The Raman spectrum of sodium iodide at 1084 K

The vapour-phase Raman spectrum of an alkali is reported. Bands attributable to sodium iodide monomers (240 cm−1) and dimers (204 and 224 cm−1) are present at 1084 K. The intensity ratios of the bands reflect the relative abundance of the species in the vapour phase at this temperature. Normal coordinate analysis was carried out to determine the position of the low-frequency Raman-active band. The results are compared with those of previous calculations. Values for the heat capacity,Cp0, enthalpy,HT0-H2980, and entropy,ST0-S00, of gaseous Na2I2 have been calculated by the methods of statistical mechanics.