The sticking coefficient of hydrogen atoms on a metal: Exact results for a model Hamiltonian

Previously computed values of the sticking coefficient of H atoms on a model solid with energy loss to electron-hole pairs, are converted to exact (unitary) values for a model Hamiltonian which allows sticking, and elastic scattering only. This is done without further computation because, for the physical process treated, namely the “gettering” of a gas in a closed vessel, the decay of the initial state is given essentially exactly by the quasi-particle approximation used in the original computations. The only (trivial) calculation needed, stems from the necessity to define carefully the sticking coefficient in terms of the decay rate, and the collision number. We also comment briefly on certain aspects of the application of text-book scattering theory, to the gettering process.