Introduction

Abstract

Photoemission Spectroscopy (PES) is one of the most extensively used methods to study the electronic structure of atoms, molecules, solids and adsorbates [1]. Its effectiveness stems from the fact that the method is relatively straightforward and that it allows the simultaneous determination of energy and momentum of electrons. In recent years the energy resolution of this method has been improved considerably, namely for experiments using UV radiation to about 1meV (corresponding to about 10 K), and in addition the energy resolution for experiments employing soft x-rays (1-5 keV) has reached values of about 50 meV. Both these improvements have opened new spectroscopic possibilities. In order to demonstrate the new domain in this field the editors of Springer Lecture Notes in Physics have suggested to document this new state of photoemission spectroscopy in a volume to allow the interested community a comprehensive view on this field.