Formation of sodium hydroxide in multiple sodium-water cluster collisions

In a pickup arrangement, the reactive scattering of sodium atoms and dimers with water clusters (H2O)(m), m less than or equal to 140, is investigated. The water cluster beam is generated in a pure supersonic expansion and crosses an atmosphere of sodium vapor. The reaction produces are detected by photoionization at a wavelength of 360 nm (3.45 eV) and mass analyzed in a reflectron time-of-flight mass spectrometer. Doping the H2O clusters with Na atoms results in the formation of solvated sodium atoms Na(H2O)(m), representing the distribution of the pure water clusters. At higher sodium pressures also Na-2 dimers an produced, which then react in a second step with the solvated Na atoms to products of the type Na(NaOH)(2)(H2O)(m) and, to a lesser extent, also to Na(NaOH)(4)(H2O)(m). The size range follows that of the precursors with a pronounced maximum of intensities between m = 6 and 14 in the former case.