Raman spectroscopy at temperatures between 298 and 423 K and at 77 K of kaolinites intercalated with formamide

Raman spectra of kaolinite and of the formamide-intercalated kaolinite were obtained at both 298 and 77 K using a Raman microprobe equipped with a the rmal stage. Upon cooling to 77 K, the band attributed to the inner hydroxyl shifts by 5 cm(-1) to lower wavenumbers and the bands assigned to the inne r surface hydroxyls move to higher wavenumbers. Upon intercalation of the k aolinite with formamide, an additional Raman band attributed to the formati on of a hydrogen-bonded complex between the inner surface hydroxyls and the carbonyl group of the formamide is observed at 3627 cm(-1) at 298 K and at 3631 cm(-1) at 77 K. Raman spectra of the deintercalation of the formamide -intercalated kaolinite are obtained by using the thermal stage to heat the intercalated kaolinite in situ. A decrease in intensity of the bands forme d through intercalation and at the same time an increase in intensity of th e inner surface hydroxyl bands are observed. A loss of intensity of the low -wavenumber region of the formamide-intercalated kaolinite is also observed .