Two-photon laser-induced fluorescence measurements of transition frequencies and lifetimes of laser-excited Na atoms are presented as a function of distance (2–3nm) to metal surfaces of different roughness. We characterized the surface roughness by fitting a Gaussian height–height correlation function to force microscopic data. An unusually small red shift of the Na transition frequency of a few hundred megahertz was observed. In the framework of a quantum-mechanical linear optical response formalism we fitted the lifetime and the frequency shift data simultaneously to obtain effective parameters of a selvedge dielectric function. In that way we are able to take into account both surface roughness and nonlocality, which in turn result in the observed small frequency shifts.
© 1997 Optical Society of America
[of America ]
F. Balzer, V. G. Bordo, and *H.-G. Rubahn, "Frequency shifts and lifetime changes of sodium atoms near rough metal surfaces," Opt. Lett. 22, 1262-1264 (1997)