Design and performance of a reflectron based time-of-flight secondary ion mass spectrometer with electrodynamic primary ion mass separation

Abstract

In many secondary ion mass spectrometry (SIMS) investigations, the total number of generated secondary ions is limited by the amount of sample material available. This is the case in surface reaction studies as well as in organic and inorganic trace analysis or imaging SIMS. In such cases a time-of-flight mass spectrometer has some considerable advantages: quasisimultaneous detection of all masses, unlimited mass range, and very high transmission. We have developed a high-resolution reflectron based time-of-flight secondary ion mass spectrometer with a new electrodynamic mass separation and beam chopping technique based on a pulsed 90° deflection of the primary ion beam. A primary ion pulse width of less than 1.5 ns has been obtained. Second-order energy focusing in the flight path of the secondary ions is achieved by a two-stage reflectron. A mass resolution m/Δm=13 000 and a dynamic range of five orders of magnitude have been obtained with this instrument.