CLUSTER ISOLATED CHEMICAL-REACTIONS - EVIDENCE FOR THE FORMATION OF BA2O IN OXIDATION REACTIONS OF BARIUM DIMERS

The present paper reports on a new experimental technique, the cluster isolated chemical reaction technique. A single pair of reactants (or a controlled number of reactants) is isolated on a large atomic or mol ecular cluster. The reactants are free to migrate and to collide with each other on the cluster surface. The collision between two reactants results in a chemical reaction and yields observable signals, the clu ster playing the role of a reaction medium of finite size. The CICR te chnique is used here to study the reaction Ba-2 + N2O on (N-2)(8000) c lusters and the reaction Ba-2 + CO2 on (Ar)(5500) clusters, Both these reactions are chemiluminescent and yield rather unstructured emission spectra. The power of the CICR method is exemplified here since it al lows unambiguous determination of the emitter as Ba2O in both reaction s. This allows us to identify, then, the yet unassigned chemiluminesce nce spectrum observed by West et al. (J. Chem. Phys. 1977, 66, 2139) i n flames of Ba/CO2 and Ba/CO mixtures.