Adsorption and desorption of hydrogen on bare and Xe-covered Cu(111)

Using polarization-modulated ellipsometry to monitor adsorbate coverage in-situ we studied the activated adsorption of filament-heated molecular hydrogen on Cu(111) and subsequent isothermal desorption of hydrogen adatoms. The adsorption is characterized by a zeroth-order kinetic with a constant sticking probability of S₀=0.0062 up to θ=0.25 followed by a Langmuir kinetic until the saturation coverage θ_s=0.5 is reached. The desorption follows a second-order kinetic with an activation energy of 0.63 eV and a pre-exponential factor of 1×10⁹ /s. A pre-adsorbed monolayer of Xe atoms on Cu(111) with a desorption activation energy of 0.25 eV and a pre-exponential factor of 8×10¹⁴ /s efficiently blocks the subsequent adsorption of hot molecular hydrogen making physisorbedXe useful as templates for spatial patterning of hydrogen adatom density on Cu(111).