possible mechanism
of the peak.
Research was made possible in part by Grants U9T000 and U9T200 from the International Science Foundation and supported in
part by the Fundamental Research Foundation of Ukraine (Project 2.4/156 “Bion”). 相似文献
9.
We have calculated relativistic energies, Landé factors and lifetimes for 5d6s
2, 5d
26s, 6s
2
ns (n = 7–14), 6s
2
nd (n = 6–25), 6s
2
ng (n = 5–7), 6s
2
np (n = 6–25), 5d6s6p and 6s
2
nf (n = 5–23) excited levels outside the core [Xe]4f14 in neutral lutetium (Z = 71) using Cowan’s relativistic Hartree-Fock (HFR) method. The results obtained have been compared
with other calculations and experiments. 相似文献
10.
D. M. Eagles 《Zeitschrift für Physik B Condensed Matter》1975,22(1):79-87
The contributions of 4f, 5d and 6s electrons to the saturation magnetic moments and magnetic hyperfine fields in the heavy rare earth metals are calculated using the model described in the previous paper. It is found that 4f shell moments are reduced from their free ion values by amounts varying from 0.05µ
B
in Gd to several tenths of a Bohr magneton in Tb and Dy, in qualitative agreement with a recent published analysis of neutron diffraction results in Tb, but that the calculated total saturation moments in Tb and Dy are slightly larger than commonly accepted experimental values. After 6s contributions to magnetic hyperfine fields are determined by fitting observations in Gd, the predicted differences between the fields for metals and those for free ions are such that the estimated uncertainty ranges of the theoretical values overlap the experimental ranges. The 5d contribution in the model is negative, varying from about –40 kOe in Tb to –200 kOe in Er. Electric field gradients are also analysed. Observed results can be fitted if the average effective Sternheimer screening factorR
d
*
for 5d electrons in the metals satisfies (1 —R
d
*
)0.7. 相似文献
11.
We study stable “bookshelf” smectic-A structures within a very thin plane-parallel cell of thickness L in which the mismatch between surface preferred (d
s) and intrinsic (d0) smectic layer thicknesses occurs. The Landau-Ginzburg approach based on a complex smectic order parameter is used. For a
weak enough smectic positional anchoring strength W smectic layers adopt the modified bookshelf profile. In a thick enough cell with increasing W a lattice of edge dislocations is continuously formed at the confining surfaces and then depinned from them. The structure
with dislocations is formed when the condition d
0/(
d
0/d
s - 1) ∼ 2 is fulfilled, where is the positional surface anchoring extrapolation length. If the cell is thin enough the dislocations formed at opposite
cell plates annihilate and consequently the smectic layers adopt a locked bookshelf structure. This transition is discontinuous
and takes place when d
0/(L
d
0/d
s - 1) ∼ 5 is realized. To observe these transitions in a cell of thickness L∼ 1μm the conditions W∼ 10-6
J/m
2 and
d
0/d
s - 1∼ 5 . 10-4 have to be fulfilled. All the three qualitatively different structures coexist at the triple point.
Received 21 February 2002 相似文献
12.
A. E. Sovestnov V. A. Shaburov Yu. P. Smirnov A. V. Tyunis 《Physics of the Solid State》1999,41(10):1577-1579
The electronic structure (population of the valence d and s shells) of Y and Pr in the RM2 Laves phases with Mg, Al, Fe, Co, and Ni has been determined experimentally by the x-ray K-line shift method. It was found that the Y and Pr electronic structures in RM2 with Mg and Al are practically the same as in metals, but the distribution of the three outer electrons between the d and s shells in Y is essentially different from that in Pr. In the Laves phases with 3d metals (Fe, Co, or Ni), the outer-electron distributions between the d and s shells in Y and Pr are practically identical and do not depend on the d metal.
Fiz. Tverd. Tela (St. Petersburg) 41, 1721–1723 (October 1999) 相似文献
13.
Yu. P. Snitovskii 《Technical Physics》2009,54(6):907-911
A near-electrode nonuniform magnetic field crossed with an electric field is found to strongly affect the rate of etching
of silicon dioxide on glass substrates in a CF4 + O2 plasma when the Larmor frequency (≈109 s−1) is much higher than the frequency of collisions of an electron with surrounding plasma particles (≈106 s−1) and the frequency of the applied rf electric field (≈107 s−1). The confinement of electrons by the magnetic field in the immediate vicinity of the substrate surface to be treated increases
the rate of generation of chemically active particles, which increases the etching rate of silicon dioxide. 相似文献
14.
Andre Toom 《Journal of statistical physics》1997,88(1-2):347-364
We consider space- and time-uniformd-dimensional random processes with linear local interaction, which we call harnesses and which may be used as discrete mathematical
models of random interfaces. Their components are rea random variablesa
s
t
, wheres ∈ Z
d
andt=0, 1, 2.,... At every time step two events occur: first, every component turns into a linear combination of itsN neighbors, and second, a symmetric random i.i.d. “noise”v is added to every component. For any σ ∈Z
d
+
define Δσ
a′
s
as follows. If σ=(0,...,0), σ=(0,...,0), Δσ
a
s
t
=a
s
t
. Then by induction,
wheree
i is thed-dimensional vector, whoseith component is one and other components are zeros. Denote |σ| the sum of components of σ. Call a real random variable ϕ symmetric
if it is distributed as −ϕ. For any symmetric random variable ϕpower decay or P-decay is defined as the supremum of thoser for which therth absolute moment of ϕ is finite. Convergence a.s., in probability and in law whent→∞ is examined in terms of P-decay(v): Ifd=1, σ=0 ord=2, σ=(0,0), Δσ
a
s
t
diverges. In all the other cases: If P-decay(v)<(d+2)/(d+|σ|), Δσ
a
s
t
diverges; if P-decay(v)>(d+2)/(d+|σ|), Δσ
a
s
t
, converges and P-decay(ν) For any symmetric random variable ϕexponential decay or E-decay is defined as the supremum of thoser for which the expectation of exp(|x|r) is finite. Let E-decay(v)>0. Whenever Δσ
a
s
t
converges (that is, ifd>2 or |σ|>0: Ifd>2, E-decay(lima
s
t
)=min(E-decay(v),d+2/2); if |σ|=1, E-decay (lim Δσ
a
s
t
)=min(E-decay(ν),d+2); if |σ| ⩾, E-decay (lim Δσ
a
s
t
)=E-decay(ν). 相似文献
15.
W. Zhang S. You C. Sun Y. Zhang J. Xu Z. Ma Y. Feng H. Liu P. Quinet é. Biémont Z. Dai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(1):1-8
First laser spectroscopic measurements of the 6s5d3D1-6s6p1P1 and 6s5d3D2-6s6p1P1 transitions in several isotopes of atomic barium have been performed. The hyperfine structure of these transitions was optically
resolved and isotope shifts for even and odd isotopes were determined. The isotope shifts show a deviation from their expected
behavior for odd isotopes in an analysis based on King-plots. This observation puts atomic structure calculations at test
because available theories do not predict this. A profound understanding of the wavefunctions for heavy alkaline earth systems
like barium (Ba) and radium (Ra) is essential for a theoretical evaluation of their sensitivity to fundamental symmetry breaking
effects such as they could be observed, e.g., through permanent electric dipole moments. Further the absolute frequency of
the 6s2
1S0-6s6p3P1 intercombination line in 138Ba was determined to be 12 636.6232(1) cm-1. 相似文献
16.
A. V. Tyunis V. A. Shaburov Yu. P. Smirnov A. E. Sovestnov 《Physics of the Solid State》1997,39(9):1337-1340
The electronic structure of U and Ge in the solid solutions U(Al1−x
Gex)3 is investigated by measuring x-ray line shifts. It is shown that uranium has the mixed valence U3+ [Rn](5f
3)-U4+ [Rn](5f
2) over the entire composition range (0⩽x⩽1) and that the population of the uranium 5f shell increases by ∼0.28 5f electrons/U atom from UAl3 (x=0) to UGe3 (x=1). The electronic structure of Ge is close to the electronic structure of Ge metal over the entire composition range 0<x⩽1. No variation of the population of the Ge 4p shell is detected to within the experimental error (∼0.1 4p electrons/Ge atom) as the composition varies from x=0.2 to 1. It is established that the delocalization of a U 5f electron occurs as a result of its transition to the s or d band of the same uranium atom.
Fiz. Tverd. Tela (St. Petersburg) 39, 1505–1508 (September 1997) 相似文献
17.
R. Kadono R. F. Kiefl J. H. Brewer G. M. Luke T. Pfiz T. M. Riseman B. J. Sternlieb 《Hyperfine Interactions》1991,64(1-4):635-640
The diffusion rate of muonium in the III–V compound semiconductor GaAs has been determined from measurements of muon spinT
1 relaxation induced by motion in the presence of nuclear hyperfine interactions. It is shown for the first time in a semiconductor
that (a) there is a crossover of the transport mechanism at about 90 K from stochastic to zero-phonon hopping, as evidenced
by a steep rise in the hop rate at lower temperatures, and that (b) the muonium diffuses at the hop rate of 1010 s−1 (corresponding diffusion constantD≈10−6 cm2s−1) at lower temperatures as well as at room temperature. 相似文献
18.
Feoktistov N. A. Sakharov V. I. Serenkov I. T. Tolmachev V. A. Korkin I. V. Aleksenskii A. E. Vul’ A. Ya. Golubev V. G. 《Technical Physics》2011,56(5):718-724
The aerosol deposition of detonation nanodiamonds (DNDs) on a silicon substrate is comprehensively studied, and the possibility
of subsequent growth of nanocrystalline diamond films and isolated particles on substrates coated with DNDs is demonstrated.
It is shown that a change in the deposition time and the weight concentration of DNDs in a suspension in the range 0.001–1%
results in a change in the shape of DND agglomerates and their number per unit substrate surface area N
s
from 108 to 1011 cm−2. Submicron isolated diamond particles are grown on a substrate coated with DND agglomerates at N
s
≈ 108 cm−2 using microwave plasma-enhanced chemical vapor deposition. At N
s
≈ 1010 cm−2, thin (∼100 nm) nanodiamond films with a root-mean-square surface roughness less than 15 nm are grown. 相似文献
19.
The separation betweenT=0 andT=1 centroids of the empirical effective interaction is fairly large for the (d
3
2/−1
f
7/2)JT particle-hole interaction as compared to nearby (f
7/2)2
JT and (d
5/2)2
JT particle-particle interactions. This interesting feature of the empirical effective interaction is shown to arise as a consequence
of renormalization of the effective interaction as one truncates the configuration space from (s−d)−1(f−p)1 to (d
3
2/−1
f
7/2) and from (f−p)2 and (s−d)2 configurations to (f
7/2)2 and (d
5/2)2 respectively. 相似文献
20.
R.A. Radhi 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):387-392
Electron scattering Coulomb form factors for the single-particle quadrupole transitions in p-shell and sd-shell nuclei have been studied. Core polarization effects are included through a microscopic theory that includes excitations
from the core orbits up to higher orbits with 2ω excitations. The modified surface delta interaction is adopted as a residual
interaction. The results are discussed for the ( 1p
1/2
-1↦1p
3/2
-1) proton transition in 15N, ( 1d
5/2↦2s
1/2) neutron transition in 17O and ( 1d
3/2
-1↦2s
1/2
-1) proton transition in 39K. The inclusion of core polarization effects modifies the form factors markedly and describes the experimental data very
well in both the absolute strength and the momentum transfer dependence.
Received: 18 April 2002 / Accepted: 1 July 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: baguniv@uruklink.net
Communicated by A. Molinari 相似文献