  We study the interaction of particles with a domain wall at a
symmetry-breaking phase transition by perturbing about the domain wall
solution. We find the particulate excitations appropriate near the domain wall
and relate them to the particles present far from the wall in the uniform
broken and unbroken phases. For a quartic Higgs potential we find analytic
solutions to the equations of motion and derive reflection and transmission
coefficients. We discover several bound states for particles near the wall.
Finally, we apply our results to the electroweak phase transition in the
standard model.
