Infrared reflection absorption spectroscopy study of smectite clay monolayers

Robin H A Ras, József Németh, Cliff T. Johnston, Imre Dékány, Robert A. Schoonheydt*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)


Infrared reflection absorption spectroscopy (IRRAS), also called infrared external reflection spectroscopy, is used for studying ultrathin hybrid clay films prepared by the Langmuir-Blodgett (LB) method. Infrared spectra of the hybrid films have been obtained at the air-water and air-solid (gold) interface. The presence of a smectite monolayer is observed when cationic surfactants are spread over the surface of a dilute aqueous smectite clay suspension. The in-plane ν(Si-O) band of saponite is observed in IRRAS spectra of saponite clay monolayers at the air-water interface. In contrast, the out-of-plane ν(Si-O) band at 1063 cm-1 is the dominant band in the p-polarized IRRAS spectra of a saponite monolayer deposited on a gold surface. These data correspond to the first-reported infrared spectra of clay minerals showing the enhancement of the out-of-plane vibrational modes and the nearly complete suppression of the in-plane vibrational modes. The results provide direct spectroscopic evidence confirming the orientation of the smectite particles parallel to the substrate.

Original languageEnglish
Pages (from-to)291-294
Number of pages4
JournalThin Solid Films
Issue number1-2
Publication statusPublished - 1 Nov 2004
MoE publication typeA1 Journal article-refereed


  • Blodgett films
  • Clay
  • Infrared spectroscopy
  • Langmuir


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