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We present detailed studies on the differential cross section (DCS) and total cross section (TCS) in electron–alkali-atom collision processes by using two types of distorted wave methods, the ordinary distorted wave method and the indirect-relativistic distorted wave method. We find that the indirect relativistic effect in the target atom can be neglected in the TCS calculation in the processes; however, with an increase of the atomic number, this effect becomes significant in the DCS calculation. Then, based on the density matrix theory, the orientation and alignment parameters of excited caesium P states scattered by electrons at low incident energy are calculated, and comparisons are made for the two series between the two methods. The results show that accordance is reached at scattering angles smaller than 45°, but considerable difference appears at angles larger than 45° due to the relativistic effect.

The equilibrium geometry, harmonic frequency and bond dissociation energy of lanthanum monofluoride have been calculated using Density-Functional Theory (DFT), post-HF methods MP2 and CCSD(T) with the energy-consistent relativistic effective core potentials. The possible electronic state and reasonable dissociation limit of the ground state of LaF are determined based on atomic and molecular reaction statics. Potential energy curve scans for the ground state X1Σ+ have been performed at B3LYP and CCSD(T) levels, due to their better results of harmonic frequency and bond dissociation energy. We find that the potential energy calculated with CCSD(T) is about 0.6 eV larger than the bond dissociation energy, when the internuclear distance is as large as 0.8 nm. The problem that single-reference ab initio methods do not meet dissociation limit during calculations of lanthanide heavy-metal elements is analyzed. We propose the calculation scheme to derive the analytical Murrell-Sorbie potential energy function. Vibrotational spectroscopic constants Be, ωe, ωeχe, αe, βe, De and He obtained by the standard Dunham treatment coincide well with the results of rotational analyses on spectroscopic experiments.

In this paper, we present the research on an optical electron polarimeter, which is used to determine the polarization of an incident electron beam by measuring the relative Stokes parameters of the fluorescence emitted from the He gas following the impact excitation with the electron beam. The fundamental theory of the optical electron polarimeter is discussed with the 33P→23S transition of He. The structure and performance of the instrument are described, which are different in some aspects from previous works. The arrangement of the experiment for measuring the relative Stokes parameters of linearly polarized weak light is also investigated, which actually involves the same processes as the polarization measurement with the incident electron beam. The results obtained are in agreement with the theoretical prediction.

A laser ion source based on laser resonant ionization at the outlet of a helium jet was proposed for on-line isotope separator of the Heavy Ion Research Facility in Lanzhou, China a few years ago. An off-line test setup was built at Tsinghua University. The initial experimental results of the setup indicate that carrying neutral Na monoatoms to the outlet of a helium jet and directly ionizing the Na atoms in the helium jet beam by laser resonant ionization is very efficient. It provides an effective method for producing element selected ions with high efficiency, low background, and short transporting time. It is applicable for the separation of various elements, and is particularly useful for refractory elements.

The polarization of spin-polarized electrons, produced from a new GaAs spin-polarized electron source, is determined by an optical electron polarimeter. The He 3 3P→23S1 (388.9 nm) transition is used for the optical electron polarimetry. The structure and performance of the experimental setup of spin-polarized electron source and optical electron polarimeter are described. The result of polarization of 30.8% averaged spin-up and spin-down polarized electrons is obtained and presented.

Integrated Stokes parameters Pi (i = 1,2,3) for the He 3 3P→2 3S1 (388.9 nm) transition after excitation from the ground state to the 3 3P state by a transversely spin-polarized electron beam are measured in near threshold energy region. The experimental results are presented. The linear-polarization P2 are consistent with zero over the incident energy range, providing evidence for the LS coupling mechanism of the 3 3P state. The measured circular polarization P3 are non-zero, indicating strong electron-electron exchange effects in the spin-polarized electron-atom collision process.

The observable quantities (Stokes parameters, orientation parameter L⊥+, alignment angle γ, linear-light-polarization degree Plin) of rubidium, excited from S to P and scattered by electrons at 20 eV, are calculated with the two distorted wave methods, i.e. the ordinary distorted wave method distorted wave method (ODWM) and the indirect-relativistic distorted wave method (IRDWM). Compared to the measured results of superelastic electron scattering from laser excited rubidium at incident energy 20 eV, the result shows that the two kinds of theoretical calculations are partially in agreement with the experimental results. When scattering angle is smaller than 45 degrees, the Stokes parameters and both the calculations of orientation parameter and alignment are consistent with the measured data. Within the scattering angles 70 degrees –120 degrees, the IRDWM results are in agreement with the measurements, which shows that indirect relativistic effects exist during the process of rubidium scattering by low-energy electrons.

Based on the general theory of the electron-photon coincidence experiment, the S tokes parameters of an excited atomic state were calculated with the distorted w ave Born approximation. According to the correlation between experiment and theo ry, the distribution of electron clouds in an excited atomic state can be descri bed by their orientation and alignment parameters. The values obtained are in g reement with the results of the experiments.

The production of spin-polarized electrons and the modulation of polarization direction with liquid crystal variable retarder (LCVR) are discussed. The LCVR ca n play the roles of 1/4, 1/2, 3/4 and whole-wave plates with special voltages in the optical system. And the advantages of using LCVR instead of Pockels cell an d 1/4λ plate are the insensitivity to the incident photon direction, and the va riability of retardation over a large wavelength range without mechanical moveme nt. The polarization direction of spin-polarized electrons can be modulated easi ly by switching the helicity of the circularly polarized light. In order to dete rmine the photon polarization, the spinning polarimeter is developed. And the re sult is also described.

The orientation parameter is used to describe the collision dynamic process and the structure informations of excited atomic state in electron scattering. In density matrix theory, the state multipoles express the structure of atom assembles impacted by particles, and the state multipole of K=1 expresses the orientation vector. In the sysmetry scattering plane system, the orientation vector is denoted by the orientation parameter L⊥, which is calculated from scattering amplititutes, C-G coefficient and 6-j symbol. The orientation parameters of sodium S→P excited by low energy electron are calculated in this paper, and the results are consistent with that obtained from electron-photon coincidence scattering experiment from 2eV—100eV incident energy. The characteristics of orientation angular-distribution vs incident energy are also discussed.

The differential cross-section and parameters of polarization in electron-atom(Na) collision are calculated by the Distorted Wave Method(DWM) in this work.The results are compared with those of experiment and those obtained by Convergent Closed Coupling(CCC) method.It is shown that the DWM is a reliable method with a clear model in moderate to high energy region (5—10 times of threshold energy).

35 autoionising energy levels of Ne atom in ns＇(n = l5-35) and nd＇(n = l3-30) series have been determined experimentally with pulsed electric field optogalvanic spectroscopy. The ionization limit of the ns＇ and nd＇ series was found by parametric fitting and the quantum defects of all these levels were calculated. Instead of the direct discharge, pulsed electric field was used in the experiment, to eliminate Stark effects in the optogalvanic spectroscopy.

Tensor analyzing powers, T20, of outgoing α-particles in the 58Ni( d , α)56Co reaction at detection angles near 0° have been measured for excited states in 56Co for beam energies of 6.75, 7.0, 7.5, 9.0 and 9.5 MeV. Thirty-seven spin-parity combinations for 56Co excited states have been deduced. Previous Jπ ambiguities for 11 of these states have been eliminated, and results in conflict with existing assignments for the levels at 3.235 and 3.378 MeV have been obtained. A search for 0+ states was carried out from angular distribution measurements at forward angles of the unpolarized (d, α) reaction. The combined results from this and previous experiments were found to be in reasonable agreement with calculated level schemes.

The tensor analyzing powers T20 have been measured for 24 states of 40K below 5 MeV following the 42Ca(d↘,α)40K reaction, leading to many new spin‐parity determinations.

This paper discribes the measurements of Rydberg energy levels of Ru in 4d7(4F) ns (n=28-45) and 4d7(4F) nd (n=26-48) series by means of laser resonance excitation-electric field ionization method. The first ionization potential of Ru has been determined by nonlinear fitting program. These energy levels and relevant quantum defects have been calculated by using relativistic self-consistent field method The theoretical results are coincident with the experiments very well. Besides, the first ionization potential drawn from this papes has been compared with the existing data.