  We present experimental observations of atom-light interactions within tens
of nanometers (down to 11~nm) of a sapphire surface. Using photon counting we
detect the fluorescence from of order one thousand Rb or Cs atoms, confined in
a vapor with thickness much less than the optical excitation wavelength. The
asymmetry in the spectral lineshape provides a direct read-out of the
atom-surface potential. A numerical fit indicates a power-law
$-C_{\alpha}/r^{\alpha}$ with $\alpha=3.02\pm0.06$ confirming that the van der
Waals interaction dominates over other effects. The extreme sensitivity of our
photon-counting technique may allow the search for atom-surface bound states.
