PUB - Publikationen an der Universität Bielefeld

To observe the products of surface reaction mechanisms we combined a standard quadrupole mass spectrometer featuring high-speed scanning options with fast data acquisition and a computer-controlled sample heating system. This combination served to obtain a general view (like a 'fingerprint') of the reaction occurring on a Pt(100) crystal upon heating the adsorbate covered surface, as well as to allow for a detailed analysis of the gas compounds leaving the surface within a single measurement. The method is denoted by multimass thermal desorption spectroscopy (MTDS). The MTDS device is capable of recording 850 amu/s providing up to 15 complete mass spectra per second of 50 amu width while heating the surface linearly. The data contain the ion currents of both the reaction products and their fractions (cracking patterns) generated in the spectrometer. Thus it is possible to distinguish between gas species with equal mass numbers by subsequent numerical evaluation.