Time‐Resolved Two‐Photon Photoemission on Surfaces and Nanoparticles

Abstract

Time‐resolved two‐photon photoemission spectroscopy allows an insight to be gained into ultrafast dynamic surface processes. In this chapter, we first discuss the relaxation dynamics of excited electrons and holes for metals, and also describe the behavior of excitonic states on bandgap materials which show lifetimes well into the microsecond regime. Electron transfer processes to adsorbates are discussed for typical examples. New approaches for photoelectron imaging with time resolution are presented which extend time‐resolved investigations to localized dynamics on nanoparticles. Lifetime maps allow to study exciting prospects of propagation dynamics of surface plasmon polaritons with subfemtosecond resolution. Phase‐ and polarization‐ controlled optical fields also open a new area of nanoscopic dynamic studies with subwavelength spatial and femtosecond time resolution.

Light Localization and Magneto-Optic Enhancement in Ni Antidot Arrays

“…To provide direct evidence for the excitation of SPPs on magneto-plasmonic structures we use photoemission electron microscopy (PEEM). PEEM is a powerful technique for imaging the photoelectron distribution of the sample on a nanometer local scale. ,, More precisely, the electrostatic lens system offers a spatial resolution of 25–30 nm, beyond the optical diffraction limit, and is well-suited to image the distribution of the electric near-field within our nm-scaled antidot structure. As light sources for the microscope, we use a mode-locked Ti:sapphire laser oscillator with a photon energy of ℏω = 1.55 eV and its frequency-doubled fundamental mode with a photon energy of ℏω = 3.10 eV as well as a commercial optical parametric oscillator that provides variable photon energies between 1.55 and 3.59 eV.…”

One-step theory of two-photon photoemission

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] A widely used variant of time-resolved photoemission experiments is given by two-photon photoemission (2PPE). [16][17][18][19][20][21] A prominent application of 2PPE is to study ultra-fast demagnetization processes in magnetic solids. [22][23][24][25] Besides the general interest in such nonequilibrium phenomena, a variety of spectroscopic issues like dichroic phenomena, [26][27][28] spin-dependent life-times of electronic states, [29][30][31] quantum beats 32,33 or delaydependent spectral-line width 32,33 are of great scientific interest.…”