Alternating Langmuir-Blodgett films

Nagamura, T., Sakaguchi. H., Matsuo, T. Photochemical modulahon of second order nonhnear optical properties of alternate Langmuir-Blodgett films containing ruthenium) ll)-bipyridine complexes. Thin Solid Films 210-211, 160-162 (1992)... 

Li, J.-X., GardeUa, J.A. Jr., McKeown, P.J. (1995) A quantitative time-of-flight secondary ion mass spectrometry study of ion formation mechanisms using acid-base alternating Langmuir-Blodgett films. Appl. Surf Sci., 90, 205-215. 

The formation of multilayer structure can be carried out by several ways 1) adsorption on liquid/liquid interface - Langmuir-Blodgett films [5,6] 2) adsorption on solid/liquid interface - alternate adsorption of oppositely charged polyelectrolytes (PE) and surfactants on flat surfaces or spherical particles [7,8], To control the process of multilayer systems formation, it is necessary to under-... 

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. 

I. Ledoux, D. Josse, P. Fremaux, J.P. Piel, G. Post, J. Zyss, T. McLean, R.A. Hann, P.F. Gordon and S. Allen, Second harmonic generation in alternate non-linear Langmuir-Blodgett films. Thin Solid Films 160 217 (1988). 

FIGURE 8.21. Insoluble monolayer films can, with careful work, be deposited onto solid substrates from the liquid surface. The so-called Langmuir-Blodgett films will usually have alternating molecular orientations (a) first-layer deposition with the head (or tail) toward the solid substrate and (h) the second-layer head-to-head or tail-to-tail in a Y film orientation. Under some conditions it is possible to produce an X film with head-to-tail orientation (c). 

In this way (multi)layers, referred to as Langmuir-Blodgett films or, for short, LB films, are formed with alternating head-head and tail-tail orientations of the surfactant molecules. This type of transfer in which a monolayer is deposited during each passage of the substrate through the interface is called F-transfer. It follows that with hydrophihc supports at the end of each completed cycle films containing an odd number of layers are deposited, whereas for hydrophobic surfaces an even number of layers are transferred. 

The topochemical diacetylene photopolymerization is apphcable to various organized structures, including Langmuir-Blodgett films, liposomes, vesicles, and self-assembled monolayers (SAMs) on metal oxide or graphite surfaces. Scheme 3.14 depicts an assembly of diacetylene molecules and the subsequent photopolymerization at 254 nm. At ambient temperatures, the polymerization proceeds as a chain reaction by 1,4-addition, and results in alternating ene-yne polymer chains with exclusive trans selectivity. The quantum yield for initiation is low (about 0.01) [60]. 

Similar problems with Au deposition on SAMs and Langmuir-Blodgett films have been reported extensively, as has layer damage by An alternative cold deposition method based on diffu-... 

Semiconductor particle formation between Langmuir-Blodgett (LB) films is an alternative and promising approach to band-gap engineering [662-666]. The ease of formation of self-assembled (SA) films [183-185,203-246] promoted the incorporation of semiconductors into these media [663, 710]. 

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