Electron excitation in atoms and molecules by neutron-nucleus scattering

The quantum theory of electron stimulated desorption developed in two preceding papers is presented in a WKB like form and is applied to the desorption of hydrogen and oxygen from tungsten. Retunnelling processes are taken into account and manifest themselves in an imaginary part in the potential of the desorbing particles. This imaginary part together with a non zero width of the wavepacket leads to quantum effects in the motion of the desorbing particles modifying the corresponding classical results of the reduction factor and of the energy conservation. The modifications turn out to be quite large for hydrogen as well as for oxygen increasing the reduction factor by several orders of magnitude. The isotope effect also is changed appreciable. The parameters of the model are determined from corresponding experimental data such as vibrational levels of the adsorbates, the energy distribution of the desorbing particles and the reduction factor.