Near infrared (NIR) spectroscopy has been used for
the characterization of different forms of biomass for
more than 15 years (Marten et al., 1985). The NIR portion
of the spectrum ranges between 750 and 2500 nm,
just above visible red. Absorption in this range provides
information on overtones of the bending and
stretching vibrations of C–H, O–H, and N–H bonds,
making the information in the spectrum useful for analyzing
the individual components in biological materials
(