RAMAN SPECTRAL PATTERN AND CHEMICAL COMPONENTS OF SATURATED SOLUTION OF AMMONIUM OCTAMOLYBDATE HYDRATE

摘要

Aiming at many controversial reports on Raman spectral pattern of octamolybdate ion in aqueous solution appearing in the literature, a new method for the establishment of corresponding relation between Raman spectral pattern and chemical components of aqueous molybdate solution was put forward using spectroscopy measure and component analyses of saturated solution of ammonium octamolybdate hydrate known structure. It was found that the main characteristic of Raman spectral pattern of the saturated solution was described as the same "double-peaks, hereinto a weak peak at the boundary" as some literature, but chemical components of the saturated solution were affirmed to be octamolybdate ion (Mo_8O_(26)~(4-)) and double protonated heptamolybdate ion (H_2Mo_7O_(24)~(4-)), which were in equilibrium in aqueous solution each other. The authors propose that the pattern of the saturated solution can be regarded as the standard pattern of primiparous octamolybdate ion during acidified molybdate solution. It is satisfying that the standard pattern is applied to the identification of primiparous octamolybdate ion during acidified molybdate solution.