Transition dipole coupling

Figure 3.15 Variation in the population transfer to 1310000) and 302000) with 1013000) as branch state as a function of detuning from the branch state. All 21 states and dieir transition dipole couplings have been included in the calculations. (From Ref. 61).

Torii H, Tasumi M. Local order and transition dipole coupling in liquid methanol and acetone as the origin of the Raman noncoincidence effect. J Chem Phys 1993 99 8459-8465. 

Torii H, Tasumi M. Raman noncoincidence effect and intermolecular interactions in liquid dimethyl sulfoxide simulations based on the transition dipole coupling mechanism and liquid structures derived by Monte Carlo method. Bull Chem Soc Jpn 1995 68 128-134. 

Keiderling TA, Kubelka J, Hilario J (2006) Contribution of transition dipole coupling to amide coupling in IR spectra of peptide secondary structures. Vibrational Spectroscopy of Biological and Polymer Materials 253-324... 

Ordinary STIRAP is only sensitive to the energy levels and the magnitudes of transition-dipole coupling matrix elements between them. These quantities are identical for enantiomers. Its insensitivity to the phase of the transition-dipole matrix elements renders STIRAP incapable of selecting between enantiomers. Recently we have demonstrated [11] that precisely the lack of inversion center, which characterizes chiral molecules, allows us to combine the weak-field one-and two-photon interference control method [29,54,95,96] with, the strong-field STIRAP to render a phase-sensitive AP method. In this method, which we termed cyclic population transfer (CPT), one forms a STIRAP loop by supplementing the usual STIRAP 1) o 2) <=> 3) two-photon process by a one-photon process 1) <=> 3). The lack of inversion center is essentrat, because one-photon and two-photon processes cannot connect the same states in the presence of an inversion center, where all states have a well defined parity, because a one-photon absorption (or emission) between states 1) and 3) requires that these states have opposite parities, whereas a two-photon process requires that these states have the same parity. 

In analyzing the vibrational spectra of polypeptides, it is important to include certain intermolecular contributions to Vinter- We discuss here three of these contributions, two of which, hydrogen bonding and transition dipole coupling, have played a very important role in the development of our force field. 

A resonance interaction can occur between two oscillators when one of them is in an excited state. The energy of this interaction is determined by that part of the total Hamiltonian that represents all pairwise coulom-bic interactions between electrons and nuclei in the two groups. At sufficiently large distances (probably over 3 A) these interactions can be expanded in a multipole series, of which the first important term for a neutral system is that due to transition dipole coupling (TDC). Higher transition multipoles may be important in some cases (Cheam and Krimm, 1985), but we treat here only the TDC case (Krimm and Abe, 1972 Moore and Krimm, 1975 Cheam and Krimm, 1984c). 

Fig. 4. Geometrical parameters in transition dipole coupling interaction.

Calculated Amide I, II, and HI Frequencies with Transition Dipole Coupling Included for Types I, IV, and HV p Turns... 

Calculated value of maximum splitting of amide I modes, with and without transition dipole coupling. 

DNA has also been applied for synkineses of molecular wires. One example applies aligned DNA fibers in which one acridine orange molecule intercalates per 10 base pairs. It shows photocurrents if a voltage is applied to the material placed between comb-form electrodes (Okahata et al., 1998). The dye-DNA complexes are probably not useful as parts of a charge separation system, but they clearly demonstrate extensive electronic communication between bound drug molecules—an influence that serves to raise the efficiency of transition dipole coupling at long distances. 

Transition dipole moment interactions between peptide groups can influence higher frequency modes, as was shown by their effects on the splittings of amide I and amide II modes of a-helix and 5-sheet polypeptides [15, 16]. Such transition dipole coupling (TDC) arises from the potential energy of interaction, between transition moments, Ap, in different peptide groups, and is given by [17]... 

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