title: Excitation of electronic states of Ar, H(2), and N(2) by positron impact.
abstract: We have measured the first state-resolved, absolute cross sections for positron excitation of electronic states of an atom or molecule using a high resolution (Delta E approximately 25 meV FWHM) beam of positrons from a Penning-Malmberg trap. We present cross sections for the excitation of the low-lying levels of Ar, H(2), and N(2) for incident positron energies between threshold and 30 eV. For Ar and H2, comparison can be made with theoretical calculations, and, in the case of H(2), the results resolve a significant discrepancy between the only two available calculations.
authors.affiliation: Department of Physics, University of California, San Diego, California 92093-0319, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Sullivan
authors.forename: J P
authors.initials: JP
authors.lastname: Marler
authors.forename: S J
authors.initials: SJ
authors.lastname: Gilbert
authors.forename: S J
authors.initials: SJ
authors.lastname: Buckman
authors.forename: C M
authors.initials: CM
authors.lastname: Surko