Raman spectroscopy of potassium acetate-intercalated kaolinites at liquid nitrogen temperature

Raman microscopy has been used to study low and high defect kaolinites and their potassium acetate intercalated complexes at 298 and 77 K. Raman spect roscopy shows significant differences in the spectra of the hydroxyl-stretc hing region of the two types of kaolinites, which is also reflected in the spectroscopy of the hydroxyl-stretching region of the intercalation complex es. Additional bands to the normally observed kaolinite hydroxyl stretching frequencies are observed for the low and high defect kaolinites at 3605 an d 3602 cm(-1) at 298 K. Upon cooling to liquid nitrogen temperature, these bands are observed at 3607 and 3604 cm(-1), thus indicating a weakening of the hydrogen bond formed between the inner surface hydroxyls and the acetat e ion. Upon cooling to liquid nitrogen temperature, the frequency of the in ner hydroxyls shifted to lower frequencies. Collection of Raman spectra at liquid nitrogen temperature did not give better band separation compared to the room temperature spectra as the bands increased in width and shifted c loser together. (C) 2001 Elsevier Science B.V. All rights reserved.