Quantification of Gas-Phase H-Atom Number Density by Tungsten Phosphate Glass

Abstract

It is shown that H-atom densities in the gas phase can be evaluated by simply measuring the change in optical transmittance of tungsten phosphate glass plates. Tungsten oxide (WO3) doped in phosphate glass plates can be reduced by exposure to H atoms and the degree of reduction can be evaluated from the change in their optical transmittance. The difference in the logarithms of the transmittances before and after the reduction showed a linear dependence on the H-atom density evaluated by a vacuum-ultraviolet laser absorption technique. No change in the transmittance was observed in the absence of H atoms, showing that reduction of WO3 by H2 molecules can be ignored.