Measurement of coherence parameters for the electron impact excitation of the 31D state of helium at small electron scattering angles
- 28 December 1988
- journal article
- Published by IOP Publishing in Journal of Physics B: Atomic, Molecular and Optical Physics
- Vol. 21 (24) , L741-L745
- https://doi.org/10.1088/0953-4075/21/24/006
Abstract
The authors have measured the Stokes parameters of the coincident decay radiation resulting from the electron impact excitation of the 31D states of helium. This was done as a function of the electron scattering angle theta e in the small scattering angle range (15'-30') at energies of 45 and 60 eV. The results do not provide a preference for any of the theoretical models currently available. Measurements of the Stokes parameter P3 (proportional to Lperpendicular to ) tend to confirm the predictions of the distorted-wave Born approximation (DWBA). For the coherence parameters Pl and gamma resulting from the measurements of P1 and P2, the results for Pl seem to be consistent with the dipole multichannel eikonal treatment (DMET) and with the first-order many-body theory (FOMBT), whereas the results for gamma are in disagreement with these theories.Keywords
This publication has 12 references indexed in Scilit:
- Collisional alignment and orientation of atomic outer shells I. Direct excitation by electron and atom impactPhysics Reports, 1988
- A polarisation-correlation analysis of the 31D state of helium excited by electron impactJournal of Physics B: Atomic and Molecular Physics, 1987
- A coincidence study on the electron impact excitation of the 33P state of heliumJournal of Physics B: Atomic and Molecular Physics, 1987
- Calculation of the electron impact coherence parameters for excitation of the 31D state of heliumJournal of Physics B: Atomic and Molecular Physics, 1987
- Orientation and alignment parameters for e-He (11S to 31D) collisionsJournal of Physics B: Atomic and Molecular Physics, 1987
- Measurements of complex scattering amplitudes for electron impact excitation of the 31D and 31P states of heliumJournal of Physics B: Atomic and Molecular Physics, 1983
- Coherence study of S→D excitation: Li(2s→3d) excitation of Li-He collisionsJournal of Physics B: Atomic and Molecular Physics, 1983
- A scattered-electron cascaded-photon coincidence experiment on the electron impact excitation, of the 31D state of heliumJournal of Physics B: Atomic and Molecular Physics, 1981
- Orientation by collisionJournal of Physics B: Atomic and Molecular Physics, 1981
- Photon Vector Polarization and Coherence Parameters in an Electron-Photon Coincidence Experiment on HeliumPhysical Review Letters, 1976