Adsorption and reaction of a state-selected hydroxyl radical molecular beam with catalytic surfaces

A unique high intensity, high purity molecular beam of hydroxyl (OD) radicals was developed. This beam was used to investigate hydroxyl mediated surface chemistry on both Pt(111) and Au(111). The adsorption and desorption behavior was investigated on both single-crystal surfaces. Reaction of OD with coadsorbed CO and H₂ was studied on Pt(111). Reaction of OD with coadsorbed alkenes was studied on Au(111).; Chapter 1 is an introduction describing previous studies on both the platinum and gold systems. The metals' role in catalytic surface science is explained.; Chapter 2 contains a brief description of the molecular beam machine used to produce the hydroxyl radical molecular beam and perform the surface experiments reported here. It describes in full other equipment I have designed and constructed to aid in these studies.; A series of experiments involving OD radicals on Pt(111) is described in Chapters 3 and 4. Chapter 3 includes reaction between OD coadsorbed with CO whereas chapter four includes reaction between OD coadsorbed with H ₂. The activation energy for hydroxyl disproportionation is reported. Reaction mechanisms for water formation are discussed.; Abstraction reactions are studied in Chapter 5 with an oriented hydroxyl radical molecular beam and a Pt(111) surface. The branching ratio between Finally, in Chapter 6 OD adsorption and reaction with alkenes on Au(111) is reported. OD was proposed as a possible oxidant in catalytic selective oxidation experiments but was not observed to react with the alkenes studied. Oxygen left behind on the Au(111) surface following hydroxyl disproportionation was observed to react with propylene but not ethylene on the surface. Only complete combustion products H₂O and CO₂ were observed. The activation energy for hydroxyl disproportionation is reported.