Autoionization widths for Ne sup * (3 s )-Ar and Ne sup ** (3 p )-Ar collisions

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Physical Review, A; (USA)

DOI:https://doi.org/10.1103/PhysRevA.44.167· OSTI ID:5610194

Driessen, J P.J.; Op de Beek, S S; Somers, L M.T.; Beijerinck, H C.W.; Verhaar, B J ^[1]

---

1. Physics Department, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands (NL)

Following Jones and Dahler (Phys. Rev. A 37, 2916 (1988)) we study the theory of the process of ionization within the framework of the Feshbach projection-operator formalism, with the discrete fine-structure states (before ionization) and the continuum states (after ionization) as the two separate subspaces of Hilbert space. For the Ne{sup *}(3{ital s})-Ar and Ne{sup **}(3{ital p})-Ar systems we have calculated {ital ab} {ital initio} autoionization widths. In the approximation in which only two electrons play an active role, the coupling matrix element between the two subspaces is a linear combination of two-center two-electron integrals for the exchange and the radiative mechanisms. In general, our calculations support the semiempirical results of Morgner (J. Phys. B 18, 251 (1985)) for the coupling matrix elements as derived from experimental data. The autoionization widths {Gamma}{sub {ital J}{prime},}{ital J{Omega}} are presented for initial states {vert bar}{ital J},{Omega}{r angle} of the Ne{sup *(*)} atom and final states {vert bar}{ital J}{prime}{r angle} of the Ar{sup +} ion. They show a pronounced {Omega} dependence and a strong correlation of initial and final states, e.g., {vert bar}0,0{r angle}{r arrow}{vert bar}3/2{r angle} and {vert bar}2,2{r angle}{r arrow}{vert bar}3/2{r angle}. For the Ne{sup *}(3{ital s}) states the two-center two-electron calculation is in good agreement with the two-state basis of Driessen {ital et} {ital al}. (Phys. Rev. A 42, 4058 (1990)), based on a one-electron overlap approximation. In a semiclassical model the polarized-atom ionization cross sections are calculated. For the Ne{sup **}(3{ital p})-Ar system the energy dependence of both the polarization effect and the average cross-section value is reproduced very well, in contrast to the one-electron approximation.

• OSTI ID: 5610194
• Journal Information: Physical Review, A; (USA), Journal Name: Physical Review, A; (USA) Vol. 44:1; ISSN 1050-2947; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
AUTOIONIZATION
COLLISIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
GASES
IONIZATION
LEVEL WIDTHS
MANY-BODY PROBLEM
MATHEMATICAL OPERATORS
NEON
NONMETALS
PENNING EFFECT
PROJECTION OPERATORS
RARE GASES
TWO-BODY PROBLEM