Angular distributions of vibrationally-resolved C 1s photoelectrons from fixed-in-space CO molecules: vibrational effect in the shape-resonant C 1s photoionization of CO

Abstract

We have measured vibrationally-resolved molecular-frame photoelectron angular distributions (MF-PAD) from the C 1s level of CO molecules in the σ shape resonance region. The MF-PAD’s for vibrational levels ( v f =0, 1, and 2) in the C 1s→ εℓσ channel are apparently different one from another at each incident photon energy. These experimental MF-PAD’s agree with the present theoretical results from averaging the nuclear distance dependent dipole matrix elements with the relaxed core Hartree–Fock calculations. The results show that the MF-PAD’s sensitively depend on the vibrational levels. This means that the internuclear distance dependences of phases and of magnitudes of dipole matrix elements play a crucial role in the C 1s photoionization of CO.