Anionic photofragmentation of CO: a selective probe of core-level resonances.

Anion-yield spectroscopy using x rays is shown to be a selective probe of molecular core-level processes, providing unique experimental verification of shape resonances. For CO, partial anion and cation yields are presented for photon energies near the C K edge. The O- yield exhibits features above threshold related only to doubly excited states, in contrast to cation yields which also exhibit pronounced structure due to the well-known sigma* shape resonance.

Application of a dc Fano effect polarized electron source to low-energy electron-atom scattering.

A polarized electron source based upon the photoionization of unpolarized Cs atoms by circularly polarized light (Fano effect) has been developed and applied to the study of spin dependence in low-energy electron-atom scattering. Electron intensities of 10 nA with polarizations of 0.63+/-0.