The Principle of UV-Visible Spectroscopy is based on the absorption of ultraviolet light or visible light by chemical compounds, which results in the production of distinct spectra. Spectroscopy is based on the interaction between light and matter. When the matter absorbs the light, it undergoes excitation and de-excitation, resulting in the production of a spectrum.
When matter absorbs ultraviolet radiation, the electrons present in it undergo excitation. This causes them to jump from a ground state (an energy state with a relatively small amount of energy associated with it) to an excited state (an energy state with a relatively large amount of energy associated with it). It is important to note that the difference in the energies of the ground state and the excited state of the electron is always equal to the amount of ultraviolet radiation or visible radiation absorbed by it.
UV-Visible Spectroscopy and the Beer-Lambert Law
The statement of the Beer-Lambert law can be written as follows: When a beam of monochromatic light is made incident on a solution that contains a substance that absorbs the monochromatic light, the rate at which the intensity of the beam decreases along the thickness of the solution is directly proportional to the concentration of the absorbing substance in the solution and is also directly proportional to the intensity of the incident monochromatic radiation.
As per the Beer-Lambert law, the greater the number of absorbing molecules (that have the ability to absorb light of a specific wavelength), the greater the extent of absorption of the radiation.
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Frequently Asked Questions on Principle of UV Visible Spectroscopy
What are the Applications of UV-Visible Spectroscopy?
UV-Visible spectroscopy is widely used in the field of analytical chemistry, especially during the quantitative analysis of a specific analyte. For example, the quantitative analysis of transition metal ions can be achieved with the help of UV-Visible spectroscopy. Furthermore, the quantitative analysis of conjugated organic compounds can also be done with the help of UV-Visible spectroscopy. It can also be noted that this type of spectroscopy can also be carried out on solid and gaseous analytes in some conditions.
What kinds of detectors are used in UV-Visible spectroscopy?
A widely used detector in UV-Vis spectroscopy is the Photomultiplier tube. It consists of a photoemissive cathode (which is a cathode that releases electrons when it is hit by radiation photons), multiple dynodes (which is a device that emit multiple electrons for each striking electron), and an anode.
What is UV-Visible spectroscopy?
Ultraviolet and visible (often abbreviated to UV-Vis) absorption spectroscopy is a type of spectroscopy which involved the calculation of a light beam’s attenuation (strength/intensity weakening) after it passes through a sample or reflects from a sample surface