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1.
A simple quark pair creation model is introduced to study exclusive decays of {c_J} into baryon-antibaryon pairs. With this simple model, some exclusive decay processes, for example, {c0} B¯ (B = ,0,-) are investigated and their decay widths are evaluated by inclusion of the properties of outgoing baryons, and the results show that the strengthened decay channels {c_J} ¯(J = 0, 2) are easily understood by considering only the color singlet contribution of P-wave charmonium.  相似文献   

2.
Using the CNDO/S method, we have performed quantumchemical calculations of the ground and excited electronic states of porphin molecules (symmetry D 2h ) and a number of porphin isomers: porphycene (C2h ), hemiporphycene, corphycene (C2v ), isoporphycene, and three nonsynthesized structural isomers of the porphin skeleton by its bridge groups —(CH) meso —. The results of the calculations are compared with the corresponding data for the freebase porphin molecule (H2P). Near the boundary between the occupied and vacant orbitals the isomers form rows of singleelectron levels with similar energy characteristics. For the MOs of these isomers, the H2P MOs closest in distribution on the comparable atomic centers are given. The weak (Q) and strong (B) transitions in the visible and near UV regions point to the porphyrin type of spectra of all the isomers. The calculation data on the excited electronic states of N, g, and ntype H2P near and above the B states are given; the presence of such states in other isomers is shown. The calculation does not point to a difference in the position of the first singlet transitions in the first five isomers. The calculation data on the lower singlettriplet transitions are also reported.  相似文献   

3.
Using the DFT/B3LYP method with the base set 631G**, we carried out calculation of the frequencies of the normal vibrations of porphin and of its five isotopic types. Scaling of force constants for outofplane vibrations has been performed in independent natural coordinates. The symmetry coordinates are introduced and a force field for outof plane vibrations of a porphin molecule in independent coordinates of symmetry is obtained. A new correlation of the frequencies of vibrations in the type of the symmetry B 1u for the isotopic type of the d 2 porphin molecule is suggested on the basis of discrete analysis of the distribution of a potential energy.  相似文献   

4.
A model of deterministic surface growth studied by Krug and Spohn, a model of the annihilating reactionA+Binert studied by Elskens and Frisch, a one-dimensional three-color cyclic cellular automaton studied by Fisch, and a particular automaton that has the number 184 in the classification of Wolfram can be studied via a cellular automaton with stochastic initial data called ballistic annihilation. This automaton is defined by the following rules: At timet=0, one particle is put at each integer point of . To each particle, a velocity is assigned in such a way that it may be either +1 or –1 with probabilities 1/2, independent of the velocities of the other particles. As time goes on, each particle moves along at the velocity assigned to it and annihilates when it collides with another particle. In the present paper we compute the distribution of this automaton for each timet . We then use this result to obtain the hydrodynamic limit for the surface profile from the model of deterministic surface growth mentioned above. We also show the relation of this limit process to the process which we call moving local minimum of Brownian motion. The latter is the processB x min ,x , defined byB x min min{B y ;x–1yx+1} for everyx , whereB x ,x , is the standard Brownian motion withB 0=0.  相似文献   

5.
From analysis of anisotropical lattice bands properties of 50 reflection spectra both of the CO stretching and bending bands measured from some pearl (Ca++CO 3 –– or Ca++HCO 3 –– layer) we discussed following subjects.i) Quantized properties present both in reflectivity and in energy. ii) classifications of the Optical Activity. iii) Polar distributions of the CO3 oscillators in Ca++CO 3 –– surface mono-layer. iv) Force constants of these oscillators. v) Step variation of the dipolemoment and their influences to the degree of Optical Activity. vi) Two types of hysteresis loops of the values of YN (M2Jbend ()/M1Jstret. ()) derived from the oscillators which are at innert-state, at weak active-state and at active-state.  相似文献   

6.
Faceting is a well documented phenomenon known both for surfaces and interfaces, particularly, grain boundaries (GBs). Faceting can be considered as a phase transition when the original surface or GB dissociates onto flat segments whose energy is less than that of the original surface or GB. For the investigation of GB faceting a cylindrical Cu bicrystal with an island grain was grown by the Bridgman technique. Grain 1 in this bicrystal is completely surrounded by grain 2. The dissociation 9 3 + 3 proceeds during the growth of the bicrystal. The twins appear instead of {111}1/{115}2 or (110)9CSL facet. GB faceting was studied at 1293 K, 1073 K, and 873 K. The profiles of the GB thermal groove were analysed by atomic force microscopy. Wulff-Herring plots and GB phase diagrams have been constructed for the 3, 9 and 9 + 3 GBs. With increasing temperature the facets with low-density CSL-planes disappear in the GB shape. GB roughening phase transition can be responsible for this phenomenon.  相似文献   

7.
We construct explicitly three-dimensional localized solutions of the free Maxwell's equations with a phase expi(k x - t) which move like relativistic particles. The total field energyE of the moving lump is proportional to the frequency and its momentumP is proportional to the wave vectork, withE 2 =P 2 +M 2. Further, if the angular momentum is different from zero, thenE =. These solutions thus model the wave-particle duality of quantum particles.  相似文献   

8.
Resonance Raman spectra (RRS) of Co(II) and Co(III)5,10,15,20tetrakis(4Nmethylpyridinium)porphyrin ((CoII(TmpyP4), and CoIII(TMPyP4)) in aqueous solutions at different pH as well as in organic solvents (methanol, ethanol, DMSO, DMF) are obtained. The increased sensitivity of the oscillation frequencies 2, 4, 8, and 6 — the markers of the oxidation state of a metal — to the nature of an axial ligand has been revealed. For CoIII(TmpyP4), the shifts of the indicated frequencies in extracoordination have turned out to be twofold larger than those for CoII(TmpyP4). The spectral effects observed are related to different electron influence of the extraligands on the system of the porphyrin ring. In the case of Co(III)porphyrin, interaction of the d orbitals of the metal and the e g *orbitals of the macrocycle is more efficient since its ionic radius is smaller than for the Co(II)complex. For CoIII(TmpyP4), a linear correlation between the oscillation frequencies 2, 4, 8, and 6 and the experimental Gutmann parameters characterizing the electronacceptor properties of solvents is found.  相似文献   

9.
Dark resonances in the 154Sm -system 4f 66s 2(7 F 0) 4f 66s6p(9 F 1 0) 4f 6 s 2(7 F 1) are observed alongside the velocity selective optical pumping. The shape of the resulting spectra strongly depended on the buffer gas (He, Ar) pressure due to velocity-changing collisions (VCC): the sign of the effect could be reversed from the dark to the bright resonance. The observed spectra are interpreted within the framework of the hard-sphere collision model. The role of VCC in the formation of the dark state in the -system is discussed.  相似文献   

10.
Within the framework of the method of a density matrix, differential equations are obtained that describe the evolution of the modes of magnetization <Î+>, <Î+ z >, and <Î+ z 2> for a spin system containing a nucleus with a 1/2 spin connected scalarly with the quadruple nucleus of the spin S = 1 in the presence of crosscorrelation between the dipole ISinteractions, anisotropy of the chemical shift of the I and S nuclei, and quadruple interaction of the S nucleus. The equations are used for analysis of the evolution of the intensities of each line in the triplet of the Raman spectrum of the 1/2 spin. Expressions for the times of crossrelaxation and the times of transverse relaxation of each of the lines of the triplet are obtained.  相似文献   

11.
The two-neutrino positron double-beta decay of 106Cd for the 0 + 0+ transition has been studied in the Hartree-Fock-Bogoliubov model in conjunction with the summation method. In the first step, the reliability of the intrinsic wave functions of 106Cd and 106Pd nuclei has been tested by comparing the theoretically calculated results for yrast spectra, reduced B(E2: 0+ 2+) transition probabilities, quadrupole moments Q(2+) and gyromagnetic factors g(2+) with the available experimental data. In the second step, the nuclear transition matrix element M2 and the half-life T1/22 for the 0 + 0+ transition have been calculated with these wave functions. Moreover, we have studied the effect of deformation on the nuclear transition matrix element M2.  相似文献   

12.
A method is suggested for the derivation of finite-size corrections in the thermodynamic functions of systems with pair interaction potential decaying at large distancesr asr d , whered is the space dimensionality and>0. It allows for a unified treatment of short-range (=2) and long-range (<2) interaction. The asymptotic analysis is illustrated by the mean spherical model of general geometryL d–d× d subject to periodic boundary conditions. The Fisher-Privman equation of state is generalized to arbitrary real values ofd, 0d. It is shown that the-expansion may be used to study the breakdown of standard finite-size scaling at the borderline dimensionalities.  相似文献   

13.
14.
Using field-theoretic arguments for self-avoiding walks on dilute lattices with site occupation concentrationp, we show that the-point size exponent p 0 of polymer chains remains unchanged for small disorder concentration (p>p c ). At the percolation thresholdp=p c , using a Flory-type approximation, we conjecture that pc 0 =5/(d B +7), whered B is the percolation backbone dimension. It shows that the upper critical dimensionality for the-point transition atp=p c shifts to a dimensiond c >3. We also propose that the-point varies practically linearly withp for 1>pp c .  相似文献   

15.
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Stability of a glow discharge in small currents
Two approximations of the dynamic characteristic of a glow discharge for small currents are derived. In the first approximation only the influence of the rate of rise and decay of charge carriers in the delay process is accounted for. In the second approximation, the influence of the rate of stabilization of the radial electric field in the discharge is added. On the basis of the derived equations the conditions for the simplest stability of the discharge are calculated. A comparison with experiment gives satisfactory results.


. . . . .  相似文献   

16.
EC and decays of 235Am have been studied using a gas-jet coupled on-line isotope separator. Excited states in 235Pu have been established for the first time by means of -ray spectroscopy following the EC decay of 235Am. The deduced log ft value suggests that the ground state of 235Am should have the 5/2-[523] configuration. The - coincidence result has revealed that the 5/2-[523] state in 231Np populated by the favored transition of 235Am is located at < 15 keV, which allows us to precisely determine the Q value of 235Am.  相似文献   

17.
The collective structures of 131Cs have been investigated by in-beam -ray spectroscopic techniques following the 124Sn (^11B , 4n) reaction at a beam energy Elab = 57MeV. The previously established rotational bands, built on g7/2, d5/2 and the unique-parity h11/2 orbitals, have been extended and evolve into new bands involving rotationally aligned (h11/2)2 and (h11/2)2 quasiparticles. In addition, a new multiquasiparticle band based on the g7/2 g7/2 h11/2 configuration has also been observed. Theoretical interpretations for the assigned configurations are discussed in the framework of Total Routhian Surface (TRS) and Tilted Axis Cranking (TAC) model calculations. TAC model calculations predict a decrease in the B(M1) values with increasing rotational frequency for the g7/2/d5/2 (h11/2)2 and h11/2 (h11/2)2 bands, thus indicating a magnetic rotation character for these bands.  相似文献   

18.
The fluctuations in limit cycles of second-order bifurcation (transition from a stable to an unstable focus) are investigated near the bifurcation point c, being an external control parameter. Two different methods are applied: a time- and space-dependent Fokker-Planck equation obtained from an 1/2-expansion of the master equation ( being the volume) and a time- and space-dependent Langevin equation. Both methods give the same results. It is shown that the dependence of the radial correlation on 2 = | – c| and the time-behaviour of the phase correlation (ensemble dephasing) are determined by the dimensionality of space.  相似文献   

19.
20.
A new theory of rectangular coils without an iron core is described which amends the old one of Fabry and Bitter. It enables us to compute field intensities in coils having very small openings, which the old theory could not do.
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