Quantum mechanics; Time-dependent and time-independent Schrödinger equation; Selection rules; Stationary states; Time-dependent perturbation theory; Heisenberg uncertainty principle; Fourier transformations; Quantum dynamics; Time-resolved spectroscopy; Light scattering; Raman spectroscopy; Absorption; Spontaneous emission; Stimulated emission; Born–Oppenheimer approximation; Group theory; Character tables; Reducible and irreducible representations; Normal modes; Electronic configurations and states; Lineshapes; Line broadening; Radiationless transitions; Molecular symmetry; Coherent excitation; Classical mechanics