Results for the binding of carbon monoxide and oxygen along with the oxidation of CO in the presence of atomic Au(-) have been obtained utilizing a fast-flow reactor mass spectrometer. In addition, density functional calculations have been performed to explain the experimental findings. It was observed that upon oxygen addition to the metal plasma, gold oxide species of the form AuO(n)(-), where n = 1-3, were produced. The addition of carbon monoxide to the preoxidized gold atom revealed that AuO(-) and AuO(3)(-) promote the oxidation of CO. Density functional calculations on structures and their energetics confirmed the experimental findings and allowed us to propose mechanisms for the oxidation of carbon monoxide. The reactions of CO with AuO(1,3)(-) proceed via complex formation with CO bound to the oxygen atom, followed by either cleavage of the Au-O bond or complex rearrangement to form a weakly bound CO(2) unit, leading in both cases to the emanation of CO(2).

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Contents 1. Introduction 4039 2. Cluster Types and Production 4040 3. Experimental Methods Using Laser Spectroscopy 4041 4. Ionization Processes in Clusters 4042 A. The Formation of Protonated Ammonia Clusters: A Paradigm 4042 B. The Phenomenon of Coulomb Explosion 4042 a. Quantifying Coulomb Explosion 4043 b. Direct Evidence for the Role of Clusters in the Coulomb Explosion Process 4045 c. Consideration of Models of Coulomb Explosion 4046 d. Ionization Dynamics and Coulomb Explosion: Chemical Applications 4048 5. Cluster Solvation Effect on Reaction Dynamics 4048 A. Excited-State Proton Transfer 4049 B. Electron-Transfer Reactions 4051 C. Caging Dynamics 4053 6. Outlook 4054 7. Acknowledgment 4055 8. References 4055

A study of the excited-state dynamics of (SO2)m clusters following excitation by ultrafast laser pulses in the range of 4.5 eV (coupled 1A2, 1B1 states) and 9 eV (F band) is presented. The findings for the coupled 1A2 and 1B1 states are in good agreement with published computational work on the properties of these coupled states. A mechanism involving charge transfer to solvent is put forward as the source of the excited-state dynamics that follow the excitation of the SO2 F band within (SO2)m+1 clusters with m > 1. The proposed CTTS mechanism is supported by calculations of the energetics of the process and the observed trends in the excited-state lifetimes that correlate very well with the calculated energies.