THE CHLORINE-35 NQR SPECTRUM OF SODIUM DICHLOROACETATE

In a previous investigation it was found that the chlorine-35 NQR spec trum of sodium dichloroacetate (NADCA) is complex and covers a more th an 2-MHz-wide frequency range. The study of the spectrum's temperature dependence shows no significant change between 77 K and 228 K except for the standard drift due to thermal motion and a steady decrease of the signal-to-noise ratio. The complexity of the spectrum is an indica tion that the crystal structure, apparently unreported so far, is also complex. Analysis of the spectral widths in a series of mono-, di-, a nd trichloroacetic acids, and of their alkali and alkaline earth metal salts leads to the conclusion that molecular interactions, a great se nsitivity of the dichloro group to these interactions, and a complex c rystalline structure are likely at the origin of the large width of th e spectrum in NADCA and related compounds. No structural phase transit ion is observed in the NADCA NQR spectrum over the temperature range s tudied, which is confirmed by the absence of any anomalies in the diff erential thermal analysis results.