Langmuir-Blodgett alternating

Figure 6.6. Langmuir-Blodgett alternating multilayer with C v symmetry.

Figure 6.11. Langmuir-Blodgett alternate multilayers with hyperpolarizabilities associated with the individual layers and the multilayer according to Neal...

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]. 

Arden and Fromherz [51-53] have reported elegant work involving mono-layers of surfactants transferred to electrodes by the Langmuir-Blodgett method. Some results are shown in Figure 28.10. Two separate cationic dyes, thiacyanine (A) and oxacyanine (D), were synthesized with C18 alkyl chains, so that they would form oriented monolayers on water-air interfaces. By standard techniques, these were transferred alternatively or in sequence to n-ln203 electrodes, as... 

At least one patent has issued dealing with Langmuir-Blodgett (L-B) films containing polarizable side groups. Uniaxial films of 7,7-bis(hexadecylamino)-8,8-dicyanoquinodimethane can be cast which exhibit SHG.(101) Orientation is assured by alternating successive transferred layers of the polar substrate with arachidic acid layers. A P value of 500xl0 30 esu is claimed for the quinodimethane, but no information about SHG of the L-B films is provided. 

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),... 

Non-centrosymmetric Langmuir-Blodgett multilayers were also prepared by alternate deposition of nitrophenylhydrazone (dye FA06) and trimethylsilylcel-lulose (TMSC) [85]. Such waveguides had a relatively low loss of 3.5 dB cm 1 at 633 nm and the nonlinear material exhibited a reasonable of 19 pm V. With a fundamental wavelength of 1064 nm, a conversion efficiency of 10 4, corresponding to slope of the order of 10 8% W em 1 was demonstrated and further work was proposed to diminish the optical losses. 

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-... 

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)... 

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. ... 

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