Reactions of sodium clusters with water clusters

In a crossed molecular beam experiment, the reactive scattering of sodium clusters Na(n) (n less than or equal to 21) with water clusters (H(2)O)(m) (m less than or equal to 40) is investigated. By measuring the angular and the velocity distributions of the scattered reaction products, direct information on the reaction mechanisms is obtained. The sodium clusters are generated in a supersonic expansion of sodium vapor from an oven with a refilling system with argon carrier gas. The products are detected by photoionization at wavelengths of 308 and 355 nm and mass analyzed in a time-of-flight mass spectrometer (TOF-MS), In addition, a fast chopper with a pseudorandom sequence modulating the sodium cluster beam allows us to determine at the same time the velocity distributions of the products. The scattering of Na clusters with H(2)O clusters shows only one series of reaction products, that is, solvated sodium atoms Na(H(2)O)(m) (m less than or equal to 32) with maximum intensities at m = 4, 5, 6. For all products, the measured angular and velocity distributions exhibit the formation of a complex that is stabilized by isotropic evaporation of water molecules. The detected products have low translational energy. Products containing NaOH have not been observed.