Chapter 11, Problem 11B.9P

Interpretation Introduction

Interpretation:

The rotational constant of the molecule has to be stated.  The value of $J$ for the most populated energy level at $\text{298}\text{K}$ and $\text{100}\text{K}$ has to be calculated.

Concept introduction:

A rotational spectrum is a spectrum in which only the rotation of molecule changes.  For a molecule to exhibit pure rotational spectrum, the molecule must possess a permanent electric dipole moment.  The molecules on rotation tend to experience a centrifugal force, this centrifugal force brings about a change in the molecular geometry and the moment of inertia of molecule.  This centrifugal distortion affects the energy relation to give the equation as shown below.

  $\tilde{F}\left(J\right)=\tilde{B}J(J+1)-{\tilde{D}}_J{J}^2{\left(J+1\right)}^2$.