Stationary electron acceptor

The effect of alkali addition on the adsorption of NO on metal surfaces is of great importance due to the need of development of efficient catalysts for NO reduction in stationary and automotive exhaust systems. Similar to CO, NO always behaves as an electron acceptor in presence of alkalis. 

To observe a stationary current flow it is necessary to reoxidize the reduced dye molecule by an electron acceptor Ox ... 

Though there is fluid flow in the bulk of the electrolyte, it is found that there is a layer adjacent to the electrode in which the electrolyte is stationary, or stagnant. Thus the electron acceptors travel by convection from the bulk up to the stagnant layer and then cross the remaining boundary layer by diffusion. This transport by a convection-with-diffusion mechanism has not been taken into account so far. The equations for the time and space variation of concentration [i.e., Eq. (7.178)], for the transition time [Eq. (7.190)], and for the time variation of potential [Eq. (7.192)] have been derived for convection-free conditions, and they break down when convection becomes significant. The first approximation theory given above, therefore, deviates from experiment if the constant current is applied sufficiently long (times on the order of seconds) for convection to be important. 

Experimental measurements of photoemission currents are generally taken at far more positive potentials compared to the equilibrium potential of the electron electrode. Therefore, even when the solvated electrons are stable in the bulk of the solution, the electrode-emitter surface traps them effectively. For the electrode-to-solution transition of electrons to be irreversible (this is a necessary condition for measuring a stationary photocurrent), readily reducible substances — solvated electron acceptors (so-called scavengers) — are added to the solution. The electron level in a reduced acceptor (A ) is quite low, and this makes this state very stable trapping of electrons by a scavenger is the final transformation an emitted electron undergoes. 

Hi) n-electron acceptor/yc-electron donor stationary phases l-(3,5-Dinitrobenzamido)-l,2,3,4-tetrahydrophenanthrene W-(3,5-Dinitrobenzoyl)-l,2-diphenyl-1.2-diaminoethane yV-(3,5-Dinitrobenzoyl)-l,2-diaminocyclohexane yV-(3,5-DinitrobenzoyI)-(l-naphthyl)glycine amide Whelk-O 1 ULMO DACH DNB CHIREX 3005... 

The interaction between a solvated peptide or protein and a chemically modified RPC and HIC stationary phase in a fully or partially aqueous solvent environment can be discussed in terms of the interplay of weak physical forces. The main types of physical interactions that are involved in order of relevance and dominance for the establishment of the selective recognition and binding between a peptide or protein and RPC and HIC ligates are (I) hydrophobic interactions and related phenomena mediated by polarized electron donor or electron acceptor processes, (2) Lifshitz-London forces and van der Waals and associated weak dipolar interactions, (3) tt 7t and n ->dipole interactions, (4) hydrogen bond interactions, (5) electrostatic interactions, (6) metal ion coordination interactions, and (7) secondary macromolecular interactions involving force field effects. 

By analyzing the spectra of the low-temperature recombination luminescence of GaP crystals under conditions of stationary excitation, Tomas et al. [63] have determined the distances of electron tunneling. The spectra of this luminescence at 1.6 K consist of a large number of intensive narrow lines. The appearance of these lines is due to the fact that the energy of the quantum hv emitted as a result of electron tunneling between the charged donor and the acceptor depends on the distance, R, between the reagents... 

The exponential dependence of the efficiency of fluorescence quenching on the distance between a donor and an acceptor may be explained by the tunneling mechanism of electron transfer from a singlet-excited molecule of the donor to the acceptor. Indeed, in case of stationary excitation of donor particles, the value of J is determined by the stationary concentration n of the excited donor particles J = An where A is a constant. The value of n is, in its turn, inversely proportional to the rate constant, k, of deactivation of excited particles nft = nJexcexciting light, quantum yield of excited molecules, and n is the concentration of non-excited donor molecules. Thus, J = AnJexc4>lk. Hence, one can easily obtain... 

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