what id the unit of relative intensity and is there any formula for finding relative intensity? what is the difference between the relative intensity and intensity ?

If one takes a IR spectra of a substance using a conventional instrument there are two choices for intensity. %Transmittance and Absorbance. %Transmittance is the % of the incident light (light emitted by the source) that reaches the detector after passing through the sample. The Aborbance =- log(%Tx100); where T = I/Io. Both of these are relative and not absolute because they are based on the amount of light emitted by the source (Io) and the amount received by the detector (I).
The untis km/mol is not an experimental quantity but is a computational on that is derived from the following integration based on Beer's law (Beer-Lambert):
A = 2.303|(integral sign)E(v) dv
Where A is absolute absorbance at a given frequency in kg/m, E(v) is the molar absorbtivity of the substance at freq v.
This unit allows the comparison of computationally determined absorbances with experimental ones.

Thank you for the reply. I am working on quantum chemical methods using Gauss view we are calculating intensity value. Is there any paper in which relative intensity calculated?

## All Answers (2)

Gloria Anderle· Fairleigh Dickinson UniversityThe untis km/mol is not an experimental quantity but is a computational on that is derived from the following integration based on Beer's law (Beer-Lambert):

A = 2.303|(integral sign)E(v) dv

Where A is absolute absorbance at a given frequency in kg/m, E(v) is the molar absorbtivity of the substance at freq v.

This unit allows the comparison of computationally determined absorbances with experimental ones.

For further information on the calculation see the open source article:

http://faculty.uccb.ns.ca/dkeefe/PDF/benzene%20liq%20gas%20I%20Bertie%20Keefe%20J%20Chem%20Phys%20101%204610%201994.pdf

Mahadevappa Naganathappa· GITAM UniversityCan you help by adding an answer?