Relaxation time carrier

Quantum well interface roughness Carrier or doping density Electron temperature Rotational relaxation times Viscosity Relative quantity Molecular weight Polymer conformation Radiative efficiency Surface damage Excited state lifetime Impurity or defect concentration... 

With the more conductive liquids, the ion concentration becomes so great that ion concentration fluctuations on a statistical basis are likely to be small. However, charging can take place by three other mechanisms (1) mechanical disruption of any double layer of ions that may exist at the surface in times that are short compared with the relaxation time, with a predominance of the surface ions going to the portion of fluid coming from the surface (2) unequal ion mobility with the larger ions unable to return to the bulk of liquid as readily as the smaller and more mobile ones and (3) contaminating materials, such as dust or surfactants at the interfaces serving as ion carriers into one portion or the other of the ruptured liquid. 

In the photolysis of. -dibromo-diphenyl-diazomethane in toluene the geminate pair effect is observed 87). However, it is accompanied by the enhanced emission by the escape product 7. This means that the carriers of the original polarization were the free radicals, whose lifetime is obviously shorter than the nuclear relaxation time. 

The localized-electron model or the ligand-field approach is essentially the same as the Heitler-London theory for the hydrogen molecule. The model assumes that a crystal is composed of an assembly of independent ions fixed at their lattice sites and that overlap of atomic orbitals is small. When interatomic interactions are weak, intraatomic exchange (Hund s rule splitting) and electron-phonon interactions favour the localized behaviour of electrons. This increases the relaxation time of a charge carrier from about 10 s in an ordinary metal to 10 s, which is the order of time required for a lattice vibration in a polar crystal. 

By lifetime we mean the average time that an excess carrier exists before annihilation by a carrier of the opposite sign. This is as opposed to relaxation time, the average time between collisions, or trapping time, the average time in a band before being trapped. We have used the same symbol, t, to represent both the lifetime and the relaxation time because this symbol... 

For positive lit electrodes one can register the drift of holes, and for negative ones- the drift of the electrons. The photosensitizer (for example Se) may be used for carrier photoinjection in the polymer materials if the polymer has poor photosensitivity itself. The analysis of the electrical pulse shape permits direct measurement of the effective drift mobility and photogeneration efficiency. The transit time is defined when the carriers reach the opposite electrode and the photocurrent becomes zero. The condition RC < tlr and tr > t,r should be obeyed for correct transit time measurement. Here R - the load resistance, Tr -dielectric relaxation time. Usually ttras 0, 1-100 ms, RC < 0.1 ms and rr > 1 s. Effective drift mobility may be calculated from Eq. (4). The quantum yield (photogenerated charge carriers per absorbed photon) may be obtained from the photocurrent pulse shape analysis. 

MHz, a it/2 pulse was 2.2 ysec and the data were acquired with the carrier frequency below resonance (the rhs of the spectrum in each figure). These spectra may be used to determine polymer crystallinity and to determine various kinds of macromole-cular motion. Also spin-lattice relaxation times in the rf interaction frame (Ti ) addition to conventional T- and T p relaxation times have been measured to help elucidate the various mechanisms responsible for the observed chemical shift line shapes. 

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