Controlled strong non-dipole effects in photoionization of confined atoms

It is demonstrated that non-dipole effects in low energy photoionization of atoms surrounded by a repulsive semi-transparent potential can be increased by many orders of magnitude due to virtual levels occurring in the spectra of photoelectrons as a result of confinement. The strengths, widths and positions of such resonances in non-dipole channels can be controlled by altering the characteristics of the confining potential, and under certain circumstances can be so large that treating quadrupole transitions as a perturbation breaks down, even for photon energies as low as tens of eV. Our conclusions have relevance to the interpretation of non-dipole photoemission spectra from solids, molecules, atoms trapped inside fullerene molecules, quantum dots, etc. (author). Letter-to-the-editor