VIBRATIONAL SPECTROSCOPY OF AMMONIATED SODIUM-IONS - NA+(NH3)M, M = 6-12

Vibrational spectra of Na+ (NH3)M, M = 6-12, in the region from 1020 to 1090 cm-1 (9.6-mu-m band of the CO2 laser) are reported. The spectra, associated with the nu(2) mode of NH3, reflect the influence of the Na+-NH3 and NH3-NH3 interactions. From the spectral dependence on cluster size, it appears that six ammonia molecules form the first solvent shell about the Na+ ion. Ammonia molecules in a bulklike environment appear for ammoniated sodium ions with 10 or more solvent molecules.