the near-infrared (nir) region (defined by the astm working group on nir as 780 to 2526 nm, october 1985) was the first nonvisible portion of the spectrum to be found, in 1800, by herschel. the vibrational absorptions in the near-infrared are overtone and combination frequencies of absorption bands that occur in the mid-infrared. these overtones and combinations cause overlapping absorption bands, which make it more difficult to visually identify chemical groupings of a molecule from their near-infrared spectra than from the 'finger-print' region of the mid-infrared spectrum. the overtone and combination bands are one to three orders of magnitude weaker than the fundamental bands. this provides singularly useful sampling advantages. nir instrumentation development came earlier than mid-infrared, due to the availability of suitable sources and sensitive lead sulfide detectors. these factors led to substantial development of nir spectroscopy through the 1950s. nevertheless, interest in the near-infrared region faded in the 1960s, except for some users with specific analytical applications that are difficult to accomplish in the mid-infrared region. in time, nir analyses were applied to a limited number of specific problems, such as the on-line measurement of water in paper-making machines and the determination of hemoglobin and of oxygen saturation of hemoglobin in whole blood. near-infrared measurements were sometimes performed during this period on nir attachments, which become available for uv/visible spectrophotometers