We have observed the deflection of Rydberg atoms towards a metallic surface by the van der Waals force. Cs and Na atoms in states of principal quantum number n were sent between two parallel gold-coated mirrors, spaced by a gap w (2.1 μm≤w≤8.5 μm). We measured the value $n_m$ at which the transmission cuts off and from the variation of $n_m$ versus w, we obtained a measure of the atom-surface interaction. For $12<n<30$ this interaction is 3–4 orders of magnitude larger than for ground-state atoms, and it obeys the scaling laws of the Lennard-Jones model.

• Received 28 December 1987

DOI:https://doi.org/10.1103/PhysRevA.37.3594