High-resolution angle-resolved measurements in atoms and molecules using advanced photoelectron spectroscopy at the ALS

A two-dimensional photoelectron imaging technique using time-of-flight spec trometry and a high-resolution SES-200 electron energy analyzer have been u sed with photons from the atomic and molecular undulator beamline of the Ad vanced Light Source to study the structure and dynamics of atoms and molecu les. The analyzers are rotatable around the direction of the photon beam, a llowing angular-dependent studies to be performed. Results on the photoexci tation and decay mechanisms of doubly excited resonances in neon illustrate the importance of spin-orbit effects for such a light atom, since signific ant breakdown of LS-coupling was measured for such a light atom. Also, full y vibrationally resolved Auger electron spectra measured under Resonant Ram an conditions following the C 1s --> pi* excitation in a diatomic molecule, CO, is presented which allows us to probe the core excited states, their e xcitation and de-excitation dynamics with unprecedented resolution. (C) 199 9 Elsevier Science B.V. All rights reserved.