Vibrational spectroscopy of diatomic molecules

Abstract

This chapter tackles the vibrational spectroscopy of diatomic molecules. It explains that one internal mode of motion of a diatomic molecule is its vibration, in which the internuclear separation increases and decreases periodically. Moreover, vibrational transition frequencies are used to determine the strengths and rigidities of bonds. The chapter notes how the vibrational spectrum of a diatomic molecule can be interpreted by using the harmonic oscillator model, with modifications that account for bond dissociation and the coupling of rotational and vibrational motion. It considers how the motion can become anharmonic in the sense that restoring force is no longer proportional to the displacement.