Molecular Spectroscopy

The symmetry of molecules. Group theory: type of symmetry, irreducible representations and characters, and symmetry groups. Reduced representations and symmetry adapted molecular bases. Relation between molecular symmetry and degeneracy of energetic levels. Use of the integrand symmetry to detect null transition probabilities. The Born-Oppenheimer approximation and the molecular orbitals: linear combination of atomic orbitals and symmetry adapted linear combination of atomic orbitals.

Ro-vibrational (IR/Raman) spectroscopy: absorption, emission, and Raman processes. Molecular symmetry properties. Selection rules for rotarional and Raman spectroscopy. Harmonic oscillator and vibrational selection rules. Poliatomic molecules: normal modes, group theory, and molecular vibrations; anharmonic effects.

Vibro-electronic spectroscopic transitions (UV/Vis): the states of biatomic molecules and selection rules. Vibronic transitions and the Franck-Condon principle. Electronic spectra of poliatomic molecules: the importance of symmetry; vibro-electronic allowed and forbidden transitions; singlet-triplet transitions. Non-radiative decay, radiative decay (phosphorescence and fluorescence).

Molecules under external electric fields: electronic polarizability, Kuhn-Thomas sum rule, London forces, and the 1/R6 dependency. Nuclear magnetic resonance: shielding constant and diamagnetic and paramagnetic contribution. Spin couplings and hyperfine constants.