Bridging the pressure gap: The development of a far-IR RAIRS high pressure cell

Far-infrared light, which can probe the vibrations of chemisorption bonds, is not absorbed by many catalytic feed gases and is therefore ideally suited to study surface chemistry in the presence of such gas. We describe a new instrument for conducting in situ synchrotron reflection–absorption infrared spectroscopy at pressures up to at least 1 atmosphere on samples which can be prepared and characterised pre- and post-reaction by conventional UHV surface science techniques. The system performance is illustrated by the oxidation of Cu(1 0 0) under 200 mbar of oxygen. Cu2O begins to grow at 390 K and is the only oxide detectable up to 508 K. Only when the substrate temperature exceeds 508 K does oxidation proceed to CuO.