Monolayers, interfaces

R. Blonder, E. Katz, Y. Cohen, N. Itzhak, A. Riklin, and I. Willner, Application of redox enzymes for probing the antigen—antibody association at monolayer interfaces development of amperometric immunosensor electrodes. Anal. Chem. 68, 3151—3157 (1996). 

Exp. No. Monolayer Interface Concentrat ion of Bulk Solution Degree of Compression vtl/Ao Relaxation Rate Constant aRT/A1 (sec-1) Corrected Relaxation Rate Constant aRT/AQ (sec-1)... 

Blackstock JJ, Donley CL, Stickle WF, Ohlberg DA, Yang JJ, Stewart DR, Williams RS (2008) Oxide and carbide formation at titanium/organic monolayer interfaces. J Am Chem Soc 130 4041 1047... 

The quasi-ideality of the (1 x l)Co/Cu(lll) and (1 x l)Co/Cu(110) monolayer interfaces allows a temperature dependent study of the polarisation dependent Debye Waller damping of the EXAFS oscillations i.e the analysis of the amplitude of the mean square relative displacements of the Co atoms parallel to the adsorbate layer, or perpendicular to it. The results are based on the analysis of data collected with the sample temperature T = 77 K and T = 300 K. The S—S and S—B (see above)... 

Jung DR, Czandema AW (1994) Chemical and physical interactions at metal/self-assembled organic monolayer interfaces. Crit Rev Solid State Mater Sci 19 1-54... 

Fig. 91. Schematics of the circular trough (not drawn to scale) used for the electrochemical generation of silver particulate films at monolayer interfaces...

Cadmium sulfide particulate films, generated in thicknesses of 300 50 A at arachidic acid (AA) monolayer interfaces, have been characterized in situ by STM under potentiostatic control [644], Electrical contact was made between the tip of the STM, acting as the working electrode (WE), which was in contact with the CdS particulate film floating on aqueous 0.30 M NaCl, and the reference (RE) and counter (CE) electrodes, placed in the subphase (Fig. 112) [644]. A well-defined single-reduction wave at about — 1.15 V was observed. Prolonged exposure to room light shifted the reduction peak to — 0.85 V. Electrical and photoelectrical characterizations have also been performed on Ti-foil-supported, 5000-A-thick CdS particulate films in an electrochemical cell (Fig. 113) [644]. The Ti foil was used as the WE, while the RE and CE were placed into 0.50 M... 

Epitaxial growth of PbS under well-compressed AA monolayers is explicable in terms of the geometrical complementarity between PbS and the AA head-groups. The strong intrinsic electrostatic interaction results in a very high Pb2+ concentration at the monolayer interface. The extremely low solubility of PbS in water (KSP = 8.81 x 10 29 at 25 °C) favors its rapid and random nucleation. However, the presence of the monolayer acts to drastically diminish the reaction... 

As stated in Sect. 6.4.1, it has been assumed that the measured experimental currents and converted charges when a potential Ep is applied can be considered as the sum of a pure faradaic contribution, given by Eqs. (6.130) and (6.131), and a non-faradaic one, /pnf and Qpnl. In order to evaluate the impact of these non-faradaic contributions on the total response, analytical expressions have been obtained. If it is assumed that initially the monolayer is at an open circuit potential, rest, and then a sequence of potential pulses , E2, -,Ep is applied, the expression for the non-faradaic charge Qp.nf can be deduced from the analogy between the solution-monolayer interface and an RC circuit [53] (shown in Fig. 6.24), so the following differential equation must be solved ... 

While the detection of the Si-H and Si-C modes indicates HREELS can probe the buried molecule/silicon interface, in general this method will be most sensitive to the terminal groups at the vacuum/monolayer interface. This is illustrated in Fig. 9 where spectra for several modified surfaces with different terminal functionalities are shown. In each case this terminal group is tethered to the surface via a Cio alkyl linker yet the spectra are significantly different. This is particularly evident in the spectra for the thienyl terminated surface in which the aromatic C-H stretch is clearly observed. In contrast this mode is quite small in the FTIR spectra, which are dominated by the contributions of the alkyl linker chain [51]. The observation of strong terminal group modes in the HREELS spectra indicates that these functional groups are likely present at the surface of the film and not buried back towards the H-terminated surface. This is consistent with their availability for sequential reactions as discussed in the previous section. 

Figure 3.9 illustrates the electrochemical and mass transport events that can occur at an electrode modified with a interfacial supramolecular assembly [9]. For monolayers in contact with a supporting electrolyte, the principal process is heterogeneous electron transfer across the electrode/monolayer interface. However, as discussed later in Chapter 5, thin films of polymers [10] represent an important class of interfacial supramolecular assembly (ISA) in which the properties of the redox center are affected by the physico-chemical properties of the polymer backbone. To address the properties of these thin films, mass transfer and reaction kinetics have to be considered. In this section, the properties of an ideally responding ISA are considered. 

Cyclic photoisomerization of the electron-acceptor between the trans- and cis-states permitted reversible piezoelectric transduction of the formation of the complexes with trans-A,A -bNA, and trans-3,3 -bN A at the monolayer interface, and their dissociation upon photoisomerization to czs-4,4 -bNA and c/s-3,3 -bNA. 

Figure 6.27. Schematic representation of a monolayer interface in a binary liquid A-B/external phase system according to the model of Li et al. (1989).

Blondeiv R., Katz, E., Cohen, Y., Itzhak, N., Riklin, A., and Willneg I. Application of redox enzymes for probing the antigen - antibody asseweiarion at monolayer interfaces Development of amperometric immunosensor electrodes. Ab[Pg.266]

Katz, E., and Willner, I. Amperometric amplification of antigen - antibody association at monolayer interfaces Design of immunosensor electrodes. J. Electroanal. Chem. 1996, 418,67-72. 

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