Quantum relaxation processes initial state

In this section, we describe the motion of vibronic WPs created in a diatomic molecule that has only one vibrational mode. The influence of other degrees of motions such as rotation and nuclear spins are omitted for simplicity. Since our studies deal with the quantum property of the system in which relaxations can be neglected, the decoherence process is not taken into account in the following formulations. Assuming that the molecule occupies a single vibrational level v = 0 as an initial state, the WP generated by the absorption of a pump laser pulse is given as... 

Classical trajectories may either under- or overestimate the rate of IVR. Some relaxation processes are not allowed classically for example, quantum mechanical tunneling through potential energy barriers. Also, in the absence of such a barrier classical mechanics may still not allow an initial zero-order state to relax, even though the state is quantum-mechanically nonstationary. In the other extreme classical mechanics may be more chaotic than quantum dynamics. Quantum mechanics often gives more structured motion with more recurrences among zero-order states than does classical mechanics. Each of these extremes is illustrated in the following. 

Different photoreactions can be initiated in structurally related complexes of a metal ion as a result of the intrinsic properties of the LMCT excited state and radical-ion pairs. The excited-state reactions of azido complexes of Co(III) are one example of this chemical diversity.106-109 Irradiation of Co///(NH3)5N2+ aqueous acidic solutions in the spectral region 214 nm < 2exc < 330 nm produces Coin(NH3)4(H20)N, 6 0.6, and Co(aq)2 +, molar ratio.93 The ammonia photoaquation has two sources that also account for the large quantum yield of the photoprocess. One source competes with the formation of Co(aq)2 + from radical-ion pairs. These pairs must be produced with a quantum yield 0.5. The second source is a process unrelated to the Co(aq)2 + production and it has a quantum yield excited state where a Co-NH3 bond has been considerably elongated and where the electronic relaxation of the excited state has been coupled with aquation. A second rationale for the large aquation quantum yield is that a reactive LF excited state is populated by the LMCT excited state. 

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