title: Control of near-threshold detachment cross sections via laser polarization.
abstract: The behavior of near-threshold cross sections for dissociation of a target into a pair of particles, as described by Wigner's threshold law, can depend sensitively on the angular momentum of the particles. In this Letter, we investigate the near-threshold nonresonant two-photon detachment process in the negative ion of gold. The expected s-wave threshold behavior is observed with linearly polarized light. Closure of the s-wave channel is realized by using circular polarization, allowing the first observation of a d-wave threshold. Practical applications are discussed, including extensions which could prove valuable for investigations of negative ions with near-threshold structure.
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1.
authors.forename: R C
authors.initials: RC
authors.lastname: Bilodeau
authors.forename: M
authors.initials: M
authors.lastname: Scheer
authors.forename: H K
authors.initials: HK
authors.lastname: Haugen