Dynamics of Optical Pumping Processes in Coated Cells Filled with Rb Vapour

A better theoretical understanding of the atom - surface interactions and of the experimental consequences and applications to a reproducible method for the construction of reliable coated absorption cells is the main scope of our research. In this paper we report on the influence of diode laser intensity and of diode frequency scanning rate on the spectrum of the D-2 line of Rb atoms, contained in paraffin or PolyDiMethylSiloxane (PDMS) coated glass cells. The anti-relaxation coating of inner walls of the glass cells allows to extend the optical orientation of atoms induced by the light to the entire cell volume and atomic velocity distribution. Moreover, in order to further investigate the role of atoms adsorbed in the anti-relaxation coatings, the D-2 line spectra are compared for two cases: without and with illumination of the walls of the cell by an ultraviolet lamp. A theoretical model based on rate equations is introduced in order to analyze the experimental results. The extracted behaviour is a simple method to test the conditions of a coated surface. This finds applications in all cases where timely assessment of an organic coating layer is critical, from vapour spectroscopy to magneto-optical trapping of rare and radioactive species.