Resonance excited state

Next we model the laser-driven electron dynamics quantum mechanically to reveal analogies and differences to the simple classical model. In view of the SPODS mechanism, which is based on resonant interactions, we consider only two quantum states at hrst, the ground state and the resonantly excited state. Eor this purpose, we briehy recapitulate the relevant equations for a two-state system driven on... 

There can be a difference between the dissociation of polyatomic molecules and delayed ionization in the nature of the initial excitation. In ZEKE spectroscopy the state that is optically accessed (typically via an intermediate resonantly excited state) is a high Rydberg state, that is a state where most of the available energy is electronic excitation. Such a state is typically directly coupled to the continuum and can promptly ionize, unlike the typical preparation process in a unimolecular dissociation where the state initially accessed does not have much of its energy already along the reaction coordinate. It is quite possible however to observe delayed ionization in molecules that have acquired their energy by other means so that the difference, while certainly important is not one of principle. 

Here Me is the pure electronic transition moment for the resonant excited state e, of which v is a vibrational level of band width Tv, vvi is the transition frequency from the ground state vibrational level (0 to the excited vibrational level (v). The /1-term becomes larger as the denominator becomes smaller (resonance condition) and as Me becomes larger (stronger electronic absorption). The numerator contains the product of two overlap integrals of vibrational wavefunctions (Franck-Condon overlap) involving the /, j and v states. Because of the orthogonality of vibrational wavefunctions (Section 1.2),... 

CI0H HOOP wag and the 922 cm-1 line to an HCn-Cl2H HOOP mode. The line at 854 cm-1 was attributed to the CI4H HOOP. As the intensities of the lines depend on the resonant excited state geometry, the enhancement of the 922 cm-1 line in bathorhodopsin indicates that the twist around the 11,12 bond is different in the excited state from that of the ground state, i.e., a situation expected to occur in cis-trans isomerization. Thus the resonance Raman data showed that the chromophore configuration in bathorhodopsin is a perturbed all-trans. 

Considerable energy is readily stored in the lowest np resonance excited states... 

Here, e and e represent slow and fast electrons, respectively, and the superelastic collision may preferentially produce the A resonant excited state because A — A is a strong dipole transition. (Note that inelastic cross sections for electron-atom collisions are generally larger for dipole-allowed transitions compared to dipole-forbidden transitions.) Since the ground state density N is high, the electron excitation of A following Eq. (7) is fast ... 

When the angular frequency of the exciting light (cuo) becomes elose to the transition angular frequency for an absorption band of the molecule (u ) the first term of Eq. (6.1-1) begins to dominate, and the resonant excited state dominates the sum over states of the Raman polarizability expression. Thus, for excitation into an absorption band (loq w LOri) Eq.(6.1-1) may now be rewritten as... 

B-term resonance Excited state is vibronically coupled to other excited states vibronically active modes are enhaneed. 

Pt -X bond lengths on excitation of the complex from the ground to the resonant excited state in each case. There is, however, some difficulty in calculating this shift from the theory oiMingardi and Siebrand (96) owing to our lack of knowledge as to the origins of the mixed-valence transitions. 

For resonant processes, resonant excited states must be added to the diagrams in Fig. 4 by use of solid horizontal lines. When any of the arrow heads in the diagrams touches a solid horizontal line, the corresponding electrical susceptibility term may contain the resonant energy denominators and display resonance enhancement as the resonance condition is approached. For example, if there is an excited state such that mg 3 the diagram in Fig. 4(Cj) becomes resonant with the energy denominator The diagram in Fig. 4(c2), however, remains... 

After separation, the polarizability in Equation (9.22) is the sum of four terms (i) the A-term, also known as the Condon approximation, is a result of the pure electronic transition moment and vibrational overlap integrals (ii) the B-term results from vibronic coupling of the resonant excited state with other excited states (iii) the C-term has to do with the vibronic coupling of the ground state with one or more excited states and (iv) the D-term results from vibronic coupling of the resonant excited state to other excited states coupling in both the electronic transition moments. 

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