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What is UV VIS Spectroscopy?

Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. Ultraviolet-Visible (UV-VIS) Spectroscopy is an analytical method that can measure the analyte quantity depending on the amount of light received by the analyte.
Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV / Vis) in the ultraviolet-visible spectral field refers to absorption spectroscopy or reflectance spectroscopy. In the visible and neighbouring (near-UV and near-infrared (NIR)) ranges, this means that it uses light.

Ultraviolet Visible Spectrophotometer

Ultraviolet / Visible Area (UV-VIS) measurements span wavelengths from around 200 nm to 800 nm. The absorption by a molecule of ultraviolet or visible radiation results in transitions between the molecule’s electrical energy levels. The optical and electronic properties of different materials, such as films, powders, monolithic solids, and liquids, are suitable for characterization.
UV-vis spectroscopy is a cost-effective, simple, versatile, non-destructive, analytical technique suitable for a large spectrum of organic compounds and some inorganic species. As a function of wavelength, UV-vis spectrophotometers measure the absorption or transmission of light that passes through a medium.
In order to classify and measure the concentration of substances in liquid streams, high performance liquid chromatography and ultra-high performance liquid chromatography incorporate UV-vis detectors. It allows the detection of all animals by integrating these techniques with mass spectrometry.
UV VIS Spectroscopy Theory
When the interaction between incident radiation and the electron cloud in a chromophore results in an electronic transition involving the promotion of one or more of the outer shell or the bonding electrons from a ground state into a higher energy state, ultraviolet-visible ( UV-Vis) spectra are derived.
Generally, the UV and visible spectral bands of substances are large. And may not exhibit a high degree of compound recognition accuracy. Nonetheless, they are sufficient for quantitative assays and are useful as an alternate means of detection for several substances. The radiation from typical hot solids consists of several wavelengths and depends primarily on the temperature of the solid and is predictable from the principle of chance, the energy released at each given wavelength.
More recently, using a version of this-the tungsten-halogen lamp-has become standard practices. Radiation is transmitted deep into the UV zone through the quartz envelope. The most popular source is the deuterium lamp for the UV region itself, and a UV-Visible spectrometer would normally have all types of lamps to fill the whole wavelength spectrum.

Applications of UV VIS Spectroscopy

In research, ultraviolet / visible spectroscopy is used more commonly than in detection. Through first reacting the sample to bring the metal into solution as an ion, the trace metal content of an alloy, such as manganese in steel, can be determined.
A common technique for quantitative analysis of analytes in QA / QC, analytical research and government regulatory laboratories is UV-Visible spectrophotometry. The fundamentals of the approach are learned in school, such as Beer’s Law. UV-Visible Mid-range to Upper-end Spectrophotometers are typically used in research laboratories, including university and industrial laboratories.
The ion is then complexed or made to react so that it can be measured in a shape, such as manganese as the manganate(VII) ion. When the spectrum is registered, the absorbance is the most valuable bit of information since the concentration of the solution can be determined if the absorption coefficient of the chromophore is known, and thus the mass of the metal in the sample.

Principle of UV-Visible Spectroscopy

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.