Transition moment electric dipole

Equation (A3.13.17) is a simple, usefiil fomuila relating the integrated cross section and the electric dipole transition moment as dimensionless quantities, in the electric dipole approximation [10, 100] ... 

Let us enquire about the electric dipole transition moment between two d orbitals as expressed in Eq. (4.7). 

In collaboration with E.L. Sibert, we have learned to interpret these Franck-Con-don forbidden, pure torsional band intensities in S,-S0 absorption spectra quantitatively and thus place the key ml+ assignment on firm ground.27 The forbidden bands follow the selection rule Am = 3, so we need a perturbation of the form Vel cos 3a. Working in an adiabatic representation with the S0 and S, electronic states denoted by y0(g a) and /,( a) and the torsional states by m" and m, the electric dipole transition moment is,... 

Vibrational circular dichroism arises from the interference of the electric dipole transition moment (p joi and the magnetic dipole transition moment (m )io and is proportional to the rotational strength, / ,o, where... 

The spectra in this figure represent one of the strongest cases for the ring current mechanism of VCD intensity enhancement. In this case, currents increase the magnetic dipole transition moment without altering the relative arrangement of electric dipole transition moments and the relative intensity pattern is preserved. In the structures 42 and 43, we show that in the A complex, 42,... 

We now consider the electric-dipole selection rules for radiative transitions between energy levels of the same electronic state of a polyatomic molecule. The electric-dipole transition moment is (4.91), which becomes... 

FIGURE 16. The exciton chirality rule relates the torsion angle or helicity of two electric dipole transition moments (<--->) to the signed order of the CD Cotton effects... 

With infrared reflection absorption spectroscopy (IRRAS), it is possible to obtain information about the orientation of enzyme molecules adsorbed on flat metal surfaces (3,4). Electric dipole-transition moments oriented perpendicular to a flat metal surface show enhanced IR absorbance. IR bands due to vibrations of groups with transition moments oriented parallel to the surface are not observed. The IR-beam component which is polarized perpendicular to the plane of incidence (parallel to the surface) contains no information and can be eliminated by using a polarizer. 

For six modes, corresponding to translational and rotational motions, kt and vt, are zero. Within the harmonic approximation (HA), electric dipole transition moments are... 

Although exciton coupling leads to shifted and broadened, if not split, UV-visible spectra of the composite molecule, when the chromophores are held in a chiral orientation, exciton coupling can be detected even more clearly in the CD spectrum as two oppositely-signed CE s typically corresponding to the relevant UV-visible absorption band(s). The signed order of the CD transitions correlates with the relative orientation of the relevant electric dipole transition moments, one from each chromophore, and hence the absolute configuration of the composite molecule (Exciton Chirality Rule.)[2] For the bis-anthra-... 

Figure 27. UV spectra of anthracene and the ring fused bis-anthracene (ref. 2). On the anthracene structure are shown the in-plane orientations of the electric dipole transition moment vectors associated with the intense short wavelength UV bands (1Bb) near 250 nm and the weak long wavelength bands ( LJ near 360 nm. The Xmax for the exciton bands of bis-anthracene are red shifted from the corresponding bands in the parent, as the vectors intersect at >90°.

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