Complete experiments in electron–atom impact excitation: present status and future prospects

1996 ◽  
Vol 74 (11-12) ◽  
pp. 929-943
Author(s):  
Nils Andersen ◽  
Klaus Bartschat
Keyword(s):  
Review Paper ◽  
Stokes Parameters ◽  
Impact Excitation ◽  
Future Prospects ◽  
Electron Atom ◽  
Scattering Experiment ◽  
Spin Polarized ◽  
Common Framework ◽  
Theoretical Results ◽  
Present Understanding

An overview is given of the present understanding of excitation in electron–atom collisions, with particular emphasis on the extent to which a "perfect scattering experiment" in the Bederson sense has been achieved. Recent experimental and theoretical results are put into a common framework, generalizing the ideas and systematics, presented in a review paper, of the case of excitation by spin-polarized electron beams. For various levels of complexity, complete sets of coherence parameters are suggested, and their relationships to generalized Stokes parameters and generalized STU parameters are pointed out.

Ionization of heavy inert gases by spin-polarized electrons

1996 ◽  
Vol 74 (11-12) ◽  
pp. 816-821 ◽  
Author(s):  
D. H. Madison ◽  
V. D. Kravtsov ◽  
S. Jones ◽  
R. P. McEachran
Keyword(s):  
Coulomb Interaction ◽  
Spin Asymmetry ◽  
Inert Gases ◽  
Inelastic Electron ◽  
Experimental Measurements ◽  
Polarized Electrons ◽  
Electron Atom ◽  
Atom Scattering ◽  
Spin Polarized ◽  
Theoretical Results

In the collision of a spin-polarized electron with an atom, it is only natural to assume that any observed difference between spin-up and spin-down electrons must originate from spin-dependent forces in the interaction. However, it has been known for sometime that, for inelastic electron-atom scattering, a non-zero spin asymmetry can result from the coulomb interaction ignoring spin-dependent forces on the projectile. In this paper, it is demonstrated that the same type of effect may be expected for ionization of the heavier inert gases. Theoretical results are compared with recent unpublished experimental measurements.

scholarly journals Spin-resolved Alignment and Orientation Effects in Atomic Collisions

1996 ◽  
Vol 49 (2) ◽  
pp. 301 ◽  
Author(s):  
Klaus Bartschat ◽  
Nils Andersen
Keyword(s):  
Density Matrix ◽  
Stokes Parameters ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Matrix Elements ◽  
Atomic Ensembles ◽  
Atomic Collisions ◽  
Orientation Effects ◽  
Scattering Experiment ◽  
Orientation Parameters

The density matrix parametrisation of collisionally excited atomic ensembles is generalised to account for projectile and target spin polarisations. The density matrix elements, containing spin-resolved alignment and orientation parameters, can be determined by measurements of the 'generalised Stokes parameters' introduced by Andersen and Bartschat (1994) to describe scattered-projectile-polarised-photon coincidence experiments. Focusing on electron impact excitation of light alkali-type targets and mercury, the present experimental status of such experiments is reviewed, in particular with regard to the 'perfect scattering experiment' whereby all independent scattering amplitudes are determined.

Fabrication Technologies and Applications of Graphene-based co-polymeric Nano-composites: its challenges and Future works

2019 ◽  
Vol 09 ◽  
Author(s):  
Pratik Chhapia ◽  
Harshad Patel
Keyword(s):  
Review Paper ◽  
Polymeric Coating ◽  
Nano Composites ◽  
Future Prospects ◽  
Electrical And Optical Properties ◽  
In Situ Techniques ◽  
Surface Areas ◽  
Ink Jet ◽  
Enhanced Conductivity

: Graphene based co-polymeric Nano-composites explored and trending in various applications as ascribing to its enhanced conductivity and controlled modification with wide specific surface areas. With the number of advantages of co-polymeric coating on Graphene or Graphene sheets and their derivatives, Graphene based co-polymeric Nano-composites fabricated by various techniques (deposition, ink jet, electro spinning, spin coating, in-situ techniques, etc.) and different conducting co-polymers show its exceptional chemical, mechanical, electrical and optical properties. Therefore, in the today’s world with greater quantities of various properties of co-polymer with Graphene based Nano-composites with enhanced stability, selectivity and sensitivity have been formed. In this review paper, we have particularly focused on recent advancing in fabrication of different technologies with the help of Graphene based co-polymeric Nano-composites and its various trending and future applications. Finally, on the personal standpoint; the key challenges of Graphene based co-polymeric Nano-composites are mentioned in hope to shed a light on their potential future prospects.

Spin-polarization effects in Cherenkov radiation from electrons

2020 ◽  
Vol 98 (7) ◽  
pp. 660-663
Author(s):  
A.A. Peshkov
Keyword(s):  
Spin Polarization ◽  
Cherenkov Radiation ◽  
Stokes Parameters ◽  
Electron Spin Polarization ◽  
Polarized Electrons ◽  
Small Component ◽  
Polarization Effects ◽  
Spin Polarized ◽  
Linearly Polarized ◽  
Spin Polarization Effects

A quantum electrodynamical theory of Cherenkov radiation emitted by spin-polarized electrons moving in an isotropic medium is developed within the density matrix framework. Special attention is paid to the polarization properties of the emitted photons described by means of Stokes parameters. It is demonstrated that, although the Cherenkov radiation is primarily linearly polarized in the plane containing the direction of observation and the path of the electrons, the photons may have a small component of circular polarization of the order of 3 × 10−6 for electron kinetic energy of 500 keV due to the initial electron spin polarization, whose existence can be confirmed by sensitive measurements in the future.

Spin-polarized hydrogen, deuterium, and tritium: I. Ground-state energy calculated by a lowest order constrained-variation method

1989 ◽  
Vol 67 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Magne Haugen ◽  
Erlend Østgaard
Keyword(s):  
Binding Energy ◽  
Molar Volume ◽  
Ground State ◽  
Particle Density ◽  
Variation Method ◽  
Ground State Binding Energy ◽  
Spin Polarized ◽  
Hydrogen Deuterium ◽  
Constrained Variation ◽  
Theoretical Results

The ground-state energy of spin-polarized hydrogen, deuterium, and tritium is calculated by means of a modified variational lowest order constrained-variation method, and the calculations are done for five different two-body potentials. Spin-polarized H↓ is not self-bound according to our theoretical results for the ground-state binding energy. For spin-polarized D↓, however, we obtain theoretical results for the ground-state binding energy per particle from −0.42 K at an equilibrium particle density of 0.25 σ−3 or a molar volume of 121 cm3/mol to + 0.32 K at an equilibrium particle density of 0.21 σ−3 or a molar volume of 142 cm3/mol, where σ = 3.69 Å (1 Å = 10−10 m). It is, therefore, not clear whether spin-polarized deuterium should be self-bound or not. For spin-polarized T↓, we obtain theoretical results for the ground-state binding energy per particle from −4.73 K at an equilibrium particle density of 0.41 σ−3 or a molar volume of 74 cm3/mol to −1.21 K at an equilibrium particle density of 0.28 σ−3 or a molar volume of 109 cm3/mol.

Spin-polarized hydrogen, deuterium, and tritium: II. Pressure and compressibility calculated by a lowest order constrained-variation method

1989 ◽  
Vol 67 (7) ◽  
pp. 649-656 ◽  
Author(s):  
Magne Haugen ◽  
Erlend Østgaard
Keyword(s):  
Molar Volume ◽  
Ground State ◽  
Particle Density ◽  
Variation Method ◽  
Density Region ◽  
Spin Polarized ◽  
Hydrogen Deuterium ◽  
Constrained Variation ◽  
Ground State Energies ◽  
Theoretical Results

The pressure and the compressibility of spin-polarized H↓, D↓, and T↓ are obtained from ground-state energies calculated by means of a modified variational lowest order constrained-variation method. The pressure and the compressibility are calculated or estimated from the dependence of the ground-state energy on density or molar volume, generally in a density region from 0 to 1.5σ−3 corresponding to a molar volume of more than 20 cm3/mol, where σ = 3.69 Å (1Å = 10−10 m); the calculations are done for five different two-body potentials. Theoretical results for the pressure are 54.1–57.9 atm for spin-polarized H↓ 18.4–23.4 atm for spin-plolarized D↓, and 5.6–12.9 atm for spin-polarized T↓ at a particle density of 0.50σ−3 or a molar volume of 60 cm3/mol (1 atm = 101 kPa). Theoretical results for the compressibility are 51 × 10−4 −54 × 10−4 atm−1 for spin-polarized H↓, 108 × 10−4 −120 × 10−4 atm−1 for spin-polarized D↓, and 162 × 10−4 −224 × 10−4 atm−1 for spin-polarized T↓ at a particle density of 0.50σ−3 for a molar volume of 60 cm3/mol. The relative agreement between results for different potentials is somewhat better for higher densities.

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