Theoretical Concepts and Methods for Electron Emission from Solid Surfaces

Kinetic electron emission due to perpendicular impact of carbon ions on tungsten surfaces

“…[11][12][13][14]). In one case, it is a direct particle-free-electron collision, which has also a simple classical analogue, and the other one is a promotion model, which in metallic samples is a purely quantum-mechanical process.…”

Interaction potentials for fast atoms in front of Al surfaces probed by rainbow scattering

“…The disparate energy and velocity scales for parallel and perpendicular motions have also a decisive impact on the validity and applicability of various approximations to atom-surface potentials. While the perpendicular energy E Ќ controls the distance of closest approach and thus the isopotential lines to be probed, the parallel energy E ʈ , or more precisely, the velocity component parallel to the surface v ʈ determines whether quasistatic interaction potentials 11 apply or the dynamical response has to be accounted for. For small v ʈ Ӷ v e ͑v e : characteristic speed of the electronic motion such as the Fermi velocity v F for metals or orbital velocity v orb of the valence electrons in atoms͒ quasistatic ͑or zero-frequency͒ potentials V͑r ជ͒ = V͑ =0,r ជ͒ are expected to be valid while at larger velocities nonadiabatic effects will set in.…”

“…Scattering from the surface proceeds in the regime of "surface channeling" by averaged interaction potentials. 7,11 The axial channeling or string potential is given by…”

“…For binary atom-atom collisions their applicability is limited to intermediate collision velocities ͑v p Շ v e ͒ where neither strongly inelastic processes ͑such as ionization at higher ve-locities͒ nor formation of a quasimolecular complex at lower velocities are of importance. 6,11 This class of potentials is readily available for all pairs of projectile and surface atoms and will serve as point of reference for more advanced potentials.…”

Spin-dependent low-energy electron transport in metals

“…Two points are worth mentioning. As the stochastic forces and their un-derlying collision kernels are derivable from ͑mostly͒ quantum ͑linear͒ response functions, the resulting transport theory corresponds to a hybrid classical-quantum treatment 16 despite its purely classical appearance. In fact, in the limit V͑r ជ i ͒ = 0, the treatment is equivalent to a quantum-kinetic ͑Boltzmann͒ equation since classical-quantum correspondence holds for impulsively perturbed free-particle propagation in line with Ehrenfest's theorem.…”