Abstract
A many-body formalism utilizing a tunneling operator is proposed for the photoemission process, thereby avoiding the artificial separation of the process into distinct steps. The lowest-order term in the formalism, corresponding to surface scattering, is developed in detail for simple metals. Energy-distribution curves from this "surface term" are presented for both free and interacting electrons. Many-body effects, including plasmarons, are prominent in the latter and have tentative experimental support.