Characterization, substrate chemical

The chemical and electronic properties of elements at the interfaces between very thin films and bulk substrates are important in several technological areas, particularly microelectronics, sensors, catalysis, metal protection, and solar cells. To study conditions at an interface, depth profiling by ion bombardment is inadvisable, because both composition and chemical state can be altered by interaction with energetic positive ions. The normal procedure is, therefore, to start with a clean or other well-characterized substrate and deposit the thin film on to it slowly at a chosen temperature while XPS is used to monitor the composition and chemical state by recording selected characteristic spectra. The procedure continues until no further spectral changes occur, as a function of film thickness, of time elapsed since deposition, or of changes in substrate temperature. 

Parry, A. D. and Edwards, R. (1994). Characterization of o-glucosyltransferases with activities toward phenolic substrates in alfalfa. Phytochemistry 37 655-661. Phamdelegue, M. H., Loublier, Y., Ducruet, V., Douault, P., Marilleau, R. and Etievant, P. (1994). Characterization of chemicals involved in honeybee-plant interactions. Grana 33 184-190. 

D. Inelastic neutron spectroscopy applied to molecules chemisorbed on catalytic substrates, tne model system considered in the previous section is of interest in demonstrating the degree to which neutron vibrational spectra can be interpreted on a well-characterized substrate. Unfortunately from the standpoint of this symposium, the graphite substrates in these experiments are not chemically active. Therefore, in this section, we wish to... 

Dong, P., and Un, Z.H. (2002) SERS smdies of self-adsorbed DNA monolayer -characterization of adsorption orientation of oligonucleotide probes and their hybridized helices on gold substrate. Chemical Physics Letters, 354, 458-465. 

The processing sequence for silicon dioxide (SiOi) depends on its specific use. For example, silica for use as inter-metallization insulation the order is deposition, densi-fication by annealing, and etching to the correct configuration. CVD processes for Si02 films can be characterized by chemical reaction type, the growth pressure, or deposition temperature. The choice of route is often dictated by requirements of the thermal stability of the substrate or the conformality. Table 5-4 summarizes selected... 

The upper limit to the thickness of dense silica coatings on hydroxylated surfaces that can be obtained with conventional coating techniques was found to be extended significantly by coating with monosilicic acid. An example with submicrometer a-alumina particles as a substrate showed dense, uniform coatings up to at least 800 A thick. The silica coatings and coating mechanism were characterized by chemical analysis,... 

They constitute therefore a substrate chemically similar to cellulose but provide a better characterized environment from the point of view of possible sites for adsorption. It should be a good medium to check for the correctness of the interpretation about the dye/cellulose interaction. 

Hawthorne H.M., Neville A., Troczynski T., Hu X., Thammachart M., Xie Y., Fu J., Yang Q. Characterization of chemically bonded composite sol-gel based alumina coatings on steel substrates. Surf. Coat. Technol. 2004 176 243-252... 

SPPO is a polymeric material with electric charges. Unlike charged polyamide membranes, SPPO TFC membranes are prepared by dip-coating of the surface of a porous substrate membrane. Even though it is well known that the pore structure of the substrate membrane governs the performance of THC membranes, as shown in various examples in this chapter, the criteria for the choice of the substrate membrane has not been established. This is mainly due to a lack of the method of surface characterization both chemically and physically. More research effort is called for in this important area of membrane design. 

Saturation kinetics are also called zero-order kinetics or Michaelis-Menten kinetics. The Michaelis-Menten equation is mainly used to characterize the interactions of enzymes and substrates, but it is also widely applied to characterize the elimination of chemical compounds from the body. The substrate concentration that produces half-maximal velocity of an enzymatic reaction, termed value or Michaelis constant, can be determined experimentally by graphing r/, as a function of substrate concentration, [S]. 

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