Electron-photon interaction near the surface of a planar target

A photon in a momentum eigenstate, incident on an inhomogeneous screen, produces the superposition of an infinite number of evanescent states (ES) near the screen's surface. Accordingly, the two different types of ES (or evanescent waves) named as EW1 and EW2 are described in 2 respective experimental setups: 1) total internal reflection and 2) scattering on an inhomogeneous planar target. Some interactions are considered between an EW2-photon and the environment. The latter may include a beam of probing particles and/or the screen on which the EW2 are formed. Some new properties of ES are described, such as complex energy eigenvalues in case of a movable screen, and evanescence exchange between the interacting objects. This reveals the connection between ES and the Gamow states of the studied system. The energy-momentum exchange between EW2 and the probe (e.g., an electron) is highly selective and may collapse the superposition of photon EW2- eigenstates to a single EW-eigenstate of the probing particle. Possible imprints of EW2 in the far field are briefly discussed and a simple experiment is suggested for their observation.