Surface loss probabilities of H and N radicals on different materials in afterglow plasmas employing H2 and N2 mixture gases

Surface loss probabilities of hydrogen (H) and nitrogen (N) radicals on different wall materials in H2/N2 mixture plasmas have been investigated by employing vacuum ultraviolet (VUV) absorption spectroscopy with a high pressure microdischarge hollow cathode lamp as a light source. The surface loss probability of a radical was calculated by using the lifetime obtained from the decay curve of the radical density in afterglow plasmas. The surface loss probabilities on different walls in the H2/N2 mixture plasmas were higher than those in a pure H2 or N2 plasma. The behaviors of species such as ions and VUV photons as a function of the gas mixture ratio were measured to investigate those influences on plasma-surface interactions. In addition, changes on the surface exposed to the plasma were analyzed by x-ray photoelectron spectroscopy. Quantitative measurements of surface loss probabilities of radicals on various wall materials are expected to be crucially important in achieving good understanding of the int...