Detection of hydrogen adsorbed on tungsten surfaces using the 1H(15N, αγ)12C reaction

An ultratugh vacuum (UHV) system for the 1H(15N, αγ)12C reaction analysis of hydrogen adsorbed on well-defined surfaces was constructed. The detection limit of hydrogen coverage on the W(001) surface was 4 × 1013 H atoms/cm2 (150 of the full monolayer coverage). The ion-stimulated desorption process for hydrogen atoms due to the 15N ion beam was studied by measuring the decay of hydrogen coverage on W(001) at low background gas pressures, and the desorption cross section was obtained as 2.4 × 10−16 cm2. Hydrogen coverage on the W(110) surface compared with that on W(001) was estimated from the intensity profiles given by measurement of the resonance energy width.