Module 7 : Optical properties Spectroscopy techniques
Lecture 37 : Introduction
UV-VIS Spectroscopy:
There are two types of UV-VIS spectroscopy: Single-beam spectrophotometer and double-beam spectrophotometer. In the first one, a filer photometer, which uses an absorption or interference filter to isolate a band of radiation, has a single optical path between the source and detector as shown in Figure 37.05.
Figure 37.05: Schematic diagram of Single-Beam Spectrophotometer.
Single-Beam instrument (Thermo scientific spectronic 20D+) is equipped with a fixed-wavelength monochromator as shown in Figure 37.05. This has a range of 340 – 625 nm.
Fixed wavelength single-beam spectrophotometers are not practical for recording spectra, as the adjustment of wavelength manually is quite awkward and time-consuming. The accuracy of a single-beam spectrophotometer is limited by the stability of its source and detector over time.