Oxygen isotope exchange between adsorbed NO and SrTiO3 surfaces

By using temperature-programmed desorption gas analysis, thermal desorption (TD) of (NO)-O-16 with a small amount of (NO)-O-18 was observed in the temperature region 350-800 K after 10(2)-10(4) L (NO)-O-18 exposure at room temperature (RT) on SrTiO3 powders. By using FTIR spectroscopy, the adsorption of (NO)-O-16 at RT (similar to 10(5) L) produced main IR bands at 958, 1101, and 1260 cm(-1) (tentatively assigned to NO2 species), which almost disappeared after heating up to 390 K under high vacuum. Thus, oxygen exchange between (NO)-O-18 and (SrTiO3)-O-16 may occur through an NO2-type intermediate on the surfaces involving of a lattice oxygen to produce the TD peak at 430 K. (C) 1999 Elsevier Science B.V. All rights reserved.