Two-Photon Spectroscopy On Rubidium Vapor Contained In Porous Glass

We studied spectroscopicaly the fluorescence of a long-lived state of Rubidium for the atomic vapor confined to the micrometric interstices of porous glass cells. The system is studied with the aim of investigating the spectroscopic consequences of the confinement of atoms. The exited level is reached through atom-photon transition. Radiation fields interacting with the atoms in the pores of glass are diffuse due to the propagation in this highly scattering medium. The fluorescence spectra obtained have unusual lineshapes that are well described with a simple theoretical model, considering the diffuse characteristic of the light field. The fluorescence spectra lineshape measured do not exhibit effects due to the three dimensional confinement, however, this effect is noticeable when the fluorescence decay time curves are observed. They show a reduction in its decay time compared with the signal in a cell without confinement.