Raman spectral studies of supersaturated bisulfate solution droplets

Abstract Raman spectra of supersaturated solution droplets of ammonium bisulfate, potassium bisulfate and sodium bisulfate were obtained in the region 800–1300 cm −1 with a resolution of 1 cm −1 . Under supersaturation condition, these solution droplets show new molecular vibrations, not found in the spectra of either the bulk crystalline or the solution samples. The results demonstrate the existence of an ion pair in the supersaturated bisulfate solution, which consists of both the cation and the anion of the dissociated solute as well as the solvent molecules. They also provide a new interpretation of the asymmetry commonly found in the 1050 cm −1 bisulfate ion vibration band.