Multicoincidence studies of photo and Auger electrons from fixed-in-space molecules using the COLTRIMS technique

Abstract

This report will introduce the reader to the method of measuring electron and ion momentum distributions from fixed-in-space molecules using modified versions of the COLTRIMS technique. Following the introduction and a description of the working principles of this technique, a detailed discussion of the design of the electron and the ion detection part of the spectrometer will be presented. The actual measurement represents only a minor fraction of a COLTRIMS-like experiment. We therefore give an in-depth view at the basics of the offline-analysis for the field of detecting multiple particles from a Coulomb exploding molecule. Achievable resolutions, the possibilities of background suppression via multiparticle software coincidence methods, and the improvement of electron momentum resolution by center-of-mass-correction will be discussed, followed by an example of a setup for low energy electrons (¡10 eV). Apart from the introduction to the treatment of the acquired data, a recent development on the hardware of the spectrometer will be presented. We have for the first time used a retarding field in the spectrometer’s electron arm. This provides the possibility of measuring high energy Auger electrons of ∼ 300 eV. A typical implementation for an experiment on Auger electrons from fixed-in-space nitrogen will be shown. The article will close with examples of recent measurements of photoionization of fixed-in-space carbon monoxide.