Mobility thermally activated

Unusual magnetic and electrical properties might also arise from quasi one-dimensional crystal structures of these compounds. The acceptor stacks /especially TCNQ/ may be either regular, i, e. with equally spaced molecules, or alternating when composed of diads, triads or tetrads. In the latter case some substances exhibit EPR spectrum characteristic of mobile, thermally activated triplet states /triplet excitons/, The spectrum may result from the excitation of two or more coupled TCNQ entities /6, 7/. The triplet character of the paramagnetic excitation is shown by the anisotropic two-lines EPR spectrum which results from a zero field splitting of the triplet levels being described by the spin Hamiltonian /8/j... 

We Finally note that the MTR model is a priori more appropriate to disordered materials. It is not expected to give good results with single crystal OFET, especially when the mobility becomes temperature-independent (see Section 14.6.1.2). However, it has recently been invoked in the case of poly thiophene [112], the mobility of which is also thermally activated. 

Note The sodium acetate was added to the mobile phase solely to improve the separation. It had no detectable effect on the production of fluorescence during thermal activation, since the fluorescence reaction also occurred in the absence of sodium acetate. 

The last example for thermal activation to be discussed involves amino phases. Table 2.3 lists the publications concerning the specific detection of sugars and creatine derivatives by means of the fluorescence obtained on heating mobile phase-free amino layer chromatograms . 

The M2j pyrogram of a typical brown coal (Figure 1 (A)) reveals the significant thermally-activated molecular mobility which occurs on heating from room temperature to 600 K. This has been shown to be the result of fusion of the extractable component of such coals (9 ). The reduction in molecular mobility (increase in above... 

The high-volatile Liddell bituminous coal (Figure 2 (E)) shows little indication of thermally-activated molecular mobility below 500 K. There is some fusion between 500 and 600 K followed by a major fusion transition above 600 K which appears very similar to the high temperature transition of the Amberley coal. This Liddell coal, however, has only 6% liptinite, has a crucible swelling number of 6.5 and exhibits considerable Gieseler fluidity. We therefore attribute this high temperature fusion event to the aromatic-rich macerals of the coal and associate it with the thermoplastic phenomenon. This implies that a stage has been reached in the coalification processes at which aromatic-rich material becomes fusible. 

Figure 6. Compilation of step-mobilities derived from several experiments on Si(OOl) and Ge(OOl). The temperatures for the two data points for Ge(OOl) (filled triangles) have been scaled by the ratio of the cohesive energy of Si to Ge, 1.20. The dashed line shows a thermally activated process with an activation energy of 1.8 eV and a prefactor b kQ/k, 0 is the Debye temperature of Si, 650 K, and b = 0.38 nm.

It has been established from conductivity measurements that thermally activated and field-assisted hole hopping is responsible for the charge transport in solid polysilanes [48,49]. The mobility of the hole is as high as 10 m /V sec, while the mobility of the electron is a few orders of magnitude lower. In this section, we will show the reason why only the hole is mobile in polysilanes and how we can construct electron-conductive polysilanes. 

Annealing in metals can first lead to stress relaxation in which stored internal strain energy due to plastic deformation is relieved by thermally activated dislocation motion (see Figure 5.18). Because there is enhanced atomic mobility at elevated temperatures, dislocation density can decrease during the recovery process. At still higher temperatures, a process known as recrystallization is possible, in which a new set of... 

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