Free protons temperatures

Fig. 2 a, b. EPR and ENDOR spectrum of the low-spin Co(II) Schiff base complex Co(acacen) diluted into a Ni(acacen) 1/2 H20 single crystal, temperature 8K. a) EPR spectrum the two magnetically nonequivalent sites coincide for this particular orientation (EPR observer is marked by an arrow) b) ENDOR spectrum of H, 13C (enriched) and 14N ligand nuclei vp free proton frequency denote the AmN = 2 nitrogen ENDOR transitions. (From Ref. 12)... 

In thermal equilibrium, within a quantum statistical approach a mass action law can be derived, see [12], The densities of the different components are determined by the chemical potentials ftp and fin and temperature T. The densities of the free protons and neutrons as well as of the bound states follow in the non-relativistic case as... 

At elevated temperatures, where the electron lifetime was much shorter than the pulse lengths of a few nanoseconds used, a second mobile species could be observed as a slowly decaying after-pulse conductivity component for large pulses. This was attributed to proton conduction with a proton mobility of 6.4 x 10 cm /Vs in H,0 ice and a somewhat lower value in D2O ice. ° In the case of the proton, the mobility was found to have an apreciable negative activation energy of 0.22 eV. The motion and trapping of protons was tentatively explained in terms of an equilibrium between free protons and a proton complexed with an orientational L-defect. °... 

Figure 6.24 shows the temperature dependence of the frequency-derivative ENDOR spectra of an unstretched C-enriched c/s-rich sample. Spectra show a clear temperature dependence, where the structures of the lineshape become more prominent as the temperature is lowered. Some structures clearly show the feature of single resonance lines. The spectral lineshapes at higher temperahires are close to those reported in [116]. The detailed measurements of the frequencies of these signals have revealed that the frequencies of the structures are given by the multiple or fractional sum or difference of free proton and C nuclear Larmor frequencies, Vp and v., as marked in the figure. 

As previously mentioned, during flight, the air density changes significantly. The air pressure at 0 MSL (mean sea level) is approximately 1 bar, and at 10,000 m MSL, the air pressure is 260 mbar. Due to water-free proton transport in the HT-PEFC electrolyte, a constant conductivity of the membrane can be expected for low air densities. Figure 23.1a shows a lab test measurement of an HT-PEFC 70 cell stack (49 cm ) at varying ambient pressures from 1 bar to 660 mbar. The decrease in performance at low pressure is moderate compared to a low temperature PEFC, which experiences pronounced drying of the membrane, with an approximately... 

The chelation of metal ions was measured potentiometrically. A Radiometer pH meter, fitted with glass and calomel extension electrodes, was used for measuring the free proton concentration. The ionic strength was maintained constant at 13/by adding an adequate amount of potassium nitrate. During all titrations the temperature was maintained at 25 °C and a stream of C02-free nitrogen gas was passed through the titration flask. 

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