Electric multipolar induction in the far-infrared spectra of CO in liquid Ar: Translational/rotational contributions and static cancellation effects

Abstract

We have analyzed by means of molecular dynamics simulations the temperature and density dependence of the different pure induced components of the far-infrared integrated absorption coefficient of CO in liquid Ar (an interesting example for which experimental far-infrared spectra show the existence of high order electric multipolar induction). The main contribution to these components (for all the thermodynamic conditions we elected) comes from the rotation of the diatomic except for dipole induced-dipole absorption, where quantitatively rotation and translation are similar. By studying static cancellation effects separately in rotation and translation, we can assert an interesting result: All those contributions to the integrated absorption coefficient with radial decay equal or faster than the first repulsive decay of the solute–solvent interaction present enhancement effects and all those decaying slower present cancellation effects.