Large Nondipole Effects In The Angular Distributions Of K-Shell Photoelectrons From Molecular Nitrogen

Measurements of angular distributions of K-shell electrons photoejected from molecular nitrogen are reported which reveal large deviations at relatively low photon energies ((h) over bar omega less than or equal to 500 eV) from emission patterns anticipated from the dipole approximation to interactions between radiation and matter. A concomitant theoretical analysis incorporating the effects of electromagnetic retardation attributes the observed large nondipole behaviors in N-2 to bond-length-dependent terms in the E1 x (E2, M1) photoelectron emission amplitudes which are indicative of a potentially universal nondipole behavior in molecular photoionization.