Probing stray surface electric patch fields using Rydberg atoms

The stray electric “patch” fields present at a Au(1 1 1) surface are investigated by studying the ionization of Rydberg atoms incident at near-grazing angles. Measurements of the threshold conditions required to observe the resulting ions are used to estimate how large such stray fields can be. The data show that the stray fields can be sizeable, as large as ∼103 V cm−1 100 nm from the surface and ∼20 V cm−1 500 nm from the surface, and illustrate the potential of Rydberg atoms for detecting and characterizing surface electric fields.