Theory of Smith-Purcell radiation from a 2D array of small noninteracting particles

We construct the first-principles theory for the scattering of the Coulomb field of a fast electron traveling along an array of nano- or microparticles. The electron’s trajectory is arbitrarily oriented in the plane parallel to the surface. We show that Smith-Purcell radiation accompanying this process results in very rich diffraction patterns, which differ dramatically from the ones for conventional diffraction gratings; a numerical analysis was made for THz frequencie