(e,e′), (γ, π+ and (π−, γ) on12C and13C

A detailed theoretical analysis of spin degrees of freedom in carbon isotopes is performed, probing them by electron scattering, pion photoproduction and radiative pion capture from the mesoatomic orbits.Dedicated by the co-authors to the memory of J. Gmitro.The present paper is one of the last works made together with our colleague Marian Gmitro. We had to complete it without him. We mourn for his sudden death and we will always keep alive the memory of his bright personality.     

Cooperative effects between F … Ag bonded and X … Br (Cl) halogen-bonded interaction in BrF(ClF) … AgX … BrF(ClF) (X = F,Cl, Br) complexes: a theoretical study

The equilibrium structures, interaction energies and binding properties of ternary BrF(ClF)?… AgX?…?BrF(ClF)(X?=?F, Cl, Br) complexes and the corresponding binary systems have been studied by DFT method at the X3LYP/aug-cc-pVQZ level. Cooperative effects are probed by analysing charge transfer, electronic properties and orbital interactions when F?…?Ag bond and X?…?Br (Cl) halogen bond coexist in the same complex. The results indicate that the X?…?Br (Cl) halogen bond has a greater enhancing effect than the F?…?Ag bond does, resulting in a shorter binding distances, larger interaction energies and greater electron densities for the ternary complexes than for the corresponding binary ones. In addition, the origins of both the F?…?Ag bond and X?…?Br (Cl) halogen bond have been deduced via energy decomposition.     

InSb(211)A,B表面电子结构特性

采用散射理论的格林函数方法计算了InSb(211)A,B两类表面的电子结构,分别给出了两类表面的表面投影能带结构,分析了各表面态的轨道特性和色散特性;并在此基础上讨论了两类表面的稳定性;计算结果和实验结果定性的相符合. 关键词：     

Sc12X团簇(X=B,C,N,Al,Si,P)的电子结构和稳定性

基于第一性原理,在密度泛函理论框架下,用广义梯度近似(GGA)研究二十面体Sc12X(X=B、C、N、Al、Si、P)中性和荷电团簇的电子结构和稳定性,系统计算了它们的基态束缚能(BE)、原子间平衡间距、最高占据轨道(HOMO)与最低占据轨道(LUMO)之间的能隙、局域电荷以及HOMO电子构型.研究表明,用C、Si原子或荷电后的B、N、Al、P离子分别替代团簇Sc13中心原子可以使其成为稳定的结构.Sc12X团簇束缚能改变的原因在于掺杂改变了中心原子或离子与表面原子的轨道杂化.     

A study of the 29,30Si(α, d)31,32P and the 29,30Si(d, α)27,28 Al reactions

The ${}^{\mathrm{29,30}}\text{Si}\text{(α,}\text{d}\text{)}{}^{\mathrm{31,32}}\text{P}$ reactions have been studied at a beam energy of 25 MeV and the ${}^{\mathrm{29,30}}\text{Si}\text{(}\text{d}\text{, α)}{}^{\mathrm{27,28}}\text{Al}$ reactions have been studied using a 12.3 MeV tensor polarised deuteron beam. The data have been analysed using the microscopic DWBA. Three representations of the nucleon-nucleon interaction have been compared by incorporating the appropriate spectroscopic amplitudes for two nucleon transfer obtained from shell model calculations, in the microscopic form factor.     

Benford’s law and cross-sections of A(n,$ \alpha$)B reactions

Benford’s law, also called the first-digit law, states that in lists of numbers from many quite disparate databases, the leading digit is distributed in a non-uniform but actually logarithmic way. We have investigated the first-digit distribution of experimental cross-sections of A(n,a \alpha)B reactions. In the case of below-barrier a \alpha -particle emission from compound nucleus, it is found that the (n,a \alpha) reaction cross-sections approximately follow the first-digit distribution indicated by Benford’s law. The origin of this first-digit distribution is discussed within the framework of the statistical model. In addition, Benford’s law is used to test the evaluated cross-sections of A(n,a \alpha)B reactions.     

The diphenylphosphino radical, (C6H5)2˙P

The diphenylphosphino radical, (C₆H₅)₂P, has been observed at room temperature in X-irradiated single crystals of triphenylphosphine oxide and diphenylphosphine sulphide and in ultra-violet irradiated polycrystalline diphenylphosphine at 77 K. The isotropic ³¹P coupling constant is deduced to be +252 MHz and the anisotropic components are approximately 504, -252, -252 MHz. The largest value of the g tensor lies perpendicularly to the direction of the largest hyperfine coupling constant, the values in diphenylphosphine sulphide being 2·0094, 2·0035 and 2·0021. X-irradiated triphenylphosphine oxide also contains the (C₆H₅)₂PO radical.     

Predicting lepton flavor mixing from Δ(48) and generalized C P symmetries

We propose to understand the mixing angles and C P-violating phases from the ?(48) family symmetry combined with the generalized C P symmetry. A model-independent analysis is performed by scanning all the possible symmetry breaking chains. We find a new mixing pattern with only one free parameter, excellent agreement with the observed mixing angles can be achieved and all the C P-violating phases are predicted to take nontrivial values. This mixing pattern is testable in the near future neutrino oscillation and neutrinoless double-beta decay experiments.Finally, a flavor model is constructed to realize this mixing pattern.     

Wild Rabbit Host and Some Parasites Show Trophic-Level Relationships for δ(13)C and δ(15)N: A First Report

Abstract We report the first isotopic study of an animal host-parasite system. Parasitic, intestinal nematodes, Graphidium strigosum and Passalurus ambiguus, were (15)N-enriched relative to their host, the European rabbit Oryctolagus cuniculus, while parasitic cestodes, Cittataenia denticulata and Mosgovoyia pectinata, were (15)N-depleted, suggesting different trophic relationships. Host embryos were more similar in their δ(13)C and δ(15)N values to maternal muscle than were any of the parasites. Coprophagy, the direct recycling of food by the rabbit eating its own faeces, did not lead to isotopic differences between stomach contents and faeces, suggesting that the major point for isotopic discrimination in lagomorph nitrogen metabolism is in the animal rather than in the gut. We conclude that bulk δ(13)C and δ(15)N can reveal valuable new information about host-parasite relationships, and these could be explored further at the biochemical level using compound-specific isotopic analyses.     

A classification of quantum GL(2,C)’s

We show that the two-parameter standard quantum GL(2, C) (except for roots of unity) and the Jordanian quantum GL(2, C) have the “same” representation theory as the (ordinary) group GL(2, C), and that they are the only quantum groups with this property. Presented at the 9th Colloquium “Quantum Groups and Integrable Systems”, Prague, 22–24 June 2000.     

Strong decays of χcJ(2P) and χcJ(3P)

In the framework of the chiral quark model, the mass spectrum of χ _cJ (J = 0, 1, 2, n = 1, 2, 3) is studied with the Gaussian expansion method. Using the wave functions obtained in the study of mass spectrum, the open charm two-body strong decay widths of these states are calculated by using the ³ P ₀ model. The results show that the masses of χ _cJ (1P) and χ _c2(2P) are consistent with the experimental data. But the strong decay width of χ _c2(2P) is three times that of the experimental value. The decay width of χ _c1(2P) is sensitive to its mass. In the quark-antiquark picture, the width is about 385 MeV. However, if the channel coupling effects shift its mass to 3872 MeV, its decay width will be around 1 MeV. The possibility of assigning the state X(3872) as χ _c1(2P) cannot be excluded. To assign X(3915) as χ _c0(2P) is disfavored, due to the unmatching of decay channel. For the χ _cJ (3P) states, no states have been assigned. The possible candidates of χ _c0(3P) are X(4160) and X(4140). Their masses are close to the theoretical ones. The experimental branching ratio of X(4160), $\Gamma (X(4160) \to D\bar D)/\Gamma (X(4160) \to D*\bar D*) < 0.09$ is compatible with that of χ _c0(3P), 0.07. However the broad decay width of X(4160) cannot be explained by the open charm two-body decay. To assign X(4140) as χ _c0(3P) is also possible, due to the compatibility of the total decay width, the further measurement of decay modes of X(4140) are expected to justify the assignment.     

Electron spin resonance spectrum of radicals in γ-irradiated trimethyl phosphite: P(OMe)4, HP(OMe)3, P(OMe)2, (MeO)3P-P(OMe)3 + and H2COP(OMe)2

The infra-red spectra of 1 : 1 complexes between benzene and chlorine, bromine, and iodine chloride have been studied, with the complexes isolated in a nitrogen matrix at 20 K. The results are interpreted as evidence for an oblique complex structure, with the halogen molecule interacting mainly with one of the C=C bonds.     

~(186)W(d,p)~(187)W,~(186)W(d,2n)~(186)Re,~(nat)Fe(p,x)~(56)Co和~(nat)Ti(a,x)~(51)Cr反应激发函数评价

考虑特征γ射线分支比、衰变常数和标准截面等修正,对带电粒子引起的核反应~(186)W(d,p)~(187)W,~(186)W(d,2n)~(186)Re,~(nat)Fe(p,x)~(56)Co和~(nat)Ti(a,x)~(51)Cr的激发函数进行了研究。全面收集了这些反应激发函数的实验测量数据,对这些实验数据进行了分析处理,应用数学方法对分析处理后的实验数据进行了拟合。经过评价,给出了50 Me V以下~(186)W(d,p)~(187)W,~(186)W(d,2n)~(186)Re,~(nat)Fe(p,x)~(56)Co和~(nat)Ti(a,x)~(51)Cr反应激发函数的推荐值。     

Review of magnetic features observed in (A,A′)Ni2B2C solid solutions

The nickel-borocarbides ANi₂B₂C [A=Y, Ln (lanthanide), An(actinide)], crystallizing in the body-centred tetragonal LuNi₂B₂C-type structure, are classified according to the existence or coexistence of superconducting and antiferromagnetic states (AF). The magnetic features observed in polycrystalline (A,A′)Ni₂B₂C solid solutions, adopting the same crystal structure, are reviewed and discussed. Published data on the magnetism in (A,Ln)Ni₂B₂C systems (ANi₂B₂C nonmagnetic, A=Y,La,Lu) indicate a gradual rise in the threshold content, x(m), in (Y_1−xLn_x)Ni₂B₂C (Ln=Gd,Tb,Dy,Ho,Er) for the establishment of AF states. (A,A′)Ni₂B₂C systems with magnetic end compounds show gradual variation in magnetic features when A and A′ are both heavy Ln. The behaviour of (A,A′)Ni₂B₂C systems of light A (Pr or U) and heavy A′ (Dy or Tm) depends on the magnetic structures of the end compounds. In intermediate compositions, incomplete moment compensation in (Pr,Dy)Ni₂B₂C decreases T_N, while different moment directions in the end compounds in (U,Dy)Ni₂B₂C lead to a directional frustration of ordered moments. Such a frustration in (U,Tm)Ni₂B₂C is related to different magnetic structures of the end compounds.