Quasi-elastic scattering of electrons at large momentum transfer

Precision measurements of the energy of keV electrons scattered ‘elastically’ over large angles from solid films or gas-phase molecules show that these electrons have lost some energy. In particular scattering from a system that contains hydrogen and carbon reveals two well-separated elastic peaks. The amount of energy lost in the deflection of the electron depends not only on the mass of the nucleus the electron scattered from, but also on the momentum of this nucleus. We make an estimate of the cross section for these elastic scattering processes. These cross sections do not reproduce the observed intensities very well, in particular the observed hydrogen intensity is for the solid film experiment smaller than expected. With increasing energy loss the time-scale of the collision process decreases. The decrease of the hydrogen cross section is possibly due to quantum correlation effects of the proton at the short timescale of the collision.