Photoconduction components

This confirms clearly, and quantifies explicitly, the picosecond photoconductivity component in (CH)x, which was already implied by the deconvolution procedure for evaluating the results of the single-gap measurements (see Figure 1.64). 

Poly Chlorinated Biphenyls. The photoconductivity detector provides good responses for polychlorinated biphenyls separated by GPC. The normal matrix components are detected by RI and UV detectors while the polychlorinated species show high responses in the electrochemical detector (Figure 8). ... 

Organic chemicals are used in electrophotographic processes as dyes, pigments, charge transport compounds, spectral sensitizers and components of the photoconducting medium. 

The photoconductivity of polysilanes was described in Section 5.8, and their electroluminescence is covered in Section 5.9.2. These properties make polysilanes possible components of polymer light-emitting diodes, either as charge transport layers or as the actual emissive materials.146 A drawback of the polysilanes is their photodegradation under ultraviolet irradiation, a problem which must be overcome if polysilanes are to become commercially useful. 

Abstract. It is shown, that the photoconductivity of Cgo single crystal essentially depends on a spin state of the intermediate electron-hole pairs. The distance between components of electron-hole pairs in states with uncorrelated spins and their lifetime were estimated as R>3.4 nm and r 10 9 s. 

Influence of EF on magnitude of photoconductivity of fullerene C6o single crystal in a weak MF can be explained in the following way. Increasing intensity of electric field causes the increase of radius of initial distance r0 between the components of electron-hole pairs and, consequently, the decrease of probability of geminate recombination. As a result, AI rises at small values of EF. At higher values of EF the probability of dissociation of pairs in states with uncorrelated spins increases, that causes nonlinear behavior of electrofield dependences of photoconductivity of fullerite C6o in MF. The distance between components of electron-hole pairs in states with uncorrelated spins was estimated as R>3.4 nm. 

Vinylcarbazole polymers and their CT complexes are widely known for their excellent photoconductive properties [115]. The CT processes in this polymer system have been extensively worked out by the conventional absorption spectroscopic techniques, but the application of the XPS technique to them has been rather limited [116]. For poly(Af-vinylcarbazole) (PVK)/perchlorate complex film synthesized via electrochemical polymerization and oxidation, it was shown that the NIs core-level spectrum exhibits a new high BE component shifted by about + 3.0 eV from the neutral carbazole nitrogen at about 400 eV. This new component was attributed to the positively charged carbazole nitrogen associated with CIO4 anion [117],... 

In the case of PVK, a charge transfer complex may be formed by the addition of a small amount of 2,4,7-trinitro-9-fluorenone (TNF). The PVK-TNF system has been studied widely in xerography and as a two-component material it is well understood [19]. It also has the additional advantage of a particularly low photoconductivity in the absence of light. Photoconduction due to the complex is efficient across the visible region of the spectrum, with the excited state exhibiting 80 % electron transfer from a carbazole unit of the PVK to an adjacent TNF unit. The dissociation of holes occurs in the two-component system by hole transfer to... 

Since it is important to address this issue at the earliest times following photoexcitation, measurements of transient photoconductivity in the picosecond to nanosecond regime were carried out [145,146,201,202], In response to an ultrafast light pulse (duration 25 ps), there is an initial fast photocurrent response with decay time of about 100 ps followed by a slower component with... 

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