Silanes, characterization

Gentle, T.E., Schmidt, R.G., Naasz, B.M., Gellman, A.J. and Gentle, T.M., Organofunc-tional silanes as adhesion promoters direct characterization of the polymer/silane inter-phase. J. Adhes. Sci. Technol., 6, 307-316 (1992). 

TABLE 8.2 Characterization Data for Poly[carbo(dimethyl)silane]s... 

This section treats the plasma physics and plasma chemistry of the typical silane-hydrogen RF discharge, with occasional examples that employ a somewhat higher excitation frequency. Electrical characterization of the discharge is followed by an analysis of the silane chemistry. An appropriate set of gas phase species is presented, which are then used in the modeling of the plasma. A comparison is made between modeling results and experimental work in ASTER. Extension to 2D modeling is presented as well. 

In order to relate material properties with plasma properties, several plasma diagnostic techniques are used. The main techniques for the characterization of silane-hydrogen deposition plasmas are optical spectroscopy, electrostatic probes, mass spectrometry, and ellipsometry [117, 286]. Optical emission spectroscopy (OES) is a noninvasive technique and has been developed for identification of Si, SiH, Si+, and species in the plasma. Active spectroscopy, such as laser induced fluorescence (LIF), also allows for the detection of radicals in the plasma. Mass spectrometry enables the study of ion and radical chemistry in the discharge, either ex situ or in situ. The Langmuir probe technique is simple and very suitable for measuring plasma characteristics in nonreactive plasmas. In case of silane plasma it can be used, but it is difficult. Ellipsometry is used to follow the deposition process in situ. 

Matsuda and Hata [287] have argued that the species that are detectable using OES only form a very small part (<0.1%) of the total amount of species present in typical silane deposition conditions. From the emission intensities of Si and SiH the number density of these excited states was estimated to be between 10 and 10 cm", on the basis of their optical transition probabilities. These values are much lower than radical densities. lO " cm . Hence, these species are not considered to partake in the deposition. However, a clear correlation between the emission intensity of Si and SiH and the deposition rate has been observed [288]. From this it can be concluded that the emission intensity of Si and SiH is proportional to the concentration of deposition precursors. As the Si and SiH excited species are generated via a one-electron impact process, the deposition precursors are also generated via that process [123]. Hence, for the characterization of deposition, discharge information from OES experiments can be used when these common generation mechanisms exist [286]. 

The radii of both orifices can be either on a micrometer or a submicrometer scale. If the device is micrometer-sized, it can be characterized by optical microscopy. The purposes of electrochemical characterization of a dual pipette are to determine the effective radii and to check that each of two barrels can be independently polarized. The radius of each orifice can be evaluated from an IT voltammogram obtained at one pipette while the second one is disconnected. After the outer surface of glass is silanized, the diffusion-limiting current to each water-filled barrel follows Eq. (1). The effective radius values calculated from that equation for both halves of the d-pipette must be close to the values found from optical microscopy. 

Without adequate silanization, an aqueous film can short-circuit the d-pipette by linking its two halves. In the absence of a surface aqueous layer the currents flow between each of two pipettes and the external reference electrode. In contrast, when the liquid film connects two orifices, the current flows directly from one barrel to the other. Two experiments allowing the distinction between these two cases were carried out using a well-characterized reaction of potassium transfer from water into DCE facilitated by dibenzo-18-crown-6 (DB18C6) [11]... 

In this work seven copolymers, including dimethyl-co-cyclohexylmethyl, cyclohexylmethyl-co-n-propylmethyl, cyclohexylmethyl-co-n-propylmethyl, phenylmethyl-co-isopropylmethyl, phenylmethyl-co-n-propy lmethyl, phenylmethyl-co-cyclohexylmethyl and n-propylmethyl-co-isopropylmethyl silane with varying percentages of the respective comonomers in the feed have been prepared and characterized. 

The bi- and tridentate phosphines dppp (l,3-bis(diphenylphosphino)propane) and dppep (bis (2-diphenylphosphinoethyl)phenylphosphine) have been complexed with Co and their divalent four- and five-coordinated thiophenolate complexes Co(dppp)(SPh)2 and Co(dppep)(SPh)2 have been isolated and structurally characterized.379 Somewhat related to dppp is the bidentate silane Ph2PCH2SiMe2CH2PPh2, which forms high-spin, pseudo-tetrahedral dihalocobalt(II) complexes.380... 

Olson LG, Lo YS, Beebe TP Jr, Harris JM (2001) Characterization of silane-modified immobilized gold colloids as a substrate for surface-enhanced Raman spectroscopy. Anal Chem 73 4268-4276... 

Further reactions of 5/6 with the sterically less bulky silanes HSiCl3, Ph2SiHCl and Ph2SiH2 give the thermo-labile /x-biscarbyne complex 14, which has been spectroscopically characterized (Table 1). In these cases, formation of the silyl hydrides 11, 13, 15 and 16 as products of an oxidative addition at the 16e -complex generated from 6 (attack at Mn) becomes important. 

Given the ability of 14 electron fragments [(dtbpm)Pt(O)] and [(dcpm)Pt(O)] to activate C-H and C-Si bonds of inert organosilanes under very mild reaction conditions, it was of course no big surprise that Si-H activation reactions of silanes are possible as well. Hydrido-silyl complexes were formed in practically quantitative reactions if 14 or IS were used as precursors for the [(dtbpm)Pt(O)] fragment. Examples of Si-H insertion products, all stable, isolable compounds which could be fully characterized, are 25 - 27, and others have been made. 

Another hindered silane, di-t-butyldichlorodisilane, gives high yields of the reactive divalent species, di-t -butylsilylene, which was characterized by its insertion reactions into Si-H bonds(35) ... 

The other well-characterized metal (i.e., iridium) for trans-addition processes to terminal alkynes suffers from similar limitations.55,5511 53f While iridium provides good selectivity for (Z)-/3-vinylsilanes (Table 4, G) with MePh2SiH (Table 4, entry 1), silanes with electron withdrawing groups (entry 6) and bulky alkynes (entry 4) exhibit significant deterioration in selectivity.25... 

In this section, we comprehensively focused on the controlled synthesis, chiroptical characterization, and manipulation of optically active poly(dialkyl-silane)s. Although many artificial polymers adopting preferential screw sense... 

It is considered that, if ideal, optically active poly(alkyl(aryl)silane) homopolymer and copolymer systems could be obtained which had stiffer main-chain structures with longer persistence lengths, it should be possible to clarify the relationship between the gabs value and the chiral molar composition. The magnitude of the chirality of the polyisocyanates allowed precise correlations with the cooperativity models.18q In the theory of the cooperative helical order in polyisocyanates, the polymers are characterized by the chiral order parameter M, which is the fraction of the main chain twisting in one helical sense minus the fraction of the main chain twisting in the opposing sense. This order parameter is equal to the optical activity normalized by the value for an entirely one-handed helical polymer. The theory predicts... 

Suzuki, N. and Ishida, H A review on the structure and characterization techniques of silane/matrix interphases, Macromol. Symp., 108, 19-53 (1996). 

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