Langmuir alternate layers

Y.D. Jin, Y. Shao, and S.J. Dong, Direct electrochemistry and surface plasmon resonance characterization of alternate layer-by-layer self-assembled DNA-myoglobin thin films on chemically modified gold surfaces. Langmuir 19, 4771—4777 (2003). 

Y. Lvov, B. Munge, O. Giraldo, I. Ichinose, S.L. Suib, and J.F. Rusling, Films of manganese oxide nanoparticles with polycations or myoglobin from alternate-layer adsorption. Langmuir 16, 8850-8857 (2000). 

Luminescent multilayer systems have been reported extensively in Langmuir-Blodgett studies however, reports of intrinsically luminescent self-assembled multilayers are far rarer. Bard has reported on an intriguing luminescent multilayer comprised of alternate layers of 1,6-hexane dithiols and Cu ions (see Figure 5.59),... 

Lvov, Y., Haas, H., Decher, G., Mohwald, H., Mikhailov, A., Mtchedlishvily, B., Morgunova, E., Vainshtein, B. (1994). Successive deposition of alternate layers of polyelectrolytes and a charged virus. Langmuir 10 4232-6. 

Y. Lvov, H. Haas, G. Decher, H. Mohwald, A. Mikhailov, B. Mtchedlishvily, E. Morgunova, B. Vanishtein, Successive Deposition of Alternate Layers of Polyelectrolytes and a Charged Virus , Langmuir, 10,4232 (1994)... 

A new area of polymer science termed nano-macromolecular chemistry [Eirich, 1993] also has relevance to future polymer blend technology and application. Langmuir-Blodget techniques allow for the formation of films of one molecule thickness. Utilizing polymerizable molecules for these films, a polymer molecule or network can yield a film with the thickness of several nanometers. Alternating layers comprised of different polymers could be prepared to yield specific optical or electrical properties. Polymerization of calix-arenes to yield molecular sieving membranes for gas separation has been discussed by Conner et al. [1993]. 

These complexes also formed stable Langmuir films, which could be transferred onto a range of various substrates to yield Langmuir-Blodgett (LB) films.A pyroelectric effect was observed in alternate layers incorporating an iridium complex, and the electronic hyperpolarizability of some chiral derivatives was measured. ... 

The Langmuir-Blodgett (LB) films are solid organized media, where the studies of the chemical reactivity lead to a better comprehension of molecular interactions in the solid state, and to a development of a true molecular engineering. The LB technique allows the building of different structures at the molecular level, such as mixed layers and alternating layers. These molecular assemblies appear as sets of molecules, which can interlock, to give rise to specific physico-chenucal properties. 

Langmuir-Blodgett films are deposited onto glass microscope slides, onto which an aluminium back electrode has been evaporated. The pyroelectric LB films studied consist of alternate layers of two materials,which produce a superlattice with a net polarisation. Buffer layers of the fatty acid, behenic acid, are included,both before and after deposition of the active layers. This ensures that the active layers are free from any interactions with the aluminium back and top electrodes. The capping layers also provide protection during top electrode evaporation. 

Figure 12.13 Alternate layer Langmuir trough showing the substrate attached to the rotating drum (R). All other symbols have the same meaning as in Figure 12.11.

Langmuir-Blodgett pseudocrystals. These are usually fabricated from the lead soap compounds (e.g., lead stearate) and are made by coating alternate layers of lead stearate molecules onto a suitable... 

Great interest has led to the development of Langmuir troughs with various meehanisms for the LB deposition of, for example, alternate layers of two different amphiphiles. In addition, techniques have been developed for overcoming problems related to the deposition of a second metal layer on top of a LB film already deposited on a metal substrate. 

Figure 3.5 (a) An example of a constant perimeter alternate-layer Langmuir trough showing fixed central barrier (FB) and the motor-driven rotary mechanism (R). Also shown are the barrier ribbon (B), the barrier drive motors (BD) which are attached to the movable barriers (MB), the surfece pressure monitors (W and II), and the substrate (S). (b) Also shown is the alternate layer molecular architecture realizable using the alternate layer technique. 

Various functional forms for / have been proposed either as a result of empirical observation or in terms of specific models. A particularly important example of the latter is that known as the Langmuir adsorption equation [2]. By analogy with the derivation for gas adsorption (see Section XVII-3), the Langmuir model assumes the surface to consist of adsorption sites, each having an area a. All adsorbed species interact only with a site and not with each other, and adsorption is thus limited to a monolayer. Related lattice models reduce to the Langmuir model under these assumptions [3,4]. In the case of adsorption from solution, however, it seems more plausible to consider an alternative phrasing of the model. Adsorption is still limited to a monolayer, but this layer is now regarded as an ideal two-dimensional solution of equal-size solute and solvent molecules of area a. Thus lateral interactions, absent in the site picture, cancel out in the ideal solution however, in the first version is a properly of the solid lattice, while in the second it is a properly of the adsorbed species. Both models attribute differences in adsorption behavior entirely to differences in adsorbate-solid interactions. Both present adsorption as a competition between solute and solvent. 

The rate of physical adsorption may be determined by the gas kinetic surface collision frequency as modified by the variation of sticking probability with surface coverage—as in the kinetic derivation of the Langmuir equation (Section XVII-3A)—and should then be very large unless the gas pressure is small. Alternatively, the rate may be governed by boundary layer diffusion, a slower process in general. Such aspects are mentioned in Ref. 146. 

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