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1.
Statistical properties of the realistic energy spectra of the odd-odd nuclei 106Ag, 198Au, 134Cs, 40K and 94Rb, calculated within the Interacting Boson Fermion Fermion Model, are investigated by means of the Δ3 statistics and the Nearest Neighbor Spacing Distribution method. New probability distribution function, which describes well the calculated results and enables the characterization of chaos with a physically meaningfull parameter, is proposed. Level spacing fluctuations of the examined nuclei exhibit the transitional behavior between Poisson and GOE limits, revealing different degrees of chaoticity in their dynamics. 相似文献
2.
The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd3+ ions in CaNb2O6 crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10−20 cm2 with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd3+ ions in CaNb2O6 crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω
t
are Ω
2=5.321×10−20 cm2,Ω
4=1.734×10−20 cm2,Ω
6=2.889×10−20 cm2. The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β
1=36.03%,β
2=52.29%,β
3=11.15%,β
4=0.533%. The emission cross section at 1062 nm is 9.87×10−20 cm2. 相似文献
3.
D. Ebert R. N. Faustov V. O. Galkin 《The European Physical Journal C - Particles and Fields》2009,60(2):273-278
Masses of the ground-state light tetraquarks are dynamically calculated in the framework of the relativistic diquark–antidiquark
picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark–gluon interaction
in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV, f
0(600) (σ), K
0*(800) (κ), f
0(980) and a
0(980), agree well with the light-tetraquark interpretation. 相似文献
4.
Jeong Ho Ryu Hyong Sik Won Youn-Gon Park Sang Hyun Kim Won Young Song Hideo Suzuki Chulsoo Yoon 《Applied Physics A: Materials Science & Processing》2009,95(3):747-752
Rare-earth-doped oxynitride or nitride compounds have been reported to be photoluminescent and may then serve as new phosphors
because of their good thermal and chemical stabilities. In this work, Eu2+-doped β-SiAlON phosphor with a composition of Eu
x
Si6−z
Al
z
O
z
N8−z
(x=0.018, z=0.23) was prepared by gas-pressured solid state reaction. The crystallinity and particle morphology of the prepared phosphor
were characterized. The Stokes shift and zero-phonon line were calculated mathematically and estimated from the spectral data.
The temperature dependence of photoluminescence was measured from 25 to 250°C. The prepared Eu2+-doped β-SiAlON green phosphor showed superior thermal quenching property compared to silicate (SrBaSiO4:Eu2+) green phosphor. The white light-emitting diode (LED) back-lighting unit (BLU) using the prepared β-SiAlON:Eu2+ green phosphor exhibited higher color gamut than a commercial silicate phosphor. 相似文献
5.
This contribution summarizes the work explained in arXiv:hep-ph/0608290 where we perform a non-perturbative chiral study of
the masses of the lightest pseudoscalar mesons. The pseudoscalar self-energies are calculated by the evaluation of the scalar
self-energy loops with full S-wave meson-meson amplitudes taken from Unitary Chiral Perturbation Theory (UCHPT). These amplitudes, among other features,
contain the lightest nonet of scalar resonances σ, f
0(980), a
0(980) and κ. The self-energy loops are regularized by a proper subtraction of the infinities within a dispersion relation formulation
of the amplitudes. Values for the bare masses of pions and kaons and the η
8 mass are obtained. We then match to the self-energies from standard Chiral Perturbation Theory (CHPT) to O(p
4) and resum higher orders from our calculated scalar self-energies. The dependence of the self-energies on the quark masses
allows a determination of the ratio of the strange-quark mass over the mean of the lightest-quark masses, m
s/
, in terms of the O(p
4) CHPT low-energy constant combinations 2L
r
8 - L
r
5 and 2L
r
6 - L
r
4. In this way, we give a range for the values of these low-energy counterterms and for 3L
7 + L
r
8, once the η-meson mass is invoked. The low-energy constants are further constraint by performing a fit to the recent MILC lattice data
on the pseudoscalar masses, and m
s/
= 25.6±2.5 results. This value is consistent with 24.4±1.5 from CHPT and phenomenology and more marginally with the value
27.4±0.5 obtained from pure perturbative chiral extrapolations of the MILC lattice data to physical values of the lightest-quark
masses. 相似文献
6.
7.
L. Siurakshina B. Paulus V. Yushankhai 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):445-450
Two types of oxygen-deficient perovskites RBaCo2O5.5(R=Ho,Gd) related to the “122” type structure (a
p
× 2a
p
× 2a
p
) have been studied on the basis of ab initio cluster calculations. We consider the peculiar behavior of the trivalent ions
Co3+(3d
6) in either octahedral or pyramidal oxygen coordinations, which is related to a structural first-order phase transition in
both compounds. Relative energy positions of low spin (LS, S = 0), intermediate spin (IS, S = 1) and high spin (HS, S = 2) electron configurations are calculated for the low-and high-temperature lattice structures of RBaCo2O5.5. A combined analysis of the calculated results and experimental structural data leads to a simple model that captures the
most prominent features of the phase transition common to both compounds. 相似文献
8.
C. Thierfelder P. Schwerdtfeger F. P. Heßberger S. Hofmann 《The European Physical Journal A - Hadrons and Nuclei》2008,36(2):227-231
The K -shell and L -shell ionizations potentials for 268
109Mt were calculated at the Dirac-Hartree-Fock level taking into account quantum electrodynamic and finite nuclear-size effects.
The K
α1 transition energies for different ionization states are accurately predicted and compared with recent experiments in the
α -decay of 272
111Rg . 相似文献
9.
Catherine Silvestre 《The European Physical Journal C - Particles and Fields》2009,61(4):841-845
In this paper, we calculate the decay rates of the D
+→D
0
e
+
ν, D
S
+→D
0
e
+
ν,
, D
S
+→D
+
e
−
e
+ and B
S
0→B
0
e
−
e
+ semileptonic decay processes, in which only the light quarks decay, while the heavy flavors remain unchanged. The branching
ratios of these decay processes are calculated with the flavor SU(3) symmetry. The uncertainties are estimated by considering
the SU(3) breaking effect. We find that the decay rates are very tiny in the framework of the standard model. We also estimate
the sensitivities of the measurements of these rare decays at future experiments, such as BES-III, super-B and LHC-b. 相似文献
10.
J. K. Baria 《Czechoslovak Journal of Physics》2004,54(4):469-485
A model pseudopotential depending on an effective core radius but otherwise parameter free is used to study the interatomic
interactions, phonon dispersion curves (inq and r-space analysis), phonon density of states, mode Grüneisen parameters, dynamical elastic constants (C
11,C
12 andC
44), bulk modulus (B), shear modulus (C′), deviation from Cauchy relation (C
12–C
44), Poisson’s ratio (σ), Young’s modulus (Y), behavior of phonon frequencies in the elastic limit independent of the direction (Y
1), limiting value in the [110] direction (Y
2), degree of elastic anisotropy (A), maximum frequencyω
max, mean frequency 〈ω〉, 〈ω
2〉1/2=(〈ω〉/〈ω
−1〉)1/2, fundamental frequency 〈ω
2〉, and propagation velocities of the elastic constants in Cu, Ag, Au, Ni, Pd, and Pt. The contribution of s-like electrons
is calculated in the second-order perturbation theory for the model potential while that of d-like electrons is taken into
account by introducing repulsive short-range Born-Mayer like term. Very recently proposed screening function due to Sarkar
et al. has been used to obtain the screened form factor. The theoretical results are compared with experimental findings wherever
possible. A good agreement between theoretical investigations and experimental findings has proved the ability of our model
potential for predicting a large number of physical properties of transition metals. 相似文献
11.
K. Azizi R. Khosravi V. Bashiry 《The European Physical Journal C - Particles and Fields》2008,56(3):357-370
Taking into account the gluon correction contributions to the correlation function, the form factors relevant to the rare
decays are calculated in the framework of the three-point QCD sum rules, where X stands for axial vector particle, AV(D
s1), and vector particles, V(D
*,D
s
*). The total decay width as well as the branching ratio of these decays are evaluated using the q
2 dependent expressions of the form factors. A comparison of our results with the predictions of the relativistic constituent
quark model is presented. 相似文献
12.
13.
Kuo-Feng Lin Ching-Ju Pan Wen-Feng Hsieh 《Applied Physics A: Materials Science & Processing》2009,94(1):167-171
Calculating the electronic structure and the density of states in the wurtzite structure of Zn1−x
Mg
x
O (ZMO) alloys using sp3 semi-empirical tight-binding model, we observed increases of both band gap and electron effective mass that agree with the
experimental results as increasing Mg composition up to x=0.3. From the calculated total density of states, the increasing electron effective mass is a result of less orbital overlap
of cation sites due to extra density of modes coming from Mg3s and Mg3p orbitals as introducing more Mg composition. Additionally,
reducing electronegative characteristic of oxygen was caused by that the O2p was less localized around the oxygen atom. 相似文献
14.
L. Ciaffoni B. L. Cummings W. Denzer R. Peverall S. R. Procter G. A. D. Ritchie 《Applied physics. B, Lasers and optics》2008,92(4):627-633
High resolution diode laser spectroscopy has been applied to the detection of hydrogen sulphide at ppm levels utilizing different
transitions within the region of the ν
1+ν
2+ν
3 and 2ν
1+ν
2 combination bands around 1.58 μm. Suitable lines in this spectral region have been identified, and absolute absorption cross
sections have been determined through single-pass absorption spectroscopy and confirmed in the Doppler linewidth regime using
cavity enhanced absorption spectroscopy (CEAS). The desire for a sensitive system potentially applicable to H2S sensing at atmospheric pressure has led to an investigation on suitable transitions using wavelength modulation spectroscopy
(WMS). The set-up sensitivity has been calculated as 1.73×10−8 cm−1 s1/2, and probing the strongest line at 1576.29 nm a minimum detectable concentration of 700 ppb under atmospheric conditions
has been achieved. Furthermore, pressure broadening coefficients for a variety of buffer gasses have been measured and correlated
to the intermolecular potentials governing the collision process; the H2S–H2S dimer well depth is estimated to be 7.06±0.09 kJ mol−1. 相似文献
15.
M.?Silies H.?Witte S.?Linden J.?Kutzner I.?Uschmann E.?F?rster H.?Zacharias 《Applied Physics A: Materials Science & Processing》2009,96(1):59-67
The interaction of ultrashort laser pulses with solid state targets is studied concerning the production of short X-ray pulses
with photon energies up to about 10 keV. The influence of various parameters such as pulse energy, repetition rate of the
laser system, focusing conditions, the application of prepulses, and the chirp of the laser pulses on the efficiency of this
highly nonlinear process is examined. In order to increase the X-ray flux, the laser pulse energy is increased by a 2nd multipass
amplifier from 750 μJ to 5 mJ. By applying up to 4 mJ of the pulse energy a X-ray flux of 4×1010 Fe K
α
photons/s or 2.75×1010 Cu K
α
photons/s are generated. The energy conversion efficiency is therefore calculated to η
Fe≈1.4×10−5 and η
Cu≈1.0×10−5. The X-ray source size is determined to 15×25 μm2. By focusing the produced X-rays using a toroidally bent crystal a quasi-monochromatic X-ray point source with a diameter
of 56 μm×70μm is produced containing ≈104 Fe K
α1 photons/s which permits the investigation of lattice dynamics on a picosecond or even sub-picosecond time scale. The lattice
movement of a GaAs(111) crystal is shown as a typical application. 相似文献
16.
J. L. Deng K. H. Su X. Wang Q. F. Zeng L. F. Cheng Y. D. Xu L. T. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):21-35
The most stable structures of gaseous Si
m
C
n
(3 ⩽ n+m ⩽ 6) clusters in their ground electronic states are determined with the high level electronic correlation method QCISD(T)/g3large.
Thermodynamic properties on heat capacity (C
p,m
Θ), entropy (S
m
Θ), Gibbs energy function (−[G
Θ −H
Θ(T
r
)]/T) and enthalpy function (H
Θ−H
Θ(T
r
)) are predicted with standard statistical thermodynamics using the structure parameters and vibrational frequencies obtained
with B3PW91/6-31G(d) method combined with the electronic excitation energies determined with time dependent density functional (TD DFT) method
at B3PW91/6-31G(d) level. The electronic energies are calculated with the accurate model chemistry method at G3(QCI) level of theory and the
Δ
f
H
m
Θ (0 K), Δ
f
H
m
Θ (298.15 K) and Δ
f
G
m
Θ (298.15 K) values are predicted. The heat capacities C
p,m
Θ(T) as a function of temperature within 298.15-2000 K are fitted into analytical equations. The thermodynamic functions at higher
temperatures are determined classically by using these equations. Most of the results obtained in this work are consistent
with the available experiments. 相似文献
17.
Roland Schmidt Erik McNellis Wolfgang Freyer Daniel Brete Tanja Gießel Cornelius Gahl Karsten Reuter Martin Weinelt 《Applied Physics A: Materials Science & Processing》2008,93(2):267-275
Self-assembled monolayers (SAMs) of 4-trifluoromethyl-azobenzene-4′-methyleneoxy-alkanethiols (CF3– C6H4–N=N–C6H4–O–(CH2)
n
–SH on (111)-oriented poly-crystalline gold films on mica were examined by X-ray photoelectron spectroscopy (XPS) and X-ray
absorption spectroscopy (XAS). The spectra are analyzed with the help of density-functional-theory calculations of the isolated
molecule. Only one doublet is detected in the sulphur 2p spectra of the investigated SAMs, consistent with a thiolate bond of the molecule to the gold surface. The C 1s XP spectra and the corresponding XAS π
* resonance exhibit a rich structure which is assigned to the carbon atoms in the different chemical surroundings. Comparing
XPS binding energies of the azobenzene moiety and calculated initial-state shifts reveals comparable screening of all C 1s core holes. While the carbon 1s XPS binding energy lies below the π
*-resonance excitation-energy, the reversed order is found comparing core ionization and neutral core excitation of the nitrogen 1s core-hole of the azo group. This surprising difference in core-hole binding energies is interpreted as site-dependent polarization
screening and charge transfer among the densely packed aromatic moieties. We propose that a quenching of the optical excitation
within the molecular layer is thus one major reason for the low trans to cis photo-isomerization rate of azobenzene in aromatic-aliphatic
SAMs. 相似文献
18.
S. Gołvab P. Solarz G. Dominiak-Dzik T. Lukasiewicz M. Świrkowicz W. Ryba-Romanowski 《Applied physics. B, Lasers and optics》2002,74(3):237-241
Crystals of YVO4:Ho were grown by the Czochralski method. The structure of the low-energy levels of Ho3+ has been estimated experimentally. Intensity parameters, radiative lifetimes, and branching ratios have been calculated in
the framework of the Judd–Ofelt theory. The influence of temperature on luminescence lifetimes has been investigated. The
calculated nonradiative transition rate was compared with the energy-gap law. The potential laser gain for the 5
I
7–5
I
8 transition has been estimated.
Received: 27 June 2001 / Final version: 10 December 2001 / Published online: 7 February 2002 相似文献
19.
We investigate the state on the Fermion algebra which gives rise to the thermodynamic limit of the Gibbs ensemble in the two-dimensional Ising model on a half lattice with nearest neighbour interaction. It is shown that the operatorP
–
in the GNS space, which performs the essential functions of the renormalized transfer matrix, has a quasi-particle structure. 相似文献
20.
S. Rai Choudhury A. S. Cornell Naveen Gaur 《The European Physical Journal C - Particles and Fields》2008,58(2):251-259
Flavor changing neutral current (FCNC) decays of the B-meson are a very useful tool for studying possible physics scenarios beyond the standard model (SM), where of the many FCNC
modes radiative, purely leptonic and semi-leptonic decays of the B-meson are relatively clean tests. Within this context, the BELLE collaboration has measured the process B→K
*
γ and also searched for the B→K
1(1270)γ process. Theoretical analyses of these processes are yielding similar values of the relevant form factors. In this work we
have used this upper bound in studying the angular correlations for the related semi-leptonic decay mode B
−→K
1−(1270)(→ρ
0
K
−)ℓ
+
ℓ
−, where we have used the form factors that have already been estimated for the B→K
1(1270)γ mode. Note that the additional form factors that are required were calculated using large energy effective theory (LEET). 相似文献