Münster 1997 – wissenschaftliches Programm

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O: Oberflächenphysik

O 30: Chemische Oszillationen

O 30.5: Vortrag

Donnerstag, 20. März 1997, 12:15–12:30, S 2

A real time vibrational spectroscopic investigation of the oscillatory NO+CO reaction on Pt{100} — •J. H. Miners¹, R. Martin², R. Nalezinski¹, P. Gardner³, and A. M. Bradshaw¹ — ¹Fritz-Haber-Institut der Max-Plank-Gessellschaft, Faradayweg 4-6, 14195 Berlin — ²iRAS GmbH, Im Technologiepark 1, 15236 Frankfurt/Oder — ³The Department of Chemistry, UMIST, Manchester M60 1QD, England

The oscillatory NO+CO reaction on Pt{100} has received considerable attention during the last few years from both experimentalists and theoreticians. Although a range of techniques has been applied to this system, none of them has been able to show directly which species are present on the surface during the oscillatory cycle and, more importantly, at what concentration. Building on our previous studies of Pt{100}+NO, CO, NO+CO and CO+NO, we have carried out a real-time infrared reflection-absorption study of this system under oscillatory conditions in the 10⁻⁷mbar pressure regime. Specially adapted software, a time resolution of 3s, a spectral resolution of 4cm⁻¹ and a high S/N-ratio allow us to determine accurately the varying adsorbate concentrations of NO and CO during an oscillation cycle and relate them in phase to the formation of CO₂ and N₂. The results obtained are discussed in the light of recent kinetic models of this system.