NEAR-FIELD TIME-OF-FLIGHT SPECTROSCOPY OF SODIUM ATOMS DESORBING FROMSURFACE-BOUND CLUSTERS

Delayed photodesorption of Na atoms from large, surface-bound Na clust ers is investigated with a novel technique that includes pulsed plasmo n excitation and continuous Doppler-free two-photon evanescent wave de tection of desorbing atoms. The spatial confinement of the laser beams within the evanescent wave, the Doppler-free nature of the detection mode, and an accurate evaluation of the kinetic energy of the desorbin g atoms in terms of a multiphonon time-of-flight distribution allows t emporal information on the decay mechanisms within the cluster to be o btained. (C) 1996 Optical Society of America