Rearrangement collisions in highly excited states of atomic hydrogen

Journal Article · Thu Feb 01 04:00:00 EST 1979 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.19.655· OSTI ID:6324129

Sil, N C; Saha, B C; Saha, H P; Mandal, P

A new straightforward method for the evaluation of the rearrangement-scattering amplitude has been proposed to study the following reactions: H/sup +/ + H(1s) ..-->.. H(nlm) + H/sup +/; e/sup +/ + H(1s) ..-->.. (e/sup +/e/sup -/) (nlm) + H/sup +/, 2 < or = n < or = infinity and l = 0,1, in the first Born approximation embodying the full interacting potential. A contour-integral representation has been used for the Laguerre polynomial that occurs in the final-state wave function. The amplitude containing only the electron-nucleus interaction has been evaluated analytically. But the amplitude for the projectile nucleus interaction involves a contour integration on a circular path, and this integral can easily be evaluated numerically. To provide an estimate of the asymptotic cross section, expressions for the transition amplitudes when n ..-->.. infinity have also been given. It is shown explicitly that the charge-exchange cross sections asymptotically obey the inverse n-cube law irrespective of the incident energy. In proton-hydrogen collisions our computed results for the low-lying discrete states show excellent agreement with the earlier theoretical values of Mapleton and those of Band as well. For positronium (Ps) formation all the reported results, except for the 2s excitation, are quite new. Zeros of the angular distributions are seen to be almost independent of the principal quantum number n, but dependent only on the projectile energy. n/sup 3/sigma shows regular smooth behavior with increasing n, and the results for n = 18 and n ..-->.. infinity agree within 0.5% throughout the energy range considered.

• Research Organization: Department of Theoretical Physics, Indian Association for the Cultivation of Science, Calcutta-700 032, India
• OSTI ID: 6324129
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 19:2; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AMPLITUDES
ATOM COLLISIONS
ATOMIC IONS
BORN APPROXIMATION
CATIONS
CHARGE EXCHANGE
CHARGED PARTICLES
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
HYDROGEN
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
ION COLLISIONS
ION-ATOM COLLISIONS
IONS
NONMETALS
POSITRON COLLISIONS
POSITRON-ATOM COLLISIONS
POSITRONIUM
SCATTERING AMPLITUDES