What is a diffraction grating used for in spectrophotometry?

A diffraction grating is an essential component in spectrophotometry, primarily utilized for its ability to separate light into its component wavelengths. When light passes through a diffraction grating, it encounters a series of closely spaced slits or grooves. This configuration causes the light waves to interfere with one another, resulting in constructive and destructive interference patterns. The effect of this interference is the production of a spectrum, where different wavelengths of light are spread out spatially.

This ability to produce a spectrum is crucial for identifying the unique absorption characteristics of various substances when they are examined in the spectrophotometer. By analyzing the resultant spectrum, scientists can determine the concentration of specific compounds in a sample by measuring the intensity of light at specific wavelengths that corresponds to the samples’ absorption.

While the other functions related to the light source, focusing light, and measuring absorbance are important in a spectrophotometric system, they do not specifically pertain to the role of the diffraction grating. The grating's primary function is to create the spectral output necessary for analysis, making the option about producing a spectrum through slits the most accurate description of its use in this context.