Polar and azimuthal dependence of the molecular frame photoelectron angular distributions of spatially oriented linear molecules

The general form of the molecular frame photoelectron angular distributions (MFPADs) for linear ground-state molecules ionized by linearly polarized light ((n) over cap) is reported. A comparison between computed and measured MFPADs as a function of the polar and azimuthal emission angles is presented for photoionization of NO leading to the c (3)Pi state of NO+. The importance of the azimuthal dependence of the MFPADs for the determination of the symmetry of the states involved in the excitation and of the underlying photoionization dipole matrix elements is demonstrated.