Ultraviolet-Visible Spectroscopy Essay

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Ultraviolet-visible spectroscopy is defined as the measurement of the attenuation of a beam of light after it pass through the sample or after reflection from a sample.Single wavelength or over an extended range can be the absorption measurement of UV spectroscopy . The ultraviolet region falls in the range between 190-380 nm, the visible region fall between 380-750 nm.(1)
Principle
Origin of UV-visible spectra
When the matter interacts with radiation ,various process such as absorbance, fluorescence/phosphorescence ,reflection, scattering, and photochemical reaction can be occur.The measuring of UV-visible spectra is only depend the absorbance due to absorption of light by matter can increase the energy level of molecule.. The sum of the molecule’s
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c) Hyperchromic effect It is an effect which shows the absorption maximum increases. Generally, introduction of an auxochrome in the compound will lead to hyperchromic effect.

d) Hypochromic effect Hyperchromic effect is opposite to hyperchromatic effect which result in the decreasing of intensity of absorption maximum. This is due to the distortion of the geometry of the molecule with an introduction of new group.(1)
ABSORBANCE LAWS
(i) BEER’S LAW
This law states that the intensity of a beam of monochromatic light decrease exponentially with the increase in concentration of the absorbing substance.
- dI/ dc ᾱ I I= Io. eˉkc
(ii) LAMBERT’S LAW
It states that the rate of decrease of intensity with the thickness of medium is directly proportional to the intensity of the light when a beam of light is allowed to pass through a transparent medium.Its limitation is that it can only describing the behavior absorption of dilute

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