Interaction of light and surface plasmon polaritons in Ag islands studied by nonlinear photoemission microscopy.

Two photon photoemission microscopy was used to study the interaction of femtosecond laser pulses with Ag islands prepared using different strategies on Si(111) and SiO₂. The femtosecond laser pulses initiate surface plasmon polariton (SPP) waves at the edges of the island. The superposition of the electrical fields of the femtosecond laser pulses with the electrical fields of the SPP results in a moiré pattern that is comparable despite the rather different methods of preparation and that gives access to the wavelength and direction of the SPP waves.

Space charge effects in photoemission electron microscopy using amplified femtosecond laser pulses.

Linear and nonlinear photoemission microscopy is used to study the origin of space charge effects that are frequently observed if amplified femtosecond lasers are used for generation of photoelectrons. Space charge effects are apparent in the width of the photoemission spectra, but also create image blur. The onset threshold for space charge effects is determined by recording the width of photoemission spectra and by finding the conditions under which spectral broadening is just less than the energy resolution of the microscope.