TRANSMISSION MICRO-INFRARED SPECTROSCOPY - AN EFFICIENT TOOL FOR MICROSCALE CHARACTERIZATION OF COAL

Fourier transform infrared (FT-i.r.) micro-scale analysis of organic matter can be applied to evaluate the heterogeneity and to characterize the individual petrographic components of coal. Suitable sample preparation development was required to benefit from the potential advantages of this technique. Sections of coal (10-20-mu-m thick) have been prepared by slightly modifying the polished thin section preparation or by using a wire saw. Ultramicrotome sections (0.5-1.5-mu-m thick) were also designed. The micro-FT-i.r. spectra display good signal to noise ratio and a good individualization of bands. Advantages of the microspectroscopic technique over the KBr pellet global mode are: better spectral quality; the absence of adsorbed water; and better quantitative results. The limitations of the method are also discussed with special emphasis on the effect of coal mineral content. Applications of micro-FT-i.r. to characterize coal macerals and alteration phenomena are presented.