Electronically Stimulated Desorption: Mechanisms, Applications, and Implications

Abstract

To a varying degree, virtually all surface spectroscopies and microscopies using electrons, photons and/or ions suffer from beam damage effects. These can become so important that they effectively limit the obtainable resolution and/or sensitivity in a particular application. In a large fraction of applications, these beam-induced effects are the eventual consequence of primary electronic excitations, a term which will be used to include ionization. One of the possible final consequences is the release of surface particles into the vacuum, i.e. “Electronically Stimulated Desorption” (ESD; this term is used here to include electronic stimulation by photon absorption) or “Desorption Induced by Electronic Transitions” (DIET). This is a subject which has been studied in its own right for over 25 years now and has contributed considerably to the basic knowledge about surface and adsorbate excitations, their coupling to the bulk, their screening, delocalization, and deexcitation^1–4. In the subject context of this volume, as well as in other practically important cases, such as total and partial pressure measurements, ultimate attainable vacuum or gas purity in UHV systems enclosing energetic particles — in particular plasma devices and accelerators/storage rings — these processes have a negative importance, as disturbing effects to be avoided: which is easier if their mechanisms are understood.