Quantum Effects in the Sticking of Ne on a Flat Metal Surface

The sticking coefficient of thermal neon atoms on a flat Ru(001) surface ($T_s=7\mathrm{}$ K) is found experimentally to be very low and strongly dependent on gas temperature (1×${10}^{-3\mathrm{}}$ to 8×${10}^{-2\mathrm{}}$ for $T_g$ from 600 to 30 K) on the clean surface, and to increase strongly with coverage to about 0.7. The zero-coverage values are incompatible with classical mechanical theory, irrespective of assumed interaction parameters, requiring substantial zero-phonon scattering. Calculations treating the energy transfer to phonons quantum-mechanically can reproduce the data with reasonable parameters.