Self-localization, electronic states

The high electronic conductivity of the 7c-conjugated polymers (e.g. polypyrrole, polyacetylene) determined by the presence of delocalized electronic states, puts those polymers into the category of synthetic metals. The lower electronic conductivity of the redox and ion-exchange polymers, compared with the 7r-conjugated polymers, is due to the presence of localized electronic states. The redox polymers, which contain redox electroactive centres, conduct current by electron self-exchange... 

We used short broadband pump pulses (spectral width 200 cm 1, pulse duration 130 fs FWHM) to excite impulsively the section of the NH absorption spectrum which includes the ffec-exciton peak and the first three satellite peaks [4], The transient absorbance change signal shows pronounced oscillations that persist up to about 15ps and contain two distinct frequency components whose temperature dependence and frequencies match perfectly with two phonon bands in the non-resonant electronic Raman spectrum of ACN [3] (Fig. 2a, b). Therefore the oscillations are assigned to the excitation of phonon wavepackets in the ground state. The corresponding excitation process is only possible if the phonon modes are coupled to the NH mode. Self trapping theory says that these are the phonon modes, which induce the self localization. 

In the two-state approximation (TSA), ET kinetics for the DBA —> D" BA process may be modeled in terms of initial- ( ,) and final-state (T /) wave-functions, in which the transferring charge is localized primarily on the D and A sites, respectively. In the case of electrodes (e.g., metal or semiconductor), where multiple electronic states are involved, the D and A sites may still be taken to be localized and to involve atomic sites of the electrode near the site/or sites of attachment or contact with the bridge) SAM = self assembled monolayer STM = scanning tunneling microsccopy. 

For a state with occupation numbers rij, the one-particle self-consistent energies of interacting localized electrons are = s, + (6 / in the... 

PL quenching rate scales inversely with the QD diameter and can be understood in terms of a tunnelling of the electron (of the excited electron-hole pair) followed by a (self-) localization of the electron or formation of trap states. These observations are in line with the microscopic understanding of blinking phenomena of single QD. Our findings show also that single functionalized molecules can be considered as one of the probes for the complex interface physics and dynamics of colloidal semiconductor QD. 

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