Effect of atomic polarization on two-photon electron detachment from the corresponding negative ions

Michael Scheer, R. C. Bilodeau, Harold K. Haugen

Henrik Stapelfeldt, J O Gaardsted, T. Andersen +1 more

Павел Абрамович Головинский, B. A. Zon

Clifford Trainham

Christophe Blondel, F. Dulieu, Christian Delsart

Multiphoton excitation with elliptically polarized light brings out more information in the photodetachment or photoionization processes than linearly polarized light. This information can be reached by recording photoelectron angular distributions for several values of the ellipticity angle, and fitting the whole set of data with an analytic formula. We give here the appropriate formula, valid for any number N of exciting photons, with the assumptions of (1) an initially even and momentumless (J equals 0) atom or ion and (2) that after excitation of an electron, the residual core be left in an odd state. These are the conditions met by multiphoton detachment from halogen negative ions. With elliptically polarized light of (lambda) equals 1064.2 nm, we have measured the angular distributions of three-photon detached electrons from the ion I-, and four-photon detached electrons from Cl- and F-. The experimental results are quantitatively analyzed and commented on.

Wilhelm Becker, Li-E Li, John K. McIver

Two-colour photodetachment of a negative ion modelled by a three-dimensional delta-function potential is theoretically investigated. The high-frequency low-intensity field is closely tuned to the detachment energy of the ion, the low-frequency high intensity field creates a ponderomotive potential of 2.6% of the detachment energy and at the same time sidebands. The two fields are circularly polarized with either equal or opposite polarizations. In accordance with the Wigner threshold law, for equal and opposite polarizations, the sideband-induced thresholds are above or below the one-photon detachment threshold, respectively. The one-photon threshold is markedly visible for opposite polarizations at the position shifted by the full ponderomotive potential. For equal polarizations and low frequencies it is not noticeable at all.