Open Access. Powered by Scholars. Published by Universities.®
Atomic, Molecular and Optical Physics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Atomic, Molecular and Optical Physics
Formation Of Positronium In E+ + H- Collisions, Jack C. Straton, Richard J. Drachman
Formation Of Positronium In E+ + H- Collisions, Jack C. Straton, Richard J. Drachman
Physics Faculty Publications and Presentations
Cross sections for positronium formation by capture from the negative hydrogen ion are given. Orthogonalization corrections to the Coulomb (first-order) Born approximation (CBA) differential and total cross sections are calculated using approximate H- wave functions of both Löwdin [Phys. Rev. 90, 123 (1953)] and Chandrasekhar [Astrophys. J. 100, 176 (1944)]. The present calculation of the CBA cross sections using the post interaction for Löwdin’s wave function (LCBAPS) disagrees with the calculation of Choudhury, Mukherjee, and Sural (CMS) [Phys. Rev. A 33, 2358 (1986)], whereas our results using the prior interaction agree. Thus, where CMS found an order …
Fock-Tani Hamiltonian For Reactions Involving Two-Electron Atoms, Jack C. Straton
Fock-Tani Hamiltonian For Reactions Involving Two-Electron Atoms, Jack C. Straton
Physics Faculty Publications and Presentations
The Fock-Tani Hamiltonian is found for scattering processes involving up to two ions and two electrons. Possible bound-state species include one or two electrons bound on an ion fixed at the origin, and a one-electron projectile atom. A diagrammatic technique is illustrated that simplifies the algebra of the transformation. Coulomb- or plane-wave states are automatically generated by the same asymptotic Hamiltonian for all arrangement channels.
Double Excitation Of Helium By Fast Particles Of Charge Z, James H. Mcguire, Jack C. Straton
Double Excitation Of Helium By Fast Particles Of Charge Z, James H. Mcguire, Jack C. Straton
Physics Faculty Publications and Presentations
Results of calculations of double excitation of helium to n=2 states for fast projectiles of charge Z are presented. Nonzero Z3 contributions for single and double excitation occur only when time-ordering contributions from the second-order amplitude are nonzero. For double excitation, electron correlation must also be nonzero to obtain Z3 terms. The time-ordering effects arise from virtual off-energy-shell intermediate states. As with second-order amplitudes for Thomas singularities in electron capture, the energy-nonconserving amplitude is connected to the second-order energy-conserving amplitude by a dispersion relation. Comparison is made with experiment.
First-Order Amplitude For General State-To-State Transitions In Hydrogen By Projectile Impact, Jack C. Straton
First-Order Amplitude For General State-To-State Transitions In Hydrogen By Projectile Impact, Jack C. Straton
Physics Faculty Publications and Presentations
The closed analytic form for bound-state transitions due to projectile impact is found in the intermediate representation. The coordinate integral is obtained by evaluating the remaining two integrals in the general multicenter integral derived previously [J.C. Straton, Phys. Rev. A 41, 71 (1990)]. Evaluating the remaining time integral depends upon relating a sum of modified Bessel functions of the second kind KN+1/2(z) to a simple polynomial in 1/z. The results of Van Den Bos and De Heer [Physica 34, 333 (1967)] are shown to be missing a phase factor of (-i)(l′+l)