ABSTRACT
Spectrophotometers for the ultraviolet (UV), visible (VIS),
and near-infrared (NIR) regions will be discussed in
this chapter. Typically, the UV region is considered
to extend from 190 to 350 nm, the visible region from
350 to 800 nm, and the NIR from 800 to 2500 nm.
However, considerable latitude can be found in the
definitions of these regions; the UV might extend up
to 400 nm and the short wavelength NIR (SWNIR) from
600 to 1100 nm. The total wavelength range from 190 to
2500 nm is equivalent to a frequency range of about
1015-1014 Hz, or a wavenumber range of 50,500-
4000 cm21. In this discussion, we will specifically define
the abscissa in terms of wavelength (l) in nm, although it should be pointed out that wavenumbers are often
used in the NIR.
