Direct determination of partial wave contributions in the σ* shape resonance of CO molecules

The first complete experiment for the C K-shell of CO molecules in the region of the sigma* shape resonance has been performed by detecting photoelectrons in coincidence with fragment ions. Four ratios of dipole matrix elements and four phase shift differences have been extracted from the experi mental data. Their analyses show that, in the sigma* shape resonance due to the l mixing, d and f partial waves give the main contribution to the cross section, and f and g waves give the main contribution to a rapid increase of phase shift by pi.