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In this paper we present a combined STM, SEM and time-resolved PEEM study of silver clusters on a nano-patterned HOPG-substrate, exhibiting areas of different defect type and defect densities. The areas show small but distinct differences in the femtosecond dynamics associated with electronic excitations in the clusters. We assign these differences to variations in the cluster size distribution and variations in the cluster-substrate interaction as governed by the bonding to the different defect types. [ABSTRACT FROM AUTHOR]

The time-resolved two-photon photoemission technique (TR-2PPE) has been applied to study static and dynamic properties of localized surface plasmons (LSP) in silver nanoparticles. Laterally, integrated measurements show the difference between LSP excitation and nonresonant single electron-hole pair creation. Studies below the optical diffraction limit were performed with the detection method of time-resolved photoemission electron microscopy (TR-PEEM). This microscopy technique with a resolution down to 40nm enables a systematic study of retardation effects across single nanoparticles. In addition, as will be shown in this paper, it is a highly sensitive sensor for coupling effects between nanoparticles. [ABSTRACT FROM AUTHOR]

In combining time-resolved two-photon photoemission (TR-2PPE) and photoemission electron microscopy (PEEM) the ultra-fast dynamics of collective electron excitations in silver nanoparticles (localized surface plasmons – LSPs) is probed at fs and nm resolution. Here we demonstrate that the sampling of the LSP dynamics by means of time-resolved PEEM enables detailed insight into the propagation processes associated with these excitations. In phase-integrated as well as phase-resolved measurements we observe spatio-temporal modulations in the photoemission yield from a single nanoparticle. These modulations are assigned to local variations in the electric near field as a result of the phase propagation of a plasmonic excitation through the particle. Furthermore, the control of the phase between the fs pump and probe laser pulses used for these experiments can be utilized for an external manipulation of the nanoscale electric near-field distribution at these particles. [ABSTRACT FROM AUTHOR]

The dynamics of laser-excited electrons in elliptically shaped silver nano-particles is studied using time-resolved two-photon photo-emission. By changing the polarization of the laser pulse at a fixed frequency, a different dynamics is observed near and far from resonance. To analyze these data, the effect of radiation damping on Mie plasmons of Ag nano-particles is studied as a function of laser frequency and polarization. It is shown that the off-resonance lifetime can be shorter or longer than the lifetime at resonance, depending on the incidence conditions of the laser light and on the depolarization factors characterizing the optical response of the nano-particles. [ABSTRACT FROM AUTHOR]

Abstract. A new method for investigating the electron dynamics of free metallic nanoparticles suspended in a carrier gas is described. Monodisperse nanoparticles in the size range from 10 to 80 nm pass through a photoionization tube, where they are irradiated by a pump and a probe fs laser pulse. The nonlinear effect caused by the two photon photoionization process allows to study the inelastic lifetime of optically excited electrons in the intermediate state in the time domain by means of a crosscorrelation experiment. [ABSTRACT FROM AUTHOR]