https://doi.org/10.1007/s100530170114
Diffusion and aggregation of Agn-clusters (n = 2-9) on HOPG probed by fs-two-photon-photoemission
1
Heinrich-Hertz-Institut für Nachrichtentechnik Berlin GmbH, Einsteinufer 37, 10587 Berlin, Germany
2
Université Claude Bernard Lyon 1, Bâtiment Kastler, 69622 Villeurbanne Cedex, France
3
Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
4
Technische Universität Ilmenau, Institut für Physik, Weimarer Strasse 32, 98693 Ilmenau, Germany
Corresponding author: a ulrike.busolt@hhi.de
Received:
30
November
2000
Published online: 15 September 2001
The diffusion and aggregation of preformed Agn-clusters 
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.
PACS: 68.43.Jk – Diffusion of adsorbates, kinetics of coarsening and aggregation / 36.40.Sx – Diffusion and dynamics of clusters / 78.67.-n – Optical properties of nanoscale materials and structures / 36.40.Gk – Plasma and collective effects in clusters
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001
