In spectrophotometry, a monochromator is a key component that selects a single wavelength of light from the light source.
Role of a Monochromator:
- Wavelength Selection
- The light source emits a range of wavelengths (white light or broad-spectrum light).
- The monochromator isolates only one specific wavelength to pass through the sample.
- Improves Accuracy
- Measuring absorbance at a single wavelength ensures that the reading is specific to the substance being analyzed.
- Prevents interference from other wavelengths.
- Controls Resolution
- The monochromator allows adjustment of the bandwidth — narrow bandwidth improves precision in detecting peaks.
- Enables Scanning
- In some spectrophotometers, the monochromator can scan across a range of wavelengths to produce an absorbance spectrum.
In short:
The monochromator’s role is to filter the light so that only the desired wavelength reaches the sample, making spectrophotometric measurements accurate and specific.