UV-VIS Spectroscopy:
The limitations of fixed-wavelength in a single-beam spectrophotometers are minimized by using a double-beam spectrophotometer as shown in Figure 37.06. A chopper, having known speed of rotation controlled by signal processer, controls the radiation's path, alternating it between the sample, the blank, and a shutter.
Figure 37.06: Schematic diagram of double-Beam Spectrophotometer.
This process resolves the signal reaching the detector through blank, P0 , and the sample, PT .
The effective bandwidth of a double-beam spectrophotometer is controlled by adjusting the monochromator's entrance and exit slits.
A continuous scanning monochromator allows for the automated recording of spectra. Double-beam instruments are more versatile and useful for both quantitative and qualitative analyses.