Nondipole interactions in outer-shell photoionization

New aspects of photoionization are being investigated through measurements and theoretical calculations of nondipole interactions. Interference of electric-dipole amplitudes with electric-quadrupole and magnetic-dipole amplitudes give rise to asymmetries between the intensities of photoelectrons emitted in the forward- and backward-hemispheres with respect to the photon propagation direction. Nondipole asymmetries are sensitive to variations in the magnitudes and phases of photoionization amplitudes such as due to discrete-continuum and continuum-continuum channel coupling. We have developed an electron spectrometer system designed to efficiently measure nondipole asymmetries in photoelectron angular distributions. Using 10-160 eV radiation at Wisconsin's Synchrotron Radiation Center, we are studying nondipole interactions in direct- and resonant-photoionization of the outer shells of atomic rare gases and small molecules. Recent results will be presented.