The vibrational spectrum of sodium bromate

Abstract Sodium bromate is one of the few crystals which incorporate polyatomic ions in their structure and in which all the normal modes of vibration of the lattice are either Raman or infra‐red active. Thus it is an ideal meterial for investigation by the techniques of vibrational spectroscopy. Infra‐red and Raman spectra recorded at various temperatures between 15K and 300K over the frequency range 20 cm −1 to 1000 cm −1 are reported here from which a complete assignment of the zero wave vector modes is made. The results allow a test of the validity of the Lyddane‐Sachs‐Teller (LST) relationship in a fairly complex crystal with a large number of vibrational modes. Comparison of the results with those obtained in this laboratory and by other workers [1, 2] on NaClO 3 leads to the tentative assignment to roatatory and translatory character of the low frequency modes.