Selective reflection from Rb layer with thickness below $\lambda$/12 and applications

We have studied the peculiarities of selective reflection from Rb vapor cell with thickness $L<$ 70 nm, which is over an order of magnitude smaller than the resonant wavelength for Rb atomic D${}_1$ line $\lambda$ = 795 nm. A huge ($\approx$ 240 MHz) red shift and spectral broadening of reflection signal is recorded for $L=$ 40 nm caused by the atom-surface interaction. Also completely frequency resolved hyperfine Paschen-Back splitting of atomic transitions to four components for ${}^{87}$Rb and six components for ${}^{85}$Rb is recorded in strong magnetic field ($B>$ 2 kG).