Coadsorption of Co and C6H6 on Pt(111) Surfaces Studied by Ir-Reflection and Thermal Desorption Spectroscopy

Abstract

By means of IRS and TDS coadsorption of CO and C6H6 has been studied at 300 K on Pt (111) surfaces cleaned in ultrahigh vacuum (UHV). The effects depend on the order in which the Pt surface is exposed to both gases: When the surface is first exposed to C6H6 subsequent CO exposures displace C6H6 molecule from the surface. Preexposure with CO and subsequent C6H6 exposures produce a coadsorption phase in which CO is probably not bonded with its molecular axis normal to the Pt surface. In the presence of coadsorbed C6H6 the CO stretch vibration band shifts down in wavenumber from about 2090 cm−1 (for pure CO on Pt) to about 2060 cm−1.