共查询到20条相似文献,搜索用时 15 毫秒
1.
We performed optical spectroscopy measurement on a superconducting Ba0.6K0.4Fe2As2 single crystal with T{c}=37 K. Formation of the superconducting energy gaps in the far-infrared reflectance spectra below T{c} is clearly observed. A flat and close to unity reflectance is observed roughly below 150 cm;{-1} for Tor=T{c}. We determined the absolute value of the penetration depth at 10 K as lambda approximately 2000+/-80 A. A spectral weight analysis shows that the Ferrell-Glover-Tinkham sum rule is satisfied at low energy scale, less than 6Delta. 相似文献
2.
3.
Systems described by an O(n) symmetrical varphi;{4} Hamiltonian are considered in a d-dimensional film geometry at their bulk critical points. The critical Casimir forces between the film's boundary planes B_{j}, j=1,2, are investigated as functions of film thickness L for generic symmetry-preserving boundary conditions partial differential_{n}phi=c[over composite function]_{j}phi. The L-dependent part of the reduced excess free energy per cross-sectional area takes the scaling form f_{res} approximately D(c_{1}L;{Phi/nu},c_{2}L;{Phi/nu})/L;{d-1} when d<4, where c_{i} are scaling fields associated with the variables c[over composite function]_{i} and Phi is a surface crossover exponent. Explicit two-loop renormalization group results for the function D(c_{1},c_{2}) at d=4- dimensions are presented. These show that (i) the Casimir force can have either sign, depending on c_{1} and c_{2}, and (ii) for appropriate choices of the enhancements c[over composite function]_{j}, crossovers from attraction to repulsion and vice versa occur as L increases. 相似文献
4.
V. Rabinovich 《Russian Journal of Mathematical Physics》2013,20(4):508-522
We consider a diffraction problem in a multi-connected domain ?2 \ Γ, where Γ is an oriented graph with finitely many edges some of which are infinite. The problem is described by the Helmholtz equation (1) $\mathcal{H}u(x) = \rho (x)\nabla \cdot \rho ^{ - 1} (x)\nabla u(x) + k^2 (x)u(x) = 0,x \in \mathbb{R}^2 \backslash \Gamma ,$ where ρ and k are functions bounded together with all derivatives, and by the transmission conditions (2) $u_ + (t) - u_ - (t) = 0,t \in \Gamma \backslash \mathcal{V},$ (3) $a_ + (t)(\partial u/\partial n_t )_ + (t) - a_ - (t)(\partial u/\partial n_t )_ - (t) + a_0 (t)u(t) = f(t),t \in \Gamma \backslash \mathcal{V},$ where V is the set of vertices, a ± and a 0 are functions bounded on Γ, slowly oscillating discontinuous at the vertices in V, and slowly oscillating at infinity, and f ∈ L 2(Γ). Using Green’s function for the Helmholtz operator H, we introduce simple- and double-layer potentials and reduce the diffraction problem (1)–(3) to a boundary integral equation. The main objective of the paper is to study the essential spectrum, the Fredholm property, and the index of boundary operators on Γ associated with the problem (1)–(3). 相似文献
5.
采用基于第一性原理的密度泛函理论平面波超软赝势方法计算了 1/4ML Cs原子吸附 (2 × 2) GaN(0001) 表面的吸附能、能带结构、电子态密度、电荷布居数、功函数和光学性质. 计算发现, 1/4ML Cs 原子在 GaN(0001) 表面最稳定吸附位为 N 桥位, 吸附后表面仍呈现为金属导电特性, Cs原子吸附GaN(0001)表面后主要与表面 Ga 原子发生作用, Cs6s 态电子向最表面 Ga 原子转移, 引起表面功函数下降. 研究光学性质发现, Cs 原子吸附 GaN(0001) 表面后, 介电函数虚部、吸收谱、反射谱向低能方向移动. 相似文献
6.
A current algebra calculation of e+e-→4π± cross section is carried out using the axial current matrix element obtained from τ→π?ν. Assuming ?′→?+2π(I=0, l=0), the following results are obtained: for the A1 resonance, 1.05?mA ?1.15 GeV; for ?′, Γ?′(total)≈0.23 GeV, M?′≈1.5 GeV, Γ(?′→e+e-)≈0.4 keV×B?1(?′→?′ →?π+π). 相似文献
7.
We perform a first-principles simulation to study the electronic and optical properties of wurtzite Zn1 xCuxO.The simulations are based upon the Perdew-Burke-Ernzerhof form of generalised gradient approximation within the density functional theory.Calculations are carried out in different concentrations.With increasing Cu concentration,the band gap of Zn1 xCuxO decreases due to the shift of valence band.The imaginary part of the dielectric function indicates that the optical transition between O 2p states in the highest valence band and Zn 4s states in the lowest conduction band shifts to the low energy range as the Cu concentration increases.Besides,it is shown that the insertion of Cu atom leads to redshift of the optical absorption edge.Meanwhile,the optical constants of pure ZnO and Zn0.75Cu0.25O,such as loss function,refractive index and reflectivity,are discussed. 相似文献
8.
Sansonetti CJ Simien CE Gillaspy JD Tan JN Brewer SM Brown RC Wu S Porto JV 《Physical review letters》2011,107(2):023001
Optical frequencies of the D lines of (6,7)Li were measured with a relative accuracy of 5 × 10?11 using an optical comb synthesizer. Quantum interference in the laser induced fluorescence for the partially resolved D2 lines was found to produce polarization dependent shifts as large as 1 MHz. Our results resolve large discrepancies among previous experiments and between all experiments and theory. The fine-structure splittings for ?Li and ?Li are 10052.837(22) MHz and 10053.435(21) MHz. The splitting isotope shift is 0.599(30) MHz, in reasonable agreement with recent theoretical calculations. 相似文献
9.
High resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zi-Shan Xu 《中国物理 B》2022,31(12):123201-123201
We have presented a high resolution spectroscopy of Rb in magnetic field by far-detuning electromagnetically induced transparency (EIT). The EIT spectrum in the $\Xi$-type configuration is usually companied by a double resonance optical pumping (DROP) due to the strong optical coupling between the two upper states, leading to the spectral lines seriously deformed and widely broadened for complex relaxation processes in DROP. Here we demonstrate a high resolution spectroscopy by far-detuning EIT for $^{87}\rm{Rb}$ $\rm{5S_{1/2}\rightarrow5P_{3/2}\rightarrow5D_{5/2}}$ in magnetic fields. The method of far-detuning eliminates the relaxation in DROP to the most extent and decreases the spectral linewidth from more than 20 MHz down to its natural linewidth limit (6 MHz). The deformation of the spectral lines also disappears and the observed spectra are well in accordance with the theoretical calculation. Our work shows that far-detuning EIT is a reliable high resolution spectroscopic method when the relaxation in DROP cannot be neglected, especially for the case of transition to low excited states. 相似文献
10.
We study a simple, rational and C 2-cofinite vertex operator algebra whose weight 1 subspace is zero, the dimension of weight 2 subspace is greater than or equal to 2 and with c = c? = 1. Under some additional conditions it is shown that such a vertex operator algebra is isomorphic to ${L(\frac{1}{2},0)\otimes L(\frac{1}{2},0)}We study a simple, rational and C
2-cofinite vertex operator algebra whose weight 1 subspace is zero, the dimension of weight 2 subspace is greater than or equal
to 2 and with c = c̃ = 1. Under some additional conditions it is shown that such a vertex operator algebra is isomorphic to
L(\frac12,0)?L(\frac12,0){L(\frac{1}{2},0)\otimes L(\frac{1}{2},0)}. 相似文献
11.
Applying a recently developed evaporation technique for refractory elements the following results have been obtained for Ta181 in an atomic beam magnetic resonance experiment studying the hyperfine structure of 3 levels of the ground state multiplet4 F: $$\begin{gathered} g_J (^4 F_{3/2} ) = 0.45024 (4) \hfill \\ \Delta v (^4 F_{3/2} ;F = 5 \leftrightarrow F = 4) = 1822.389 (6) MHz \hfill \\ \Delta v (^4 F_{3/2} ;F = 4 \leftrightarrow F = 3) = 2325.537 (2) MHz \hfill \\ \Delta v (^4 F_{5/2} ;F = 6 \leftrightarrow F = 5) = 1451.476 (7) MHz \hfill \\ \Delta v (^4 F_{5/2} ;F = 5 \leftrightarrow F = 4) = 1537.530 (8) MHz \hfill \\ \Delta v (^4 F_{5/2} ;F = 4 \leftrightarrow F = 3) = 1444.685 (2) MHz \hfill \\ \Delta v (^4 F_{7/2} ;F = 4 \leftrightarrow F = 3) = 1218.372 (2) MHz. \hfill \\ \end{gathered}$$ From these measurements the following constants of the magnetic dipole interaction (A) and the electric quadrupole interaction (B) have been derived: $$\begin{gathered} A (^4 F_{3/2} ) = 509.0801 (8) MHz \hfill \\ B (^4 F_{3/2} ) = - 1012.251 (8) MHz \hfill \\ A (^4 F_{5/2} ) = 313.4681 (8) MHz \hfill \\ B (^4 F_{5/2} ) = - 834.820 (12) MHz. \hfill \\ \end{gathered}$$ 相似文献
12.
M. R. Setare D. Momeni V. Kamali R. Myrzakulov 《International Journal of Theoretical Physics》2016,55(2):1003-1018
We propose a generalised de Sitter scale factor for the cosmology of early and late time universe, including single scalar field is called as inflaton. This form of scale factor has a free parameter q is called as nonextensivity parameter. When q = 1, the scale factor is de Sitter. This scale factor is an intermediate form between power-law and de Sitter. We study cosmology of such families. We show that both kinds of dark components, dark energy and dark matter simultaneously are described by this family of solutions. As a motivated idea, we investigate inflation in the framework of q-de Sitter. We consider three types of scenarios for inflation. In a single inflation scenario, we observe that, inflation ended without any specific ending inflation ?end, the spectral index and the associated running of the spectral index are ns ? 1 ~ ?2??, αs ≡ 0. To end the inflation: we should have \(q=\frac {3}{4}\). We deduce that the inflation ends when the evolution of the scale factor is a(t) = e3/4(t). With this scale factor there is no need to specify ?end. As an alternative to have inflation with ending point, We will study q-inflation model in the context of warm inflation. We propose two forms of damping term Γ. In the first case when Γ = Γ0, we show the scale invariant spectrum, (Harrison-Zeldovich spectrum, i.e. ns = 1) may be approximately presented by (\(q=\frac {9}{10},~~N=70\)). Also there is a range of values of R and ns which is compatible with the BICEP2 data where \(q=\frac {9}{10}\). In case Γ = Γ1V(?), it is observed that small values of a number of e-folds are assured for small values of q parameter. Also in this case, the scale-invariant spectrum may be represented by \((q,N) = (\frac {9}{10},70)\). For \(q=\frac {9}{10}\) a range of values of R and ns is compatible with the BICEP2 data. Consequently, the proposal of q-de Sitter is consistent with observational data. We observe that the non-extensivity parameter q plays a significant role in inflationary scenario. 相似文献
13.
Fractional hyperfine density shifts (fds) for137Ba+ (I=3/2) ions are measured by means of direct optical pumping in noble gas buffers. The results for the fds (137Ba+, 6s 2 S 1/2) in units of 10?9/Torr (0 ?C) (measured at temperatures between 375 and 395 K) are: + 7(7) (He), ?74(8) (Ne), ?825(80) (Ar), ?1 500(200) (Kr), and < ?1600 (Xe). These shifts for the137Ba+ ion are considerably more negative than those for the isoelectronic137Cs atom. It is shown that this difference can be explained by taking into account the additional charge induced interaction. The hyperfine splitting frequency of the unperturbed137Ba+ 6s 2 S 1/2 state is extrapolated tov 0=8037741.6(6)kHz. 相似文献
14.
N. Vujičić S. Vdović D. Aumiler T. Ban H. Skenderović G. Pichler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):447-454
We present direct observation of the velocity-selective optical pumping of
the Cs ground state hyperfine levels induced by the femtosecond (fs) laser
oscillator centered at either D2 (6 2S1/2↦6 2P3/2,
852 nm) or D1 (6
P1/2, 894 nm) cesium
line. We utilized previously developed modified direct frequency comb
spectroscopy (DFCS) which uses a fixed frequency comb for the excitation and
a weak cw scanning probe laser centered at the 133Cs 6
2S1/2↦6 2P3/2 transition (D2 line) for ground
levels population monitoring. The frequency comb excitation changes the
usual Doppler absorption profile into a specific periodic, comblike
structure. The mechanism of the velocity selective population transfer
between the Cs ground state hyperfine levels induced by fs pulse train
excitation is verified in a theoretical treatment of the multilevel atomic
system subjected to a pulse train resonant field interaction. 相似文献
15.
We report on previously unobserved intersystem degeneracies in two-component equal-mass Fermi gases with interspecies zero-range interactions under isotropic harmonic confinement. Over the past 10 years, two-component Fermi gases consisting of n_{1} spin-up and n_{2} spin-down atoms with interspecies zero-range interactions have become a paradigm for modeling condensed matter systems, nuclear matter, and neutron matter. We show that the eigenenergies of the (n_{1}+1,n_{2}-1) system are degenerate with the eigenenergies of the (n_{1},n_{2}) system for any s-wave scattering length a_{s}, including infinitely large, positive, and negative a_{s}. The existence of the intersystem degeneracies is demonstrated explicitly for few-body systems with n_{1}+n_{2}=4, 5, and 6. The degeneracies and associated symmetries are explained within a group theoretical framework. 相似文献
16.
17.
Aaij R Abellan Beteta C Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Anderson J Appleby RB Aquines Gutierrez O Archilli F Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belogurov S Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R 《Physical review letters》2012,108(10):101803
We present a measurement of the time-dependent CP-violating asymmetry in B(s)(0) → J/ψ? decays, using data collected with the LHCb detector at the LHC. The decay time distribution of B(s)(0) → J/ψ? is characterized by the decay widths Γ(H) and Γ(L) of the heavy and light mass eigenstates, respectively, of the B(s)(0) - B(s)(0) system and by a CP-violating phase ?(s). In a sample of about 8500 B(s)(0) → J/ψ? events isolated from 0.37 fb(-1) of pp collisions at sqrt[s] = 7 TeV, we measure ?(s) = 0.15 ± 0.18(stat) ± 0.06(syst) rad. We also find an average B(s)(0) decay width Γ(s) ≡ (Γ(L) + Γ(H))/2 = 0.657 ± 0.009(stat) ± 0.008(syst) ps(-1) and a decay width difference ΔΓ(s) ≡ Γ(L) - Γ(H) = 0.123 ± 0.029(stat) ± 0.011(syst) ps(-1). Our measurement is insensitive to the transformation (?(s),ΔΓ(s)) ? (π - ?(s), -ΔΓ(s)). 相似文献
18.
Spectral property and its shape transition on 72—84Kr isotopes in microscopic core plus two—quasiparticle approach
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
By using a microscopic sdIBM-2+2q.p. approach, the levels of the ground-band, γ-band and partial two-quasi-particle bands for {}^{72-84}Kr isotopes are calculated. The data obtained are in good agreement with the recent experimental results, and successfully reproduce the nuclear shape phase transition of {}^{72-84}Kr isotopes at zero temperature. The ground-state band is described successfully up to J^π=18^+ and E_x=10.0MeV. Based on this model, the aligned requisite minimum energy has been deduced. The theoretical calculations indicate that no distinct change of nuclear states is caused by the abruptly broken pair of a boson, and predict that the first backbending of Kr isotopes may be the result of aligning of two quasi-neutrons in orbit g_{9/2}, which gains the new experimental support of the measurements of g factors in the {}^{78-86}Kr isotopes. 相似文献
19.
The electronic band structure of titanium dioxyde is calculated. The evolution of the levels and of the optical transitions under an uniaxial stress along the c axis has also been calculated.We confirm the existence, of a first order forbidden direct optical gap, and of a maximum along the Δ direction; the theoretical pressure coefficients ?E/?P for the Γ+7 → Γ+6 and Δ5 (max) → Γ+6 transitions are respectively 0.600 and 0.950 meV kbar-1 while the corresponding experimental values are 0.625 and 0.985 meV kbar-1. 相似文献
20.
The hyperfine structure of the 62 P 1/2 and 72 P 1/2 state of85Rb and87Rb and of the 62 P 3/2 state of87Rb has been investigated with optical double resonance at intermediate magnetic fields. The magnetic interaction constants,g j factors and lifetimes are: $$\begin{gathered} 6^2 P_{1/2} state: A\left( {^{85} Rb} \right) = 39.11\left( 3 \right) MHz,A\left( {^{87} Rb} \right) = 132.56 \left( 3 \right)MHz, \hfill \\ g_j = 0.6659\left( 3 \right), \tau = 1.14\left( {13} \right) \cdot 10^{ - 7} \sec , \hfill \\ 7^2 P_{1/2} state: A\left( {^{85} Rb} \right) = 17.68\left( 8 \right)MHz,A\left( {^{87} Rb} \right) = 59.92\left( 9 \right)MHz, \hfill \\ g_j = 0.6655\left( 5 \right), \hfill \\ 6^2 P_{3/2} state: g_j = 1.3337\left( {10} \right), \tau = 1.12\left( 8 \right) \cdot 10^{ - 7} \sec for ^{87} Rb. \hfill \\ \end{gathered} $$ From the hfs coupling constants of then 2 P multiplets a 11.5% core polarization contribution to the magnetic hfs of then 2 P 3/2 states is obtained, which is found to be independent from the main quantum numbern. The expectation values <r ?3> j for thenp valence electrons corrected for core polarization are compared with those derived from the2 P fine structure separation. Good agreement is achieved for allnp levels with the choice ofZ i =Z?3=34 for the effective nuclear charge number. The nuclear quadrupole moments of85Rb and87Rb are rederived on the basis of this more improved treatment for thep-electron-nucleus interaction yielding $$\begin{gathered} Q_N \left( {^{85} Rb} \right) = + 0.274\left( 2 \right) \cdot 10^{ - 24} cm^2 \hfill \\ Q_N \left( {^{85} Rb} \right) = + 0.132\left( 1 \right) \cdot 10^{ - 24} cm^2 \hfill \\ \end{gathered} $$ where the error does not include the remaining theoretical uncertainty of about 10%. 相似文献