Resonant quenching of gas-phase Cs atoms induced by surface polaritons

Near-field coupling between an excited atom and a surface-polariton mode can dramatically modify atomic branching ratios, because of surface-induced enhancement of a resonant decay channel. We show here that Cs(6D(3/2)) transfer towards Cs(7P(1/2)) (at lambda = 12.15 microm), negligible in free space, becomes efficient in the vicinity (< or =100 nm) of a sapphire window, due to a 12 microm resonance in the surface-polariton modes. The experiment relies on a selective reflection probing on the 7P(1/2)-10D(3/2) transition.