Pictorial representation of delayed dissipation from the primary region to the secondary region over times and . Both ground and excited electronic -states undergo dissipation.
The model of (Ref. 12). Here is the frustrated translation displacement of present interest.
Energy levels and mechanism of photoexcitation in . The fast electronic de-excitation of the substrate transfers energy into the adsorbate and is followed by slow vibrational relaxation in the ground electronic state.
Upper panel: Real part of the TCF of vibrational displacements for at several temperatures. Lower panel: The imaginary part is shown only for , from Ref. 13.
(a): Population of state oscillating around its thermal value, and coherence shown as between states and , for coupled - and -regions and without a perturbing light pulse, vs time . The oscillations arise from the interaction of - and -regions, and the unperturbed populations and coherences , average around their Boltzmann distribution values and , . (b) Density matrix change , including delayed dissipation, found by adding the light pulse starting at . The three lower panels show changes for populations , and the top one the coherence change for pair . (c) Density matrix change , not including delayed dissipation, found by adding the light pulse starting at . The three lower panels show changes for populations , and the top one shows that now the quantum coherence of pair has disappeared.
Potential energy curves and electron transfer mechanism for a model system vs the perpendicular displacement of the cluster. The Si energy bands are included to show a fast electron transfer induced by light absorption, followed by slow vibrational relaxation steps in the dissipative processes.
(a) Spectral density function vs the phonon energy from our calculations of Si(111) driven by vibrations of the cluster. (b) Real part of the displacement TCF for Si(111) vs time at a temperature of (the imaginary part has a similar form).
Population of the excited electronic state, , for five vibrational levels, , following photoexcitation and electron transfer from to Si in our model with for the system, only with its fast delayed dissipation but no instantaneous electronic relaxation to the ground electronic state. The oscillations indicate quantum coherence induced by coupling to the medium. The model with gives the same population magnitudes with smaller oscillations over time.
Results for populations in our model, including the instantaneous electronic relaxation and the delayed vibrational relaxation (DD), for two electronic decay rates: (a) and (b) . Results also shown without the delayed dissipation (no DD) are similar and indicate that the overall relaxation of the electronically excited state is predominantly due to electronic dissipation.
Electronic states of the complex for excitation energies in the vicinity of , showing direct electron transfer. Here HO means the highest occupied MO and LU the lowest unoccupied MO.
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