UV Spectroscopy- Definition, Principle, Steps, Parts, Uses


Spectroscopy is the study of how matter interacts with electromagnetic radiation, such as light. Different types of spectroscopy use different regions of the electromagnetic spectrum to probe the structure, properties, and behavior of molecules. UV spectroscopy is a type of absorption spectroscopy that uses ultraviolet (UV) light, which has wavelengths between 200 and 400 nanometers (nm) .

Absorption spectroscopy measures how much light is absorbed by a sample at different wavelengths. When a molecule absorbs UV light, it gains energy and some of its electrons are promoted from lower to higher energy levels . The energy levels of the electrons depend on the molecular structure and the type of chemical bonds . Therefore, by analyzing the absorption spectrum of a molecule, we can learn about its structure and identify functional groups that absorb UV light .

UV spectroscopy is widely used in analytical chemistry for the qualitative and quantitative determination of various substances in a sample . For example, UV spectroscopy can be used to detect impurities, elucidate structures, measure concentrations, and study reaction kinetics of organic and inorganic compounds that have chromophores . Chromophores are parts of molecules that absorb light and give color to substances. Some common chromophores are double bonds, aromatic rings, carbonyl groups, and metal ions .

To perform UV spectroscopy, we need a device called a spectrophotometer . A spectrophotometer consists of several parts that work together to produce and measure the absorption spectrum of a sample . The main parts are:

  • A light source that emits UV light
  • A monochromator that selects a specific wavelength of light
  • A sample cell that holds the sample solution
  • A detector that measures the intensity of light after passing through the sample
  • A recorder that displays the spectrum as a graph of absorbance versus wavelength

In this article, we will discuss each part in more detail and explain how they function. We will also explore some of the applications and uses of UV spectroscopy in various fields of science.