Introduction: Survery of spectra of diatomic molecules, the hydrogen molecule ion, its double-well potential and important conclusions.

The Ro-vibrator model: Wave function and energy states of rigid rotator, harmonic oscillator, selection rules for transition, state population, anharmonicity of diatomic molecules, rotating vibrator, its spectra and selection rules for transition, intensity distribution, spectra of course and fine structure, the symmetric top model, isotopic spectra and determination of molecular constants.

Electronic spectra of diatomic molecules: Energy levels, symmetry of electronic and ro-vibronic states, electric dipole selection rules, Franck-Condon principle, coupling of angular momenta (Hund's coupling cases), transition between electronic states, energy-level diagram of sigma-sigma and pi -pi transition.

Comparative study of Potential Energy Functions: Comparative study of Morse, Hulburt-Hirschfelder, Rydberg, Rosen-Morse, Manning-Rosen-Newing, Poschl-Teller, Hylleraas, Kratzer, Davidson, Mecke-Sutherland, Linnett, Lippencott, Frost-Mosulin and Rafi and Fayyaz potential functions for diatomic molecules.

Term Manifold of Electronic States: Unites and separated atoms approach, molecular terms from electronic configuration.

Raman Spectra: Classical theory, induced polarization and polarizability, quantum theory of rotation and vibration Raman effects.

Recommended Text:
1. C. C. Gerry, P. L. Knight, “Introductory Quantum Optics”, Cambridge (2005).
2. G. Herzberg, “Spectra of Diatomic Molecules”, Van Nostrand, 1965.
3. B. H. Bransden, C. J. Joachain, “Physics of Atoms and Molecules”, 2nd ed. Pearson Education (2003).
4. K. V. Raman, R. Gopalom, P. S. Raghavan, “Molecular spectroscopy”, Thomson Singapore (2004).
5. S. Svanberg, “Atomic and Molecular Spectroscopy”, 4th Ed. Springer Verlag, (2001).