Molecular eigenstates quantum yields

The state s is not really a physically accessible state, since in order to prepare the molecule initially in radiation with particular coherence between different frequencies which correspond to all the observed spectral lines from the molecular states which contain this zeroth order state initial state cj>0. The molecular eigenstates should then have unit quantum yields at very low pressure, a result which is not inconsistent with experimental extrapolations to zero pressure. This small molecule limit is depicted schematically in Fig. 4a. 

Chapter 6 deals with the time evolution of radiative decaying states of polyatomic molecules with special emphasis on radiative decay in internal conversion. The decay of a manifold of closely spaced coupled states is handled by the Green s function formalism, where the matrix elements are displayed in an energy representation that involves either the Born-Oppenheimer or the molecular eigenstate basis set. The features of radiationless transitions in large, medium-sized, and small molecules are elucidated, deriving general expressions for the radiative decay times and for the fluorescence quantum yields. 

The application of quantum-mechanical methods to the prediction of electronic structure has yielded much detailed information about atomic and molecular properties.13 Particularly in the past few years, the availability of high-speed computers with large storage capacities has made it possible to examine both atomic and molecular systems using an ab initio variational approach wherein no empirical parameters are employed.14 Variational calculations for molecules employ a Hamiltonian based on the nonrelativistic electrostatic nuclei-electron interaction and a wave function formed by antisymmetrizing a suitable many-electron function of spatial and spin coordinates. For most applications it is also necessary that the wave function represent a particular spin eigenstate and that it have appropriate geometric symmetry. 

Quantum-beat spectroscopy represents not only a beautiful demonstration of the fundamental principles of quantum mechanics, but this Doppler-free technique has also gained increasing importance in atomic and molecular spectroscopy. Whereas commonly used spectroscopy in the frequency domain yields information on the stationary states A ) of atoms and molecules, which are eigenstates of the total Hamiltonian... 

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