Rotations and vibrations of polyatomic molecules

• cours magistral

Rotations and vibrations of polyatomic molecules When the potential energy surface V(~R1, ~R2, . . . , ~RN) is known we can com- pute the energy levels of the molecule. These levels can be an effect of: • Rotation of a molecule as a whole (end-over-end rotation) • Small vibrations around equilibrium configuration of the nuclei • Internal rotation - free or hindered • Tunneling • Large amplitude vibrations (van der Waals vibrations) Transitions between these levels are are observed in spectroscopy: • Infrared/Raman – vibrations • Terahertz (submillimeter) – rotations, large amplitude vibrations •Microwave –

• analytical formula for the rotational levels
• rotational energy
• vector of angular velocity
• rotational energies pattern for asymmetric rotors
• angular momentum of the rigid body
• rotations of polyatomic molecules
• electronic energy