Principle Of Uv-Vis Spectrometry:
In a classic absorption spectral measurement a monochromatic radiation is made to fall on a sample taken in appropriate container known as cuvette. In such a condition a part of the radiation is reflected, a part is absorbed, and an element is transmitted. The intensity of original radiation, Po is equivalent to the sum of the intensities of reflected (Pr), absorbed (Pa) and transmitted (Pt) radiation.
Po = Pr + Pa + Pt
The effect of reflection could be compensated through passing equivalent intensities of beams by the solution and through the solvent holed in the similar or similar container and comparing the transmitted radiations. We could then write the above equation as follows:
Po = Pa + Pt
The intensity of the transmitted light is measured and is found to depend on the thickness of the absorbing medium and the concentration, besides the intensity of the incident radiation. This dependence creates the basis of spectrometric determinations and is provided in terms of two fundamental laws. One is Bouguer's law or Lambert's law, that expresses the relationship among the light absorption capacity of the sample and the thickness of the absorbing medium; and the other is Beer's law, which expresses the relationship among the light absorptive capacity of the sample and its concentration. The two laws are combining together to provide Beer-Lambert's law.