Threshold energy for the photon-stimulated desorption of Rb atoms from polydimethylsiloxane films

The laser frequency dependence of the photon-stimulated desorption (PSD) of Rb atoms from surfaces prepared by adsorption of rubidium vapor on thin fi lms of polydimethylsiloxane (PDMS) was determined at low light intensities and at room temperature to have a threshold energy of 11 100 cm(-1). The de sorption of Rb follows the same functional dependence on laser frequency an d intensity as that found for Na and Na-2, where thresholds of 9500 and 11 500 cm(-1) were determined, respectively, and where a charge transfer model for the adsorbed species could successfully explain the 2000 cm(-1) differ ence in energy thresholds. (C) 2000 Elsevier Science B.V. All rights reserv ed.