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Diffusion and aggregation of Agn-clusters (n=2-9) on HOPG probed by fs-two-photon-photoemission

: Busolt, U.; Cottancin, E.; Socaciu, L.; Rohr, H.; Leisner, T.; Woste, L.


The European Physical Journal. D, atomic, molecular and optical physics 16 (2001), No.1-3, pp.297-300
ISSN: 1434-6060
ISSN: 1434-6079
International Symposium on Small Particles and Inorganic Clusters (ISSPIC) <10, 2000, Atlanta/Ga.>
Conference Paper
Fraunhofer HHI ()
aggregation; atomic clusters; graphite; metal clusters; photoelectron spectra; photoemission; silver; surface diffusion; time of flight spectra; two-photon spectra; diffusion; agn-clusters; hopg; fs-two-photon-photoemission; highly oriented pyrolytic graphite; ultrashort laser pulse pairs; kinetic energy; magnetic bottle type time-of-flight spectrometer; room temperature; nanoparticles; photoelectron yield; plasmons; photoelectrons kinetic energy distribution; quantum size effect; 100 k; 150 k; 298 k; ag; c

The diffusion and aggregation of preformed Agn-clusters (n = 2-9) deposited onto a highly oriented pyrolytic graphite (HOPG) substrate is studied by two-photon-photoemission (2PPE). The sample is irradiated with ultrashort laser pulse pairs and the kinetic energy of the emitted photoelectrons is analyzed in a magnetic bottle type time-of-flight spectrometer. During annealing of the sample from 100 K up to room temperature, nanoparticles are formed on the surface by diffusion and aggregation of the silver clusters. A steep increase of the total photoelectron yield at a sample temperature of about 150 K is explained by the excitation of plasmons in the silver nanoparticles. From the kinetic energy distribution of the photoelectrons we deduce a strong. variation of the work function of the sample during the formation of the nanoparticles, which is attributed to a quantum size effect.