Question

Qualitatively, how would the magnitude of the molar extinction coefficient compare in the infrared and the visible region? What is the physical factors determine any difference?

Answer 1

This formula is the common form of the Beer-Lambert Law, although it can be also written in terms of intensities:

A=log10(IoI)=ϵlc(1.6)A=log10⁡(Io/I)=ϵlc

The constant
ϵ is called molar absorptivity or molar extinction coefficient and is a measure of the probability of the electronic transition. On most of the diagrams you will come across, the absorbance ranges from 0 to 1

In UV region electronic transition occurs from one electronic state to another.but in infra red region vibrational transition from one vibrational state to another.

In visible region molar extinction coefficient is in nm

In IR region it is in cm-