Electronic excitation, propagation

At the most fundamental level one follows the time development of the system in detail. The reactants are started in a specific initial (quantum) state and the equation of motion are propagated to give the final state. The equation of motion of the system is the time dependent Schroinger equation, or, if the atoms involved are heavy enough (not H or Li) Newtons equation. The starting point is the adiabatic potential energy surface on which the process takes place. For some reactions electronic excitations during the reaction are important and must be included in addition to the electronically adiabatic dynamics. 

These reactions would be followed by the above sequence (15), (16), and (17). The quantum yield of ozone disappearance would now be equal to six. It is known further (Table IV) that, at wavelengths above 5900 A., only the ground state 0(3P) atom is formed in the photolysis of ozone and the reaction (17) is incapable of propagating a chain. Thus, it is to be expected that the ozone quantum yield should be 2 at wavelengths > 5900 A. This has now been confirmed experimentally.44 There does not appear to have been any study of the vacuum ultraviolet photolysis of ozone but it should be apparent from the foregoing discussion that reactions of electronically excited O and 02 are involved. 

In photoelectron diffraction experiments monoenergetic photons excite electrons from a particular atomic core level. Angular momentum is conserved, so the emitted electron wave-function is a spherical wave centered on the source atom, with angular momentum components / 1, where / is the angular momentum of the core level. If the incident photon beam is polarized, the orientation of the emitted electron wave-function can be controlled. These electrons then propagate through the surface and are detected and analyzed as in LEED experiments. A synchrotron x-ray source normally produces the intense beams of variable energy polarized photons needed for photoelectron diffraction. 

The first step in photoemission (and some other techniques) involves photon propagation through the surface region to the location of the electron excitation. 

When a femtosecond laser pulse passes through nearly any medium, coherent vibrational excitation (in general, initiation of coherent wavepacket propagation) is likely [33, 34]. One- or two-photon absorption of a visible or ultraviolet pulse into an electronic excited state can result in phase-coherent motion in the excited-state potential [35]. Impulsive stimulated Raman scattering can initiate phase-coherent vibrational motion in the electronic... 

It is well known that electron correlation plays a key role in understanding the most interesting phenomena in molecules. It has been the focal point of atomic and molecular theory for many years [1] and various correlated methods have been developed [2]. Among them are many-body perturbation theory [3] (MBPT) and its infinite-order generalization, coupled cluster (CC) theory [4,5], which provides a systematic way to obtain the essential effects of correlation. Propagator [6-9] or Green s function methods (GFM) [10-14] provide another correlated tool to calculate the electron correlation corrections to ionization potentials (IPs), electron affinites (EAs), and electronic excitations. 

A Model of Localization, Soliton Propagation, and Self-Trapping in an Electronically Excited Atomic Lattice. 

The initial dynamics of hydrogen transfer on this potential energy surface are determined by the propagation of the vibrational wavepacket created upon electronic excitation. 

As is known, crystals are defined as molecular when the interaction between different molecules is much smaller than the interaction between atoms and electrons within the molecule. In consequence, the molecules in such crystals preserve some individual properties. Therefore, in the zeroth approximation, the lowest electronic excited state of the crystal can be considered as a state in which one molecule is excited, and the others in their ground state. As a consequence of the translational symmetry and of the intermolecular interaction, the localization of the excited molecule is not stable, and the excitation energy will be transferred from one molecule to another, propagating like a wave through the crystal.2... 

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