Introduction

Abstract

Optical spectroscopy is based on the Bohr-Einstein frequency relationship

$$\Delta E = {\text{ }}E_2 - {\text{ }}E_1 = h\nu \:.$$

((1))

This relationship links the discrete atomic or molecular energy states E_i with the frequency v of the electromagnetic radiation. The proportionality constant h is Planck’s constant (6.626× 10^-34 J s or 6.626× 10^-27 erg s). In spectroscopy, it is appropriate to use the wavenumber $\tilde v$ instead of frequency v. Equation (1) then takes the form:

$$\Delta {\text{E}}\;{\text{ = }}\;{\text{E}}_{\text{2}} - E_1 = hc\tilde v$$

where

$${\text{v}}\;{\text{ = }}\;{\text{c/}}\lambda \; = \;c\tilde v$$

((2))

.