Excitation cross section for iridium atoms by slow electrons

The scattering formalism of Arthurs & Dalgarno (1960) is generalized to take account of exchange (but not polarization) in the scattering of slow electrons by molecular hydrogen. The use of a single-centre molecular wavefunction is discussed, and representative calculations of the j = 0→ j = 2 rotational excitation cross-section are carried out in the distorted wave approximation. The inclusion of exchange results in a significant increase (rising from 12% at 0.1 eV to over 70% at 0.5 eV) in the dominant ( p -wave) contribution to the cross-section. It is concluded that exchange effects cannot be ignored in the theoretical discussion of electron energy loss by rotational excitation in swarm experiments.

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A Poor Man’s Approach to Semi-Quantitative Analysis with Electron Energy Loss Spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s143192760000043x ◽

1980 ◽

Vol 38 ◽

pp. 110-111

Author(s):

M. Isaacson

Keyword(s):

Quantitative Analysis ◽

Energy Loss ◽

Electron Energy ◽

Cross Section ◽

Electron Energy Loss Spectroscopy ◽

Excitation Cross Section ◽

Incident Electron ◽

Integral Cross Section ◽

Image Position ◽

Electron Energy Loss

In an earlier paper1 it was found that to a good approximation, the efficiency of collection of electrons that had lost energy due to an inner shell excitation could be written as where σE was the total excitation cross-section and σE(θ, Δ) was the integral cross-section for scattering within an angle θ and with an energy loss up to an energy Δ from the excitation edge, EE. We then obtained: where , with P being the momentum of the incident electron of velocity v. The parameter r was due to the assumption that d2σ/dEdΩ∞E−r for energy loss E. In reference 1 it was assumed that r was a constant.

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The Cross Section for the J = 0 → 2 Rotational Excitation of Hydrogen by Slow Electrons

Australian Journal of Physics ◽

10.1071/ph690715 ◽

1969 ◽

Vol 22 (6) ◽

pp. 715 ◽

Cited By ~ 94

Author(s):

RW Crompton ◽

DK Gibson ◽

AI McIntosh

Keyword(s):

Momentum Transfer ◽

Cross Section ◽

Cross Sections ◽

Vibrational Excitation ◽

The Cross ◽

Excitation Processes ◽

Slow Electrons ◽

And Diffusion ◽

Momentum Transfer Cross Section ◽

Section Analysis

The results of electron drift and diffusion measurements in parahydrogen have been analysed to determine the cross sections for momentum transfer and for rotational and vibrational excitation. The limited number of possible excitation processes in parahydrogen and the wide separation of the thresholds for these processes make it possible to determine uniquely the J = 0 → 2 rotational cross section from threshold to 0.3 eV. In addition, the momentum transfer cross section has been determined for energies less than 2 eV and it is shown that, near threshold, a vibrational cross section compatible with the data must lie within relatively narrow limits. The problems of uniqueness and accuracy inherent in the swarm method of cross section analysis are discussed. The present results are compared with other recent theoretical and experimental determinations; the agreement with the most recent calculations of Henry and Lane is excellent.

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