Crystalline-field effects on the infrared and Raman spectra of powdered alkali-metal, silver, and thallous nitrates

Infrared and Raman spectra have been recorded for room-temperature-phase, powdered samples of LiNO 3 , NaNO 3 , KNO 3 , RbNO 3 , CsNO 3 , AgNO 3 , and TlNO 3 . For the trigonal systems, the nitrate pairs LiNO 3 , NaNO 3 and RbNO 3 , CsNO 3 give almost identical spectra. For the orthorhombic systems, AgNO 3 and TlNO 3 give similar spectra, whereas that of KNO 3 is significantly different. Site and correlation field perturbations are considerably more pronounced in the antisymmetric stretching region (ν 3 ca. 1400 cm −1 ) than in the antisymmetric bending region (ν 4 ca. 700 cm −1 ). Although lifting of the degeneracy of E′ modes was frequently observed, the reported split of the ν 4 (E′) mode (ca. 716 cm −1 ) of the aragonite form of KNO 3 could not be confirmed. Multiple internal reflectance techniques have been employed to observe the extremely intense ν 3 (E′) infrared fundamental ca. 1400 cm −1 .