Skip to main content

Differing effects of particle size and shape in the infrared and Raman spectra of kaolinite

Buy Article:

$13.61 plus tax (Refund Policy)


Infrared (IR) spectra of well-ordered kaolinites generally show four OH-stretching frequencies, near 3697, 3670, 3652 and 3620 cm-1. Raman spectra of the same kaolinites mostly show an additional band near 3686 cm-1, which, in the coarsely crystalline Keokuk kaolinite, largely replaces the 3695 cm-1 band. It is shown that the 3686 cm-1 band can be ascribed to a transverse optical crystal vibration involving the in-phase stretching vibration of the three inner-surface hydroxyl groups in the unit-cell. Raman exciting radiation, commonly of wavelength near 500 nm, can excite this crystal vibration in crystals of comparable and greater thickness. Infrared studies are usually made on clay-size (<2 m) particles, which have mean thicknesses of 30-150 nm. Infrared radiation of wavelength near 2.7 m can only excite whole crystal vibrations perpendicular to the plates. The in-phase vibration of inner-surface OH groups in the whole-crystal mode lies at 3697 cm-1, which is the same frequency as that of the longitudinal optical mode in macroscopic crystals.

Document Type: Research Article


Affiliations: Soil Science Group, Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH, UK

Publication date: December 1, 1998

More about this publication?

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more