The Law of Force and the Size of Diatomic Molecules, as Determined by their Band Spectra

Abstract

IT is well known that from an evaluation of the vibrational energy of a diatomic molecule, as a function of the vibrational quantum number n, it is possible to deduce quantitatively the law of force of the molecule, in the vicinity of the equilibrium position of the two nuclei. Now when the dipole rotates, the nuclear separation r increases, and the amount of this increase depends upon the forces called into play when the nuclei are displaced from the equilibrium distance r_o. But these are the same forces which determine the frequency of vibration v_o and the vibrational energy. Hence, if neither the vibration nor the rotation is sufficiently violent to distort the electron orbits appreciably, there should be a direct connexion between the constants which enter into the vibrational energy function, and those which characterise the rotational energy.