DEMONSTRATION OF STRONG FORWARD-BACKWARD ASYMMETRY IN THE C1S PHOTOELECTRON ANGULAR-DISTRIBUTION FROM ORIENTED CO MOLECULES

Angular distributions of C(ls) photoelectrons emitted from oriented CO molecules were measured using a new method: mass and angle-resolved p hotoelectron-photoion coincidence spectroscopy. Along with the angular momentum composition of the photoelectron wave, the experiment reveal s pronounced forward-backward asymmetries in the photoemission intensi ty with respect to the molecular orientation. This asymmetry, being ob served for the first time in molecular photoionization, is interpreted in terms of multiple scattering effects. Calculations using the MS-Xa method show good quantitative agreement with the presented experiment al results.