Photon ? ion angular correlations for He+ + He and He+ + Ne collisions

Abstract

Detailed information about scattering amplitudes of inelastic atomic collision processes is obtained by simultaneous detection of a scattered particle and a photon emitted from a scattered particle. Channels of neighbouring excitation energy, which are difficult to distinguish by optical or energy loss spectroscopy, are demonstrated to be separable making use of a difference in radiative lifetimes and of the resulting different response to an external magnetic field. The results are discussed in the framework of a quasimolecular description of the collision pair. For the He++ He system, a complete picture of the process is obtained by modifying models discussed previously. Qualitative conclusions are drawn for the He + + Ne system.

Coherence effects in low energy Na*(3p)+Na+ scattering: Experiment and semiclassical calculations

“…the electron charge cloud stays space fixed and a n increases due to its projection onto the rotating internuclear axis. This behaviour has been illustrated previously for the case of simple model potentials by Grosser [17]. It should, how- 7.…”

Partial differential cross sections for inelastic He++Ne collisions at low energy

“…The He+(ls) state vector multiplies with + i or -i under reflection when the electronic spin points into the + y or -y direction, respectively. p~ therefore measures the fraction of the He atoms which invert their spin during the collision, from my = -1/2 to + 1/2 or vice versa [13].…”

“…The summation is over the unresolved degrees of freedom, that is, the 1P1 and 3P 1 Ne states and the He + spin polarization. The angular distribution can be used for an experimental determination of most of the density matrix [13,24]. We measured only one such quantity: Psi = (Pll + 01-1).…”

“…For the actual positions of the photon detectors, one has, according to the general theory [13,24], A first criterion for the choice of these positions was to m a k e the a r r a n g e m e n t as sensitive as possible to the m e a s u r e m e n t of P~i-F o r the m e a s u r e m e n t of Psi as (keVdeg) a function of the particle scattering angle, we operate the apparatus with poor energy resolution, in order to avoid a discrimination of the I P 1 o r the 3P 1 channel, and we register the delayed coincidence spectra between the signal from the ion detector and the signals from each of the photon detectors. One observes a peak at the expected delay time and a background, which is essentially independent of the delay time.…”

“…For the channel in (1), which actually summarizes the Ne states 1P o and 3po,l,z, we measured the angular variation of two more quantities: (1) the triplet fraction, and (2), for the states 1P 1 and 3P1, the fraction for which the Ne wave function is aligned at right angles to the scattering plane. The last quantity is of great interest, because it is related to the probability of finding the He ÷ electronic spin inverted after the collision [13].…”