Nanopore Conductance

Electroosmotic flow Ioti conductance in nanochannels Ion transport in nanopores Nanopore conductance... 

Measured nanopore conductance graphs using a VLSI nanoclamp (light grey) and the commercial Axopatch 200B (dark line). 

As noted previously, the resistance of a conical-shaped nanopore is highly localized at the pore orifice. With that in mind, it is no surprise that the buildup of ions in the orifice leads to a higher overall conductivity of the nanopore, as experimentally measured by an increase in the current recording. In contrast, when a positive potential is applied, the flux of Cl" from the external solution to the pore interior is rejected by the pore orifice, depleting Cl within the pore and resulting in a decrease in the nanopore conductivity and measured current. This qualitative description of the effect of EDL is consistent with the nonlinear i V behavior shown in Figure 2.16. 

In contrast to this behavior at negative applied potentials, the particle-induced EDL effect and corresponding selectivity enhances the ion depletion at positive applied potentials, further decreasing the nanopore conductivity and the observed ionic current. Thus, a single resistive peak is always anticipated when a positive potential is applied across the nanopore. 

Another method of template-assisted synthesis, mainly used for the growth of metal nanowires, involves the deposition of metal into the cyUndrical pores or channels of an inert, non-conductive nanoporous electrode material. Track etch membranes, porous alumina, nanoporous conductive rubber polymers, metals, semiconductors, carbons and other solid materials have been used as templates to prepare nanometer-sized particles, fibrils, rods and tubules. The experimental set... 

Starrost F, Krasovskll E E, Schattke W, Jockel J, Simon U, Adelung R and Kipp L 2000 Cetineltes electronic, optical, and conduction properties of nanoporous chalcogenoantimonates Phys. Rev. B 61 15 697... 

One of the most important applications of nanoporous membranes is as nanoscaffolds in template synthesis, to replicate the structural features of the nanopores, or patterns, into metals [233], carbons [234], semiconductors [235,236], conductive polymers [237,238], and other materials [239]. The important characteristics of template synthesis have been best reviewed by Martin [188,240]. In short, it is a robust, general method suitable for the... 

Figure 3 Schematic of a nanoporous 2 film in the dark showing the movement of compensating positive ions (circles with + ) through the film that screens a negative potential (electrons shown as - ) applied to the Sn02 substrate electrode, (a) The electric field is screened close to the substrate when the potential is positive of the conduction band, but (b) extends further into the semiconductor for more negative potentials. The potential distribution also depends on the relative rates of interfacial versus interparticle charge transfer (Fig. 2).

There are multiple possible current pathways through a DSSC, as shown in Fig. 1, because the nanoporous cell consists of two interpenetrating, bicontinuous chemical phases. The relative conductivity of these two phases and of the connection between them, Rct, depends on the illumination intensity, applied potential, kinetics of the redox couple, and so forth. Therefore, the distribution of current pathways depends also on these variables. In the DSSC, the dark current will take the distributed path of least overall resistance (Sections III. A-III.C), meaning it will flow primarily through solution [50] under the expected conditions of Rct < / 2- The dark current is thus mainly a measure of reaction (5) in this potential range, even though reaction (4) is expected to be the dominant recombination... 

The incorporation of a cationic azobenzene derivative, p-( a> -dimethyl-ethanolammonioethoxyj-azobenzene bromide, into nanoporous silica films and the photochemical reactions of the adsorbed dye were investigated. The nanoporous silica films were prepared from tetramethoxysilane and octadecyltrimethyl-ammonium chloride by the rapid solvent evaporation method which we have reported previously. The adsorption of the cationic azo dye was conducted by casting an ethanol solution of the dye onto the nanoporous silica films. Upon UV light irradiation, trans-azobenzene isomerized photochemically to the c/s-form and photochemically formed c/ s-form turned back to the frans-form upon visible light irradiation. The nanoporous silica films were proved to be an excellent reaction media to immobilize organic photocromic species. 

The thin film of silica-surfactant mesostructured material was prepared by the reactions of TMOS and C18TAC, as reported previously[3]. The film was calcined in air to prepare nanoporous silica films. The adsorption of the dye onto the nanoporous silica film was conducted either by immersing the calcined film into an ethanol solution of the dye or casting the solution onto the film. 

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