The sticking of H2(ν=1, J=1) on Cu(100) measured using laser-induced thermal desorption

The sticking of vibrationally excited H-2 on Cu(100) is measured using molecular beam techniques and stimulated Raman scattering for state preparation. Laser Induced Thermal Desorption (LITD) is developed to measure surface hydrogen coverage by calibration with known H-coverages. We find that LITD can be effectively used to measure adsorbed hydrogen concentrations with a sensitivity of better that 1% of a monolayer. Sticking coefficients of H-2 are determined from the ratio coverage to exposure. Measurements are made for H-2 incident translational energies in the range of 74-189 meV. For the first excited vibrational state, we find and an upper limit of the H-2 sticking coefficient to be 0.065 at E-i = 74 meV and 0.17 at E-i = 189 meV. These limits imply that previous measurements of loss of H-2(nu = 1) upon scattering from Cu(100) cannot be predominately a result of dissociative adsorption. The results are broadly consistent with results determined from quantum-state resolved measurements for recombinatative desorption and the principle of detailed balance for H-2 from Cu(111).