Laser-stimulated photodetachment of electrons from the negatively charged dielectric substrates

The photon-stimulated emission of bulk electrons has been extensively studied for various types of materials, while the photodetachment of surplus surface electrons has not been fully explored. The photodetachment barrier energy is commonly defined by the surface electron affinity of material, which is typically less than the work function and more pronounced for non-conducting substrates and in environments with a continuous flux of electrons to the surface, such as in gas discharge plasmas. Herein, it is experimentally shown that the photodetachment yield of surplus electrons created by plasma-induced charging of non-conductive surfaces of dielectric materials depends on the initial surface charge density and do not correlate with the tabulated affinity values of these materials under gas discharge charging conditions. This result obtained using laser-stimulated photodetachment for fused silica, boron nitride, and alumina, is critically important for the understanding of charging and discharging dynamics, secondary electron emission, and photo emission effects affecting plasma–wall interactions relevant to surface and capacitively coupled discharges, dusty plasmas, electrostatic probe diagnostics, and applications for plasma processing of materials, plasma propulsion, and gas breakdown.