Fig. 2.

Second derivatives of FT-NIR transmission spectra of spruce wood in the OH first overtone region assigned to alcoholic and phenolic OH groups (6,928 cm^-1) before (black line) and after (grey line) impregnation with deuterium oxide and differences (Δ NIR) between them (coloured line) demonstrate the accessibility of OH groups to deuterium oxide. The derivatives of the NIR spectra were vector normalised (VN) and show the lower number of OH groups due to polysaccharides degradation and a reduced accessibility of these groups in brown-rot wood with 16 % mass loss (a) compared to non-degraded spruce wood (b) Reproduced after Fackler and Schwanninger (2011) with permission from IM publications