Franck-Condon principle

The intensity of the lines is governed by the Franck-Condon principle.

The Franck-Condon principle is applied equally to absorption and to fluorescence.

Figure 7 illustrates the Franck-Condon principle applied to solvation.

The Franck-Condon principle and the Slater-Condon rules are named after him.

The Franck-Condon principle is a rule in spectroscopy and quantum chemistry that explains the intensity of vibronic transitions.

Bands can resolve into fine structure with spacings corresponding to vibrational modes of the molecular cation (see Franck-Condon principle).

The frequency gap Δ between the zero-phonon line and the peak of the phonon side band is determined by Franck-Condon principles.

Figure 1 illustrates the Franck-Condon principle for vibronic transitions in a molecule with Morse-like potential energy functions in both the ground and excited electronic states.

Under the latter, Condon rewrote his Ph.D. thesis using quantum mechanics, creating the Franck-Condon principle.

Franck-Condon principles can be applied when the interactions between the chromophore and the surrounding solvent molecules are different in the ground and in the excited electronic state.

The applicability of the Franck-Condon principle in both absorption and fluorescence, along with Kasha's rule leads to an approximate mirror symmetry shown in Figure 2.

In the original Franck-Condon principle, after the electronic transition, the molecules which end up in higher vibrational states immediately begin to relax to the lowest vibrational state.

The Franck-Condon principle has a well-established semiclassical interpretation based on the original contributions of James Franck [Franck 1926].

Just like in the Franck-Condon principle, the probability of transitions involving phonons is determined by the overlap of the phonon wavefunctions at the initial and final energy levels.

The transition between the ground and the excited state is based on the Franck-Condon principle, that the electronic transition is very fast compared with the motion in the lattice.

This separation of the electronic and vibrational wavefunctions is an expression of the Born-Oppenheimer approximation and is the fundamental assumption of the Franck-Condon principle.

The Franck-Condon principle is a statement on allowed vibrational transitions between two different electronic states; other quantum mechanical selection rules may lower the probability of a transition or prohibit it altogether.

Due to the Franck-Condon principle (atoms do not change position during light absorption), the excited state solvent shell is not in equilibrium with the excited state molecule ("solute").

For the Franck-Condon principle applied to phonon transitions, the label of the horizontal axis of Figure 1 is replaced in Figure 6 with the configurational coordinate for a normal mode.

This effect is analogous to the original Franck-Condon principle: the electronic transition is very fast compared with the motion of nuclei-the rearrangement of solvent molecules in the case of solvation-.

It should be clear that the quantum mechanical formulation of the Franck-Condon principle is the result of a series of approximations, principally the electrical dipole transition assumption and the Born-Oppenheimer approximation.

The Franck-Condon principle, in its canonical form, applies only to changes in the vibrational levels of a molecule in the course of a change in electronic levels by either absorption or emission of a photon.

In practice, such plots often give curves because of unaccounted anharmonicity in the potential; furthermore, the low population of the higher states (or the Franck-Condon principle) makes it difficult to experimentally obtain data at high values of .

The intensity of such transitions are explained by the Franck-Condon principle, which predicts that the most probable and intense transition corresponds to the vibrational excited state of the positive ion that has the same geometry as the neutral molecule.

The values of the rotational constants may differ appreciably because the bond length in the electronic excited state may be quite different from the bond length in the ground state, because of the operation of the Franck-Condon principle.