Experimental methods

Abstract

In this chapter some experimental methods of cluster science will be treated. Stress will be laid on representative examples, not on an exhaustive discussion. Most of the chapter will deal with the various sources used to produce clusters. Despite intense developments in the last years, this is still a difficult enterprise. New types of cluster sources are constantly developed. Some examples only will be discussed here. Problems with detectors for cluster ions are treated in Section 3.2. Electron diffraction from a cluster beam is discussed in Section 3.3. Methods to produce neutral mass selected clusters are reviewed in Section 3.4. Section 3.5 contains a brief overview of different types of mass spectrometers. Methods for optical and electron spectroscopy are discussed in 3.6 to 3.8. A very simple experiment is shown in Fig. 1. The clusters are generated using a supersonic jet. They traverse a skimmer, are ionized by electron or photon impact, are separated according to their mass by a mass spectrometer, and are registered after having hit a detector. The different components of this apparatus will be discussed in detail below. Some more sophisticated set-ups for experiments on mass selected clusters are discussed in 3.5.