Polarization time

Oxidized regions are uniform in composition and consequently in charge density at every polarization time. Regions of neutral polymer have, as well, a uniform composition. Both oxidized and neutral regions have an amorphous structure. 

This indicates a constant expansion rate for each cylinder during the polarization time. The expansion rate decreases with increasing cathodic potential of prepolarization, decreasing anodic potentials, or decreasing step temperatures, which is in good agreement with experimental results, as will be shown later. 

The relaxation charge consumed is obtained by integration along the polarization time ... 

These two equations quantify the evolution of the relaxation current and the relaxation charge as a function of the polarization time when the conducting polymer is submitted to a potential step from Ec to E. They are the relaxation chronoamperogram and the relaxation chronocoulogram,... 

These are the simplest expressions for the evolution of the relaxation current, the relaxation charge, and the oxidized area during the polarization time. 

The concentration of the remaining oxidation centered on the relaxed film at any oxidation time is defined by the difference between the density of charge stored in the point at which the film attains an oxidation steady state at the working potential and large polarization times and the charge density stored after a given polarization time [< j(0]-So the diffusion flow of ions is given by... 

Decay transients, photo electrodes and, 505 Degradation rate as a function of polarization time, 328 Degradation reactions simultaneous with electrode polymerization, 326 DeLevie on the density of broken bonds and the effect on the potential of zero charge, 75... 

CO adsorption on electrochemically facetted (Clavilier), 135 Hamm etal, 134 surfaces (Hamm etal), 134 Platinum group metals in aqueous solutions, 132 and Frumkin s work on the potential of zero charge thereon, 129 Iwasita and Xia, 133 and non-aqueous solutions, 137 potentials of zero charge, 132, 137 preparation of platinum single crystals (Iwasita and Xia), 133 Platinum-DMSO interfaces, double layer structure, 141 Polarization time, 328 Polarons, 310... 

FIGURE 14.10 Polarization-time relation during the formation of a new phase. 

The size of the deposit depends on the size of the hole and not on polarization time, denoting a certain balance between electrochemical energy and the surface energy of the cluster. This technique has been also employed to study the filling of Au cavities by Bi and Ag. In the latter work, the behavior of Bi is contrasted with that of Ag. While the holes are filled at underpotentials in the first... 

As we shall see, all relaxation rates are expressed as linear combinations of spectral densities. We shall retain the two relaxation mechanisms which are involved in the present study the dipolar interaction and the so-called chemical shift anisotropy (csa) which can be important for carbon-13 relaxation. We shall disregard all other mechanisms because it is very likely that they will not affect carbon-13 relaxation. Let us denote by 1 the inverse of Tt. Rt governs the recovery of the longitudinal component of polarization, Iz, and, of course, the usual nuclear magnetization which is simply the nuclear polarization times the gyromagnetic constant A. The relevant evolution equation is one of the famous Bloch equations,1 valid, in principle, for a single spin but which, in many cases, can be used as a first approximation. 

Figure 2, Cross-polarization timing diagram ( see text for discussion), (Reproduced with permission from Ref, 40, Copyright 1982, Royal Society of London,)...

FIGURE 3.5 (a) Impedance and (b) polarization behavior of a freshly prepared La072Sr018MnO3 electrode for 02 reduction as a function of cathodic polarization time at 200 mAcm 2 and 900°C in air. The impedance was measured at open circuit and the numbers are frequencies in hertz. (From Jiang, S.P. and Love, J.G., Solid State Ionics, 138 183-190, 2001. With permission.)... 

NMR in dichloromethane-d1. The spectrum was run quantitatively with broad band heteronuclear decoupling, b) 1JC CPMAS NMR of uncured PTEB. Cross-polarization time was 4.5ms the rotor speed was 2.3 kHz the cross polarization field was 50 kHz. Chemical shifts are relative to TMS. 

NMR relaxation measurements such as cross-polarization time constants (7ch) can also yield useful information regarding alkyl-chain mobility. Sindorf and Maciel [159] have characterized the relative mobility of low-density Cg and Cig stationary phases ( 2.6 and 1.7 p,mol/m, respectively) as a function of carbon position from the... 

Figure 4. The influence of magic angle spinning on the SL cross polarization time constant. In the PlP-cured epoxy the time constant for the nonprotonated carbons increases by about 50% for = 1-3 kHz while those of the protonated carbons are virtually unchanged over this range.

Figure 5. The rf pulse sequences for determining SL cross polarization time constant Ten, C-13 T,p and C-13 Tj under proton decoupling. Each experiment starts with a SL cross polarization.

The initial building-up of the carbon magnetization via polarization transfer is characterized with the spin-lock cross-polarization time Tcir It is sensitive to the static interactions, i.e. transfer of the polarization via static dipolar interactions (proportional to e J). Hence, the shortest TCH will have carbons a) in more rigid systems and b) with more directly attached protons, particularly the CH2 (or... 

Fig. 6. Cross-polarization timing diagram for the H-I3C spin system. Upper part, the H channel lower part, the 13C channel.

The first measurements of Na nd fine structure intervals using quantum beats were the measurements of Haroche et al41 in which they detected the polarized time resolved nd-3p fluorescence subsequent to polarized laser excitation for n=9 and 10. Specifically, they excited Na atoms in a glass cell with two counterpropa-gating dye laser beams tuned to the 3s1/2—> 3p3/2 and 3p3/2— ndj transitions. The two laser beams had orthogonal linear polarization vectors et and e2 as shown in Fig. 16.9. 

Io is the maximum intensity, TCp is the cross polarization time constant and Tiph and TlpC are the relaxation times for ll and 13C in the rotating frame. The cross polarization rate (l/TCp) depends on the square of the dipolar interaction while the relaxation time in the rotating frame provides... 

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