Imaging nanostructures with scanning photoionization microscopy

Abstract

We report detailed studies of local electronic properties in nanostructured thin metallic films using scanning photoionization microscopy. This novel form of microscopy combines the advantages of diffraction-limited optical excitation with the ability to detect both photons and low kinetic energy photoelectrons, permitting sensitive characterization of heterogeneous surfaces under vacuum conditions. Using this technique, correlated measurements of multiphoton photoemission cross section and optical penetration depth are reported for Au films supported on Pt. These results present a first step toward combining confocal fluorescence or Raman microscopy with time-resolved photoelectron imaging spectroscopy in complex metal film environments, which should be ideally suited to investigating local plasmonic effects in nanostructures.

Single nanoparticle plasmonics

“…15,112 PEEM, however, can be a complex tool requiring sophisticated electron optics and special care to avoid distortions due to charging. A diffraction-limited variant of the technique, scanning photoionization microscopy (SPIM), has been developed and used to study the behaviour of plasmonic particles such as rods and cubes; 80,[113][114][115] its high temporal resolution and relative simplicity are prominent advantages.…”

Influence of electrostatic fields on molecular electronic structure: insights for interfacial charge transfer

“…82,83 Significant efforts have also gone into developing photoelectron spectroscopy with simultaneously high spatial and energy resolution, ranging from time-of-flight photoemission electron microscopy to spatially resolved photoionization microscopy. [84][85][86][87][88] Although some of these techniques are still in their infancy, new insights on the local environment and potentially the electrostatics may be anticipated. Certainly, the growth of highly uniform heteroepitaxial thin films, although likely unrealistic for real devices, provides a helpful first step in limiting the influence of electrostatic site-dispersion as well.…”

Observation of Nanosecond Hot Carrier Decay in Graphene

“…The setup is very similar to the velocity map imaging (VMI) method, which was conventionally used in gas-phase measurements of photoionization and photodissociation dynamics . We note that there have been great efforts − in transferring the conventional VMI method from gas phase to surface studies. However, the 3D capability has been lacking until this work.…”