Study on the Eucalyptus and Poplar by generalized two-dimensional infrared correlation spectroscopy

Poplar and Eucalyptus were identified fast by Fourier transform infrared spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy (2D) in the present paper. The two kinds of wood were similar to each other in one-dimensional IR spectra but quite different in 2D FTIR spectra. In the range between 800 and 1 500 cm(-1), they are similar and three strong auto-peaks were aroused around 1221, 954 and 879 cm(-1) in synchronous spectrum and four weak auto-peaks were aroused around 1470, 1 150, 1 105 and 1008 cm(-1), respectively. In the range between 1500 and 1800 cm(-1), one strong auto-peak appeared with Poplar around 1 665 cm(-1) and one weak auto-peak appeared around 1 600 cm(-1) in synchronous spectrum. They fromed one pair of cross-peaks, whereas three auto-peaks not only at 1 650 cm-1 but also at 1 725 and 1600 cm-1 appeared with Eucalyptus and they became one 3 X 3 peak cluster. In addition, Eucalyptus has two weak auto-peaks at 1580, 1 510 cm-1 and four negative cross-peaks at 0 725 and 1 580 cm-1), 0 650 and 1 580 cm-1), (1 600 and 1 580 cm-1) and 0 510 and 1 580 cm-1) and three positive cross-peaks at (1 725 and 1 510 cm(-1)), 0 650 and 1 510 cm-') and Q 600 and 1 510 cm-'), respectively, which suggests that corresponding absorbance bands of Eucalyptus are more susceptive to the thermal perturbation than that of Poplar. The difference of 2D correlation between Eucalyptus and Poplar was obvious. The results proved that 2D correlation spectra could enhance the resolution of infrared spectra and increase the capacity of identification, which make it a powerful, rapid and new approach to identifying Eucalyptus and Poplar.