电子碰撞分子的R-矩阵研究

采用R-矩阵方法首次研究了电子碰撞激发S3分子过程.S3分子靶态采用24个电子态密耦合表示,计算了电子碰撞由基态1A1平衡位置垂直激发到电子激发态13B2,13B1,13A2,11A2和11B1的积分散射截面.     

Reduction of the Lane-Robson “calculable” reaction theory to standard R-matrix form

General dynamical equations derived from the Lane-Robson calculable reaction formalism are cast into a form amenable to standard R-matrix treatment, permitting the resonance content of the equations to be made explicit. Formulae are given which enable the collision matrix and the amplitudes of physical eigenfunctions to be calculated directly from the R-matrix with or without the isolation of resonance contributions. The present methodology permits a significant reduction of effort in numerical investigations of the energy dependence inherent in dynamical models of the nucleus. The formalism is illustrated by calculational results obtained from a potential model fitted to ¹⁶O + n scattering data.     

Electron-molecule collisions at low and intermediate energies using the R-matrix method

We present the latest developments of the R-matrix method as applied to electron-molecule collisions. A variety of calculations for H₂O are presented including the study of rotational excitation and preliminary data for dissociative electron attachment. Results for the application of the recently developed molecular R-matrix with pseudostates (MRMPS) method to neutral and cationic targets are also included. This method is currently being applied to the study of collisions with anionic targets.     

Microscopic R-matrix theory in a generator coordinate basis: (III). Multi-channel scattering

The microscopic R-matrix theory presented in two previous papers is extended to the multichannel scattering case. An antisymmetrized wave function is built in the two-centre harmonic oscillator model. This wave function is proved to be equivalent to the resonating group one even if the nuclei have non-zero spin. The method only requires the calculation of numerical values of matrix elements between Slater determinants. The microscopic R-matrix theory may be applied to study both reactions and inelastic scattering.     

Electron collisional excitation of argon-like Ni XI using the Breit-Pauli R-matrix method

Electron excitation collision strengths for the transitions from the ground state to the fine-structure levels of the 3s²3p⁵3d and 3s²3p⁶3d configurations in Ni XI are calculated using the Breit-Pauli R-matrix method. Configuration interaction wavefunctions have been used to represent the target states. The relativistic effects are incorporated in the Breit-Pauli approximation by including one-body mass correction, Darwin, and spin-orbit interaction terms in the scattering equations. Collision strengths are tabulated at selected energies in the range 10 to 75 Rydberg. Effective collision strengths are determined by integrating collision strengths by assuming a Maxwellian distribution of electron energies. The effective collision strengths are listed over a wide temperature range (2×10⁴-1×10⁷ K) applicable to astrophysical plasmas. Our results are the only collision strengths and effective collision strengths available for this ion. We believe that the data calculated in this work will be useful in solar, astrophysical and laser applications.     

A generalization of Wigner's R-matrix method

A generalization of the Wigner's non-relativistic R-matrix theory of scattering by a central potential field is proposed. The idea is to use an R-matrix expansion basis generated by a Sturm-Liouville problem with an eigenparameter included both in a differential equation and in a boundary condition (in the standard theory an R-matrix basis is obtained by solving an eigenvalue problem with fixed boundary conditions). A partial fraction expansion of an R^(η)-matrix introduced is derived and shown to converge faster than a partial fraction expansion of Wigner's R-matrix used in the standard theory.     

“Electron collisional excitation of argon-like Ni XI using the Breit-Pauli R-matrix method”

In a recent paper, Verma et al. [Eur. Phys. J. D 42, 235 (2007)] have reported results for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 17 levels of the (1s²2s²2p⁶)3s²3p⁶, 3s²3p⁵3d and 3s3p⁶3d configurations of Ni xi. They adopted the civ3 and R-matrix codes for the generation of wavefunctions and the scattering process, respectively. In this paper, through two independent calculations performed with the fully relativistic darc (along with grasp) and fac codes, we demonstrate that their results are unreliable. New data are presented and their accuracy is assessed.     

A new general R-matrix theory of collinear reactions and its application to the H + H2 reaction

A new general R-matrix theory of collinear reactions is developed by using the polar coordinate for the inner interaction region and the Cartesian coordinate for the two outer (reactants and products) asymptotic regions. The theory is applied to the collinear H + H₂ exchange reaction.     

Electron impact excitation collision strengths for neon-like Ni XIX calculated using the relativistic R-matrix method

In a recent paper [Pramana — J. Phys. 64, 129 (2005)] results have been presented for electron impact excitation collision strengths for transitions among the fine-structure levels of the 2s²2p⁶ and 2s²2p⁵3s configurations of Ni XIX. In this paper we demonstrate through an independent calculation with the relativistic R-matrix code that those results are unreliable and the conclusions drawn are invalid.     

Baxterization of Solutions to Reflection Equation with Hecke R-matrix

Let R be a Hecke solution to the Yang–Baxter equation and K be a reflection equation matrix with coefficients in an associative algebra . Let R(x) be the baxterization of R and suppose that K satisfies a polynomial equation with coefficients in the center of . We construct solutions to the reflection equation with spectral parameter relative to R(x), in the form of polynomials in K.     

Baxter Q-operators of the XXZ chain and R-matrix factorization

We construct Baxter operators as generalized transfer matrices being traces of products of generic R matrices. The latter are shown to factorize into simpler operators allowing for explicit expressions in terms of functions of a Weyl pair of basic operators. These explicit expressions are the basis for explicit expression for Baxter Q-operators and for investigating their properties.     

Raman spectroscopic probing of plant material using SERS

We report surface‐enhanced Raman studies on intact plant material using onion layers as a biological target, and silver nanoaggregates and silver island films as enhancing plasmonic structures. Surface‐enhanced Raman scattering (SERS) enhancement allows the detection of strong Raman signatures of chemical constituents of the surface of the onion layer such as cellulose, proteins, and flavonols. Because of long‐time incubation, SERS sensors can access the extracellular space in the inner of the layer. The location of silver nanoparticles inside the onion layer has been monitored by the SERS images collected from chemicals present in the onion and/or reporter molecules attached to the nanoparticles. Our studies show a competitive adsorption of intrinsic bio molecules of the onion layer and reporter molecules. Different spectra from different places of the layer indicate the complex heterogeneous chemical structure of the plant material. The pH‐sensitive reporter molecule para mercapto benzoic acid attached to the nanoparticles allows us to infer pH values inside the extracellular matrix of the onion layer. Copyright © 2015 John Wiley & Sons, Ltd.     

Morphology of InN nanorods using spectroscopic Raman imaging

We report the vibrational properties of vertical and oblique InN nanorods (NRs) grown by molecular beam epitaxy (MBE). Surface optical (SO) Raman mode at 561 cm⁻¹, belonging to E₁ symmetry [SO(E₁)], is identified along with symmetry allowed Raman modes of E₂(low), E₂(high), and E₁(LO) at 87, 489, and 589 cm⁻¹, respectively, corresponding to wurtzite InN phase. Usually, SO phonon modes arise due to breakdown of translational symmetry of surface potential at surface defects, which are attributed by the surface roughness. Intensity distribution of E₁(LO) and SO(E₁) phonon modes over a specified area have been analysed using Raman area mapping with an optical resolution of 400 nm. Imaging with E₁(LO) phonon mode, originating from the bulk of the sample, distinguishes the vertical NRs alone. We are able to resolve NR morphologies in both vertical and oblique cases with additional Raman mapping analysis of SO(E₁) phonon mode, emerging from the surface irregularities, which are confined to the tip of MBE grown NRs. Copyright © 2013 John Wiley & Sons, Ltd.     

Proton spectroscopic factors of Sm isotopes in the pairing-plus-quadrupole model

Proton spectroscopic factors have been calculated for the single-proton states in Sm isotopes with N = 84–92 by using the deformed quasiparticle wave functions obtained in the pairing-plus- quadrupole model. Comparison is given with the experimental data from the pick-up reactions (d, ³He) and (t, ⁴He) to the product nuclei ^145–153Pm. Effects of deformation on the spectroscopic factors are studied.     

Quenching of spectroscopic factors for proton removal in oxygen isotopes

We present microscopic coupled-cluster calculations of the spectroscopic factors for proton removal from the closed-shell oxygen isotopes (14,16,22,24,28)O with a chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order. We include coupling-to-continuum degrees of freedom by using a Hartree-Fock basis built from a Woods-Saxon single-particle basis. This basis treats bound and continuum states on an equal footing. We find a significant quenching of spectroscopic factors in the neutron-rich oxygen isotopes, pointing to enhanced many-body correlations induced by strong coupling to the scattering continuum above the neutron emission thresholds.     

R-matrix plus potential analysis of unbound states of33S

Single channel single levelR-matrix plus potential analysis of the resonances observed in the³²S(n, n) reaction for the neutron energy lying from 20–1100 keV has been carried out to determine the properties of these resonances. This analysis is further supported by a single channel multilevelR-matrix analysis of the data. Spectroscopic factors for the resonances have also been calculated by ourR-matrix method. Its comparison with those obtained bydwba analysis of the (d, p) data is discussed.     

Relativistic R-matrix close-coupling calculations for photoionization of Ne-like Al IV

We present relativistic close-coupling photoionization calculations of Al IV using the Breit-Pauli R-matrix method to obtain photoionization cross-section of Al IV from the ground state and the lowest two J=0 (even) excited states. A multi-configuration eigenfunctions expansion of the core Al V is employed with spectroscopic configurations 2s²2p⁵, 2s2p⁶, 2s²2p⁴3s, 2s²2p⁴3p, 2s²2p⁴3d and 2s²2p⁴4s. We have included, for the first time, the lowest 68 level target states of Al V in the photoionization calculations of Al IV. Extensive configuration interaction wavefunctions are used to describe both the initial Al IV states and the final Al V states. Cross-sections are compared from three level calculations including only 2s² 2p^{5 2}P^o _3/2, _1/2 and 2s 2p^{6 2}S_1/2 levels of Al V. The present calculation using the lowest 68 target levels of Al V are presented for the first time and should provide reasonably complete database for practical application for photoionization cross-section for Al IV, where high-energy cross-sections along with near-threshold photoionization cross-section is required.     

Electron impact excitation of Ni-like gold studied by Dirac R-matrix method

We calculate the electron impact excitation of Ni-like gold by using the Dirac R-matrix theory, and the corresponding collision strengths and effective collision strengths are obtained. In the calculations of the level energy,(1s22s22p6)3s23p63d10, 3s23p63d94 l, 3s23p53d104 l, and 3s3p63d104l(l = 0,1,2,3) configurations are included and 107fine-structure levels are generated. In the calculations of the collision strengths, only the first 59 levels are included. Comparisons are made with the distorted wave(DW) results of Zeng et al. for both collision strengths and effective collision strengths. For the collision strengths, the two sets of calculations are in excellent agreement for most of the transitions.However, because of the inclusion of the resonances, our effective collision strengths are generally several times larger than those of Zeng et al.. The accuracy of our calculations is assessed.     

Time resolved spectroscopic NMR imaging using hyperpolarized Xe

We have visualized the melting and dissolution processes of xenon (Xe) ice into different solvents using the methods of nuclear magnetic resonance (NMR) spectroscopy, imaging, and time resolved spectroscopic imaging by means of hyperpolarized ¹²⁹Xe. Starting from the initial condition of a hyperpolarized solid Xe layer frozen on top of an ethanol (ethanol/water) ice block we measured the Xe phase transitions as a function of time and temperature. In the pure ethanol sample, pieces of Xe ice first fall through the viscous ethanol to the bottom of the sample tube and then form a thin layer of liquid Xe/ethanol. The xenon atoms are trapped in this liquid layer up to room temperature and keep their magnetization over a time period of 11 min. In the ethanol/water mixture (80 vol%/20%), most of the polarized Xe liquid first stays on top of the ethanol/water ice block and then starts to penetrate into the pores and cracks of the ethanol/water ice block. In the final stage, nearly all the Xe polarization is in the gas phase above the liquid and trapped inside the pores. NMR spectra of homogeneous samples of pure ethanol containing thermally polarized Xe and the spectroscopic images of the melting process show that very high concentrations of hyperpolarized Xe (about half of the density of liquid Xe) can be stored or delivered in pure ethanol.