Study of the Interaction of Rubidium Atoms with Sapphire Surface Using Spectroscopic Nanocells

The influence of a dielectric surface on Rb atoms ( D 2 -line) at nanometer distances has been experimentally studied. Use of a nanocell with a wedge-shaped gap filled with atomic rubidium made it possible to study the influence of atoms at distances in the range 45–150 nm from the surface of a commercial sapphire window. The 85 Rb and 87 Rb atomic transitions were strongly broadened at distances <130 nm from the sapphire surface due to Van-der- Waals interactions. Their frequencies shifted to the low-frequency spectral region. Use of the second-derivative method of nanocell absorption spectra made it possible to measure the Van-der-Waals interaction coefficient C 3 = 1.8 ± 0.3 kHz·μm 3 for the Rb D 2 -line. An additional red shift was shown to occur at a nanocell thickness of 65 ± 5 nm due to dipole–dipole interaction of Rb atoms as the atomic density increased. The results could be used to develop miniature submicron devices.