Two-photon photoemission spectroscopy at clean and oxidized Cu(110) and Cu(100) surfaces

Abstract

Two-photon photoemission spectra of Cu(110) and Cu(100) are measured using ∼ 3.2 eV excitation laser with ∼ 20 fs pulse width. The spectra are measured as a function of laser polarization, excitation energy, bias voltage, and oxygen coverage. They are discussed in terms of the bulk and surface electronic structure of Cu and hot electron relaxation dynamics, and compared to previous nanosecond laser studies. In addition, three-photon photoemission through the n = 1 image potential state on Cu(100) is observed.