Chemistry, asked by garimaagnihotri5651, 1 year ago

How lambda max value helps in identifying molecular structure?

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Answered by Anonymous
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This term is used in UV-Visible spectroscopy where one looks at electronic transitions between the HOMO level and the LUMO level. Molecules absorb light over a range of wavelengths and when this absorbance is plotted as a function of wavelength one obtains an absorption spectrum. An absorption spectrum is simply a plot of absorbance vs wavelength. This plot gives us a range of wavelengths within which a molecule absorbs.

Lambda max refers to the wavelength in the absorption spectrum where the absorbance is maximum. Generally molecules absorb in a wavelength range centered around the lambda max. It acts as a single quantitative parameter to compare the absorption range of different molecules.

Sometimes spectral shifts occur due to changes in solvent polarity, changes in molecular structure etc. All such spectral shifts (i.e., blue shift or red shift) can be quantified with shift in lambda max. For example increase in conjugation length in a molecule shifts the lambda max to the red.

One can calculate lambda max for some conjugation systems such as conjugated dienes and polyenes using Woodward-Fieser rules (empirical rules) and this parameter can also be used in their structure determination.

MARK BRAINLIEST..

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