Abstract
Surface-induced transitions between Zeeman sub-levels of metastable neon atoms traversing a micro-slit copper grating are investigated. The quadrupolar part of the surface van der Waals interaction suddenly perturbs the evolution of the Zeeman sub-levels in a magnetic field B, giving rise to van der Waals - Zeeman transitions. Exothermal inelastic transitions are identified by the related deflection γ. In a diagram (γ, B1/2) the location of the inelastic peaks is fitted by straight lines of slopes proportional to |Δm|−1/2, where Δm is the magnetic number change.