Near Infra-Red (NIR) Spectroscopy
The NIR spectra of juvenile (rings < 8) and mature (rings >
24) wood obtained from loblolly pine, between 350 – 2500
nm, is shown in figure 5. It is clear to see that differences
cannot be noted visually; the characteristic peaks show
broad overlapping absorption bands arising from secondary
overtones and combinations X-H stretching vibrational
modes. NIR is, most importantly, sensitive to hydrogen
bonding, thus making it very applicable to wood. The use of
multivariate statistical techniques improves the extraction of
information from the spectra, revealing any differences.