Cadmium arachidate LB film

X-ray diffraction has been applied to spread monolayers as reviewed by Dutta [67] and Als-Nielsen et al. [68], The structure of heneicosanoic acid on Cu and Ca containing subphases as a function of pH has been reported [69], as well as a detailed study of the ordered phases of behenic acid [70], along with many other smdies. Langmuir-Blod-gett films have also been studied by x-ray diffraction. Some recent studies include LB film structure just after transfer [71], variations in the structure of cadmium stearate LB films with temperature [72], and characterization of the structure of cadmium arachidate LB films [73], X-ray [74,75] and neutron reflectivity [76,77] data on LB films can be used to model the density profile normal to the interface and to obtain values of layer thickness and roughness. 

The second step, Figure 32b, consists of the covering of the styli with cadmium arachidate LB films. Monolayers of arachidic acid (in principle, it is also possible to use stearic or behenic acids with practically the same results) were spread over the surface of 10 " M CdCli water subphase in a Langmuir trough. The monolayer was compressed to a surface pressure of 27 mN/m and transfered onto styli by a vertical dipping technique. Up to six monolayers were deposited. 

Langmuir-Blodgett (LB) films prepared from cadmium arachidate LB films formed from dioctadecyldimethylammonium chloride (6) Size-quantized CdS particles formed in situ between the polar headgroups of the LB film Hexamethylphosphate-stabilized, size-quantized CdS... 

The adhesional stability of cadmium arachidate LB films was characterised in an aqueous environment in the geometry of a sessile drop and also by immersing the plate into the liquid. The results demonstrate that the measurement of the surface tension of the immersion liquid provides a sensitive tool to estimate the amount of the LB material removed from the solid substrate. However, the wettability of the LB film was... 

The mechanism of the removal of the cadmium arachidate LB film from a hydrophobic support, as the AFM study reveals, is a peeling-type detachment of a bilayer in water or an aqueous solution of CaCl2, while the dissolution of the LB film is more probable in the case of an NaCl solution. 

A unique but widely studied polymeric LB system are the polyglutamates or hairy rod polymers. These polymers have a hydrophilic rod of helical polyglutamate with hydrophobic alkyl side chains. Their rigidity and amphiphilic-ity imparts order (lyotropic and thermotropic) in LB films and they take on a F-type stmcture such as that illustrated in Fig. XV-16 [182]. These LB films are useful for waveguides, photoresists, and chemical sensors. LB films of these polymers are very thermally stable, as was indicated by the lack of interdiffusion up to 414 K shown by neutron reflectivity of alternating hydrogenated and deuterated layers [183]. AFM measurements have shown that these films take on different stmctures if directly deposited onto silicon or onto LB films of cadmium arachidate [184]. 

LB Films of Long-Chain Fatty Acids. LB films of saturated long-chain fatty acids have been studied since the inception of the LB technique. The most stable films of long-chain fatty acids are formed by cadmium arachidate deposited from a buffered CdCl2 subphase. These films, considered to be standards, have been widely used as spacer layers (23) and for examining new analytical techniques. Whereas the chains are tilted - 25° from the surface normal in the arachidic acid, CH2(CH2) gCOOH, films (24), it is nearly perpendicular to the surface in the cadmium arachidate films (25). 

The photoelectrochemical properties of CdS nanoparticles formed in LB films of cadmium arachidate on ITO glass (indium tin oxide-coated glass) were investigated [188]. The CdS particles were formed by exposure to H2S gas, and then the cadmium arachidate structure was regenerated by exposing the gas-treated films with aqueous solutions of CdCL. Gassing/immersion cycling increased the particle size from 2.3 0.7 nm after one cycle to 9.8 2.4 nm after five cycles. The 9.8-nm particles showed UV-visible ab-... 

In 1988 a method for the formation of CdS particles in Langmuir-Blodged (LB) matrix was suggested (Smotkin et al. 1988). LB film of cadmium arachidate was exposed to an atmosphere of H2S. During the reaction, the head groups of arachidic acid were proto-nated, and CdS was produced according to the following reaction ... 

Amplified photochemical quenching of carbazolyl fluorescence was observed in mixed LB films containing pure CUA and long-chain fatty adds [49,51], A pure CUA was synthesized from 2-nitrobiphenyl and 11-bromoundecanoic add methyl ester as reported previously [49,50]. Two monolayers of mixtures of CUA (fc= 0.02 - 0.50) and PA were deposited on five monolayers of cadmium arachidate at 15°C and 20 mN m 1 at pH 6.3. 

Uniform thin films of CdS were prepared by template-assisted electrochemical deposition on Au electrodes covered with Langmuir-Blodgett (LB) films of cadmium arachidate [168]. It was found that different CdS films could be produced depending on the type of LB film used. 

LB films prepared from a 3 2 charge-transfer complex of TMTTF and TCNQ and transferred to cadmium-arachidate (five layers) precoated sheets of polyethylene terephthalate ESR... 

Furthermore, the conformation and orientation of the hydrocarbon chains of MS in the MS-C20 binary and MS-C2o-AL18 ternary systems were investigated by using infrared absorption spectroscopy. In this respect, deuterated arachidic acid (C2o-d) and deuterated n-octadecane AL %-d) were utilized to separate infrared bands due to the hydrocarbon chains of MS from those arising from C2o and AL18. Fig. 26 shows polarized infrared spectra A of 10-layer LB films of pure cadmium arachidate (CdC20), MS-C20- binary and MS-C20-t/-AL18-t/... 

Since the two-dimensional packing of the monolayer on the aqueous subphase can differ from that observed after transfer as a LB film to a solid substrate, the molecular packing in the film in the two systems must be known. AFM studies of crystallite formation in LB films have been reported in regard to cadmium-arachidate monolayers. ... 

The molecular orientation of all-fran5-/J-carotene in the mixed LB film with barium stearate can be analyzed by the use of the axis model. This model was first proposed by Schmidt and Reich (1972) to analyze the molecular orientation of all-trani -lutein in the mixed LB film with cadmium arachidate. In their investigation, they only examined the absorbance at 45° incidence. In our investigation, we measured more fully the angular dependence of the absorbance at other than 45° incidence. Therefore, we believe that our analysis is more reliable than theirs. 

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