Spectroscopic investigation of spin zero homonuclear and heteronuclear molecules

In the present article, we introduce a model to investigate the energy spectrum of a relativistic rotor by considering the Klein-Gordon Hamiltonian. Rotational spectral lines are a signature of homonuclear and heteronuclear systems and play a key role in understanding diatomic molecules. We show that the energy-correction term arising due to unequal masses influences the line separation. Determining the rotational constant enables one to calculate the moment of inertia and bond length of the molecule.