POLY-SURFACE

Figure 4 Comparison of the m/e = 80 TPD spectra obtained after dosing a clean Au(poly) surface with d6-PC at 150 K with the filaments of the mass spectrometer, ion gauge and electron gun turned off (0.23 L d6-PC, curve a) and on (0.1 L d6-PC, curve b). The m/e = 80 TPD spectra shown in curve c were obtained by condensing ultrapurified d6-PC (1 L), which had been left in the doser for several days, onto the gold surface. Heating rate 3 K/s. (From Ref. 4.)...

Figure 6 Comparison between TPD (m/e = 48) spectra for TDF condensed at 130 K on a Li-covered Ag(poly) surface using electron bombardment from the rear (curve A) and resistive heating (curve B). Heating rate 5 K/s. (From Ref. 3.)...

Peaks of essentially the same shape and, therefore, derived from the same species, were observed for mle = 48, 44, 46, 30, 18, and 4 between 500 and 600 K for d6-PC condensed on Ag(poly) surfaces prepared under the same conditions described in the previous subsection for Au(poly). 

The primary aim of these experiments was to examine the TPD spectra of a genuine lithium alkyl carbonate formed on the surface of Au(poly) to determine whether the thermal decomposition of this UHV-synthesized material exhibits an m/e = 44 TPD spectra which resembles that observed in the TPD of d6-PC adsorbed on Li/Au(poly). The synthetic pathway employed is based on the sequential condensation of an ultrapurified alcohol (n-butanol, BuOH) onto a Li/ Au(poly) surface followed by exposure to C02 to form the desired alkyl carbonate. 

The TPD of a BuOH(20 L)/Li(17 ML)/Au(poly) surface, prepared by condensing ultrapurified BuOH on a Li/Au(poly) surface kept at 120 K, revealed, in addition to the features characteristic of bulk BuOH at 200 K, peaks for mle = 57 (curve a), 44 (curve b), 43 (curve c) and 2 (curve d), centered at 580 K (see Figure 27). Also noteworthy is the presence of a second mle = 2 peak at 435 K. A reaction pathway consistent with these data involves the dehydrogenation of BuOH to form the corresponding lithium butoxide (BuOLi) and lithium hydride, which at a sufficiently high temperature undergoes thermal decomposition to yield elemental Li and dihydrogen ... 

Support for this model was provided by the results of experiments in which a freshly prepared Li/Au(poly) surface was exposed to H2 at 140 K. As shown in Figure 28, the mle = 2 TPD in this case showed a clearly defined peak at about 440 K, attributed to the thermal decomposition of LiH [see Eq. (2)], which is very close to the peak temperature of the small feature observed in curve d in Figure 27. 

BuOH/Li/Au(poly) surfaces assembled at 120 K, heated to ca. 200 K to desorb bulklike BuOH, and cooled back to 120 K prior to the initiation of the TPD, showed the same high temperature features as those of nonheated surfaces prepared in the same fashion. A more detailed analysis of the high temperature TPD features will be given later in this section. 

Carbon Dioxide Adsorption on a BuOH/Li/Au(poly) Surface... 

The stability of the properties of polysilicon films to processing is not ideal. The structure and intrinsic stress of LPCVD-poly films created by different organizations but with the same deposition recipe were different [21]. The properties of LPCVD-poly can differ even on wafers from the same deposition run, due to small temperature fluctuations in the deposition furnace [25]. However, since several LPCVD-poly surface-micromachined sensors are in fact produced in high volumes for the automotive industry (e.g., by Analog Devices, Infineon, and Motorola), these literature data may not represent the current state of the art. 

SFG can provide considerable information regarding the buried interface that is of central importance to corrosion inhibition processes. A model system in this respect is the monolayer of benzotriazole (BTA) that forms beneath a thick multilayer of the same molecule on Cu. Two SFG studies have examined this system thus far [125, 126]. In the study by Schultz et al., SFG showed that BTA forms a relatively well-ordered monolayer on Cu(lOO) between -0.7 and -tO.2 V, while on Cu(lll) this order is only present at high potential. Titration with Cl showed that the monolayer was destabilized at lower Cl concentrations than those needed to destabilize the polymeric and somewhat more inaccessible multilayer. Work performed by Romero et al. using 5-methylbenzotriazole on Cu(poly) show that the 5-methylbenzotriazole is stable on the surface with no orientation changes with potential [125]. Similarly to the system studied by Schultz, the degree of preferential ordering of BTA on Cu(lll) seems to be less than that on the Cu(poly) surface. 

A single attempt was done to use the so-named electroscattering, a modnlation technique worked out by analogy with electroreflectance. Its application to Pt poly surfaces faceted in Arvia s style, in combination with linear optics, discovered the inhomogeneity of hydrogen adlayers at relatively low coverage, which was sensitive to microscopic snrface morphology. ... 

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