ABSTRACT
The gratings applied in the monochromators of spectrophotometers all work in the reflection mode. For the spectrophotometric measurements monochromatic or at least approximately monochromatic light with a bandwidth restricted to the narrowest possible wavelength region is needed. However, when precision measurements are carried out, or extreme alteration of temperature can be expected, it is advisable to use a thermostatted cell housing or cell holder. Recording spectra as well as quantitative measurements with more demanding requirements can only be performed by using a spectrophotometer; the light applied here for the measurement is produced by a monochromator. Reference beam changes as a function of the wavelength during the recording of the spectrum. These changes are due to the dependence of the energy output of the light source on the wavelength and the light absorption of the optical system. The light absorption is recorded on the ordinate almost exclusively in the form of absorbance or some other related function.
