Raman studies of sodium fluoroborate single crystals

Abstract

Raman spectra of oriented single crystals of NaBF, were measured at 77 and 298 K. The number of bands and the intensities were in excellent agreement with the unit cell group predictions for the known crystal structure, Di2, Z = 2. The results for the vl, v2 and v, regions were in excellent agreement with those of Bates [ J . Ckm. Phys. 55, 489 (1971)l. A recent study by Rajakumar et al. [J. Ramm Spectrosc. 23, 75 (1992)l is erroneous. The new measurements permitted the assignment for the Raman bands in the vj region. Peaks in the external mode region were very weak because both the Na' and BF,-ions have spherical symmetry, small polarizabilities and small polarizability derivatives with respect to normal coordinates. Only three weak peaks of the nine predicted externalmodes were observed (88 cm-', A,; 110 cm-', &; and 214 cm-', B2,). Crystals grown from aqueous solution were found to contain water and as much as 0.1% of BF,OH-as a substitutional impurity. Peaks due to the 0-H (0-D) stretching vibration were detected in the crystals at 3641 (2688) cm-' and peaks due to the B-OH (BOD) stretching vibration were detected as 773 (748) cm-'.

Spectroscopy of Hydrothermal Reactions. 2. Reactions and Kinetic Parameters of [NH3OH]NO3 and Equilibria of (NH4)2CO3 Determined with a Flow Cell and FT Raman Spectroscopy

“…The peaks at 1064 and 1380 cm -1 in the lower temperature spectra are attributable to aqueous CO 3 2-. Aqueous NH 2 CO 2contributes a Raman shift 30 at 1035 cm -1 , which is resolved from the multiplet in the 1000-1070 cm -1 region. The HCO 3ion produces a C-OH stretching frequency at 1017 cm -1 and a C-O stretch at 1360 cm -1 at 293 K. These HCO 3modes gradually decrease in energy with increasing temperature and are 994 and 1344 cm -1 , respectively, at 450 K. ν 2 (H 2 O) appears as a broad shift centered at about 1650 cm -1 and is relatively unaffected by temperature in this range.…”