NIR spectroscopy of woods from Eucalyptus globulus

The origins of bands in the near-infrared (NIR) spectra of woods from Eucalyptus globulus have been investigated by using a number of approaches. The bands in the spectra have been compared with those in the spectra of eucalypt cellulose, glucuronoxylan, milled wood lignin and hot water extractives, and with bands removed from the wood spectra by treatment of the woods with sodium chlorite and with weak alkali. Furthermore, correlations have been obtained between the absorbances of bands in the NIR spectra and a) the hot water extractives and lignin contents of the woods and b) the absorbances of bands in the mid-infrared (MIR) spectra of the same woods. Many partial correlations were found showing a high degree of intercorrelation between the bands and confirming that the NIR bands arose from combinations of several fundamental bands.