https://doi.org/10.1351/goldbook.08241
Spectrometer in which beams of electromagnetic radiation from the source reach the detector via two paths, one through the sample and the other through a reference.
Notes:
- The radiant power in each beam is measured at each wavenumber.
- The output of a double-beam spectrometer is termed a double-beam spectrum. The ordinate of a double-beam spectrum is related to the radiant power that reaches the detector in the sample beam divided by that in the reference beam. The spectrum has a flat baseline where the sample does not absorb.
- The reference is usually a material having the same composition as the sample but lacking the analyte.