Electron-hole pair coupling

For metallic environments, non-adiabatic effects in the form of electron-hole pair coupling is known to dominate the dissipative dy-namics. The bath of electron-hole pairs typically thermalizes within a few femtoseconds, which allows for a great simplification of the memoiy kernel. In view of the adsorbate dynamics, the bath thus remains in its equilibrium state and the memoiy kernel can be treated in the second-order Born-Markov approximation. For Markovian dynamics, the dissipative Liouvillian is often written in its diagonal Lindblad form " ... 

The latter contains all information about the STM eurrent and applied potential bias, as well as about the substrate density of states topology around the Fermi energy.These are important faetors influencing the strength of the electron-hole pair coupling induced by the STM tip, which determines uniquely the skewed thermal distribution appearing in eqn (29). As for Xe/Ni(110), a power law dependence of the transfer times... 

Regarding the emission properties, AM I/Cl calculations, performed on a cluster containing three stilbene molecules separated by 4 A, show that the main lattice deformations take place on the central unit in the lowest excited state. It is therefore reasonable to assume that the wavefunction of the relaxed electron-hole pair extends at most over three interacting chains. The results further demonstrate that the weak coupling calculated between the ground state and the lowest excited state evolves in a way veiy similar to that reported for cofacial dimers. 

However, others reached more ambiguous conclusions. Gates et al. developed a 2D model based on coupling NO vibration to surface phonons, but ignoring the possible role of electron-hole pairs, and successfully captured... 

Using this model they have tried to look at important chemical processes at metal surfaces to deduce the role of electronic nonadiabaticity. In particular, they have tried to evaluate the importance of electron-hole-pair excitation in scattering, sticking and surface mobility of CO on a Cu(100) surface.36,37 Those studies indicated that the magnitude of energy transferred by coupling to the electron bath was significantly less than that coupled to phonons. Thus the role of electron-hole-pair excitation in... 

Fig. 38. ID model of metal surface reconstruction. The coupling between discrete phonon modes (dashed line) and the electron-hole pair continuum (hatched) produces lattice instability.

The strength of the lattice instability near the Fermi vector depends on the magnitude of the electron-phonon coupling and on the phase space available for electron-hole pair excitation around 2kf. Thus, a reconstructive surface phase transition has to fulfill the following requirements in order to be ascribed to an electronically driven lattice instability ... 

In principle, the arrangement of reactive intermediates generated by electron - hole pair capture by two redox couples on the semiconductor surface may allow for divergent reaction paths when the same reactive intermediates are generated on the irradiated surface and in an isotropic environment. If a particular reactive intermediate is quite stable, the overall chemistry observed may be... 

Connection with vibrational lifetime on surfaces. The decay of molecular vibrations in the excitation of the electron-hole pairs of metallic surfaces have been identified with the mechanisms of vibration excitation by tunneling electrons [42]. Intuitively this may seem so. Indeed, an excited vibration may couple to the surface electronic excitations through the same electron-vibration matrix elements of Eqs. (2) and (4). The surface... 

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