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Surface compound

Chemical Bond Formation (Chemisorption). This is the mechanism that leads to the formation of the strongest bonds between coUectors and mineral surfaces. Chemically adsorbed reagents usuaUy form surface compounds at the active waU sites. The flotation of calcite (CaCO ) and... [Pg.48]

Specific terms have been designated according to the function and composition of various roUs. Steel roUs that impose pressure, transmit heat, and emboss a pattern onto the fabric are known as pattern roUs. Flexible surface roUs that transport the fabric and permit pressure transmission to the fabric are termed bowl roUs or bowls. Bowl roUs are usually larger in diameter than pattern roUs. The material used to make these types of roUs is chosen according to the depth of surface smoothness to be placed on the fabric being calendered, and must be compatible with the pattern roU. Cellulose pulp, cotton, wool, cotton—wool mixtures, com husk, and various polymer materials are used as fillers for the roU surface compound. [Pg.156]

Incompletely Characterized Carbon Sulfides. A poorly characterized black soHd, known as carsul, occurs as a residue ia sulfur distillation or as a precipitate ia molten Frasch sulfur (12,13). Although this material may approach the composition of a carbon sulfide, it is more likely also to contain some chemically bound hydrogen and possibly other elements. Carbon—sulfur surface compounds of the formula C S, where xis greater than 4,... [Pg.129]

Compound (1) decomposes to form dichloroacetyl chloride, which in the presence of water decomposes to dichloroacetic acid and hydrochloric acid (HCl) with consequent increases in the corrosive action of the solvent on metal surfaces. Compound (2) decomposes to yield phosgene, carbon monoxide, and hydrogen chloride with an increase in the corrosive action on metal surfaces. [Pg.23]

Fig. 2.29. Formation of surface compounds on Fe-15%Cr alloys by cosegregation of chromium and a non-metallic element [2.160]. (a) nitride, (b) carbide, (c) sulfide. Fig. 2.29. Formation of surface compounds on Fe-15%Cr alloys by cosegregation of chromium and a non-metallic element [2.160]. (a) nitride, (b) carbide, (c) sulfide.
Lithium carbonate and hydrocarbon were identified in XPS spectra of graphite electrodes after the first cycle in LiPF6/EC-DMC electrolyte [104]. Electrochemical QCMB experiments in LiAsF6/EC-DEC solution [99] clearly indicated the formation of a surface film at about 1.5 V vs. (Li/Li+). However the values of mass accumulation per mole of electrons transferred (m.p.e), calculated for the surface species, were smaller than those of the expected surface compounds (mainly (CF OCC Li ). This was attributed to the low stability of the SEI and its partial dissolution. [Pg.441]

The active component of the chromium oxide catalyst is a surface compound of Cr(VI). In the case of silica as a support this stage may be presented by the schemes ... [Pg.176]

The specific behavior of surface compounds, being the propagation centers of polymerization catalysts, are mainly determined by two of their features the coordinative insufficiency of the transition metal ion and the presence of the transition metal-carbon bond. [Pg.202]

The formation of surface compounds of low-valent ions of transition metals on the surface of the support. In particular, fixing organometallic compounds on the support surface, it may be possible to stabilize coordi-natively insufficient complexes of transition metals and to obtain highly active catalysts. In the ideal case a complete use of the transition metal in the formation of the propagation centers can be achieved. [Pg.204]

The undissociated NO molecules and the dissociation products can participate in secondary reactions in the mixed alkali-NO overlayers and result both in products which immediately desorb (e.g. N2) or further decompose (e.g. N20), and in alkali stabilized compound-like products (nitrite-like salts). As in the case of CO or C02 adsorption, the formation of such surface compounds is favoured at elevated temperatures and at alkali coverages higher than those corresponding to the work function minimum. [Pg.46]

Direct electrostatic ( through the vacuum ) dipole attraction or repulsion which, in the case of attraction, may lead even to surface compound formation. [Pg.83]

Subsequent elegant work by Lambert and coworkers61 has shown that, while under UHV conditions the electropumped Na is indistinguishable from Na adsorbed by vacuum deposition, under electrochemical reaction conditions the electrochemically supplied Na can form surface compounds (e.g. Na nitrite/nitrate during NO reduction by CO, carbonate during NO reduction by C2FI4). These compounds (nitrates, carbonates) can be effectively decomposed via positive potential application. Furthermore the large dipole moment of Na ( 5D) dominates the UWr and O behaviour of the catalyst-electrode even when such surface compounds are formed. [Pg.254]

At elevated temperatures in the presence of oxygen the aluminium oxide layer catalyzes the formation of blue fluorescent aluminium oxide surface compounds with 4-hydroxy-3-oxo-A -steroid structures [4]. Aluminium oxide acts as an oxidation catalyst for an activated methylene group. [Pg.23]

The observed complexity of the Se(IV) electrochemistry due to adsorption layers, formation of surface compounds, coupled chemical reactions, lack of electroactivity of reduction products, and other interrelated factors has been discussed extensively. Zuman and Somer [31] have provided a thorough literature-based review with almost 170 references on the complex polarographic and voltammetric behavior of Se(-i-IV) (selenous acid), including the acid-base properties, salt and complex formation, chemical reduction and reaction with organic and inorganic... [Pg.70]

It is important to point out that in the discussion that follows the term "Na coverage" is used this does not imply that the promoter is thought to be present in the form of chemisorbed metallic sodium as it would be in vacuum. The reactive gas atmosphere is expected to lead to the formation of surface compounds of Na, and single crystal data indicate... [Pg.518]

In conjunction with latest progress in quantum chemistry the availability of vast experimental data makes it possible to anal)rze the character of possible centers of adsorption of particles of various gases as well as type, chemical and electron properties of surface compounds formed during interaction of adsorption particles with adsorption centers. [Pg.93]

Indeed, in this case the formation of neutral surface compound (Me Of-) is accompanied by binding of neutral superstoichiometric Me and, therefore, decrease in concentration of donors responsible for dope electric conductivity of adsorbent. In the case when the formed surface state possesses sufficient electron affinity one can-... [Pg.121]

Taking into account above considerations for the rate of the change in concentration of chemisorbed radicals forming unstable organometal surface compounds we obtain the following expression... [Pg.149]

Intriguing results were obtained for photolysis of chemisorbed layers of methyl radicals on oxide films [18]. Experiments confirmed the hypothesis [19] concerning the natime of surface compounds produced in chemisorption of elementary radicals on metal oxides. [Pg.233]

Upon disabling the Hg flux, the surface compounds of mercury decompose at elevated temperatures ... [Pg.287]

It has been already mentioned in preceding section that in process of ordering of disordered adsorbents the energy get released which is sufficient to brake the bonds in the surface compounds. Therefore, the emission of initially adsorbed active particles due to disorder relaxation should be studied in disorder surfaces. It is very convenient to use for such studies the amorphous antimony with adsorbed hydrogen atoms. The properties of thin antimony films have been studied in substantial detail due to their use in manufacturing of photocathodes [12]. [Pg.355]

As a function of the surface potential the electron work function for a given material depends on the state of the surface of that material (adsorption, the presence of surface compounds, etc.). For crystalline substances (see Table 3.1), various crystal faces have various electron work function values, which can be measured for single crystals. For poly crystalline substances, the final value of the electron work function depends on the contribution of the individual crystal faces to the entire area of the phase and the corresponding electron work functions the final value of the work function, however, is strongly dependent on the experimental method used for the measurement. [Pg.165]

Bewick, A., and M. Fleischmann, Formation of surface compounds on electrodes, in Topics in Surface Chemistry (Eds E. Kay and P. S. Bagres), p. 45, Plenum Press, New York, 1978. [Pg.395]

Although ribosomal proteins are readily observed as in Figures 13.7 and 13.8 altered matrix conditions can alter the relative ionization of bacterial whole-cell compounds. A systematic analysis involving laser power/fluence and sample preparation conditions reveals that if the concentrated trifluo-roacetic acid is added and the laser power increased above optimal conditions, ionization of bacterial surface compounds can be enhanced. Figure 13.9 is the resulting 9.4 T MALDI-FTMS, seen are both the Braun s lipoprotein56,57 and the Murein lipoprotein. Both of these compounds are complex combinations of hydrocarbon lipids attached to a protein base. This is the first MALDI-FTMS observation of surface proteins desorbed directly from whole cells by influencing ionization conditions. [Pg.291]

It has also to be remembered that the band model is a theory of the bulk properties of the metal (magnetism, electrical conductivity, specific heat, etc.), whereas chemisorption and catalysis depend upon the formation of bonds between surface metal atoms and the adsorbed species. Hence, modern theories of chemisorption have tended to concentrate on the formation of bonds with localized orbitals on surface metal atoms. Recently, the directional properties of the orbitals emerging at the surface, as discussed by Dowden (102) and Bond (103) on the basis of the Good-enough model, have been used to interpret the chemisorption behavior of different crystal faces (104, 105). A more elaborate theoretical treatment of the chemisorption process by Grimley (106) envisages the formation of a surface compound with localized metal orbitals, and in this case a weak interaction is allowed with the electrons in the metal. [Pg.148]

Surface limited reactions are well known in electrochemistry, and are generally referred to as underpotential deposits (UPD) [83-88], That is, in the deposition of one element on a second, frequently the first element will form an atomic layer at a potential under, or prior to, that needed to deposit the element on itself. One way of looking at UPD is that a surface compound, or alloy, is formed, and the shift in potential results from the free energy of formation of the surface compound. [Pg.8]

Fig. 1.2 A comparison of total ion chromatograms (GC-MS TIC) of selected axillary skin surface compounds for A a female, B a male (1), C a male (2) human subjects... Fig. 1.2 A comparison of total ion chromatograms (GC-MS TIC) of selected axillary skin surface compounds for A a female, B a male (1), C a male (2) human subjects...
These experiments also show the value of NEXAFS as a technique for following the kinetics of surface processes. We have shown that experiments can be tailored so a specific reaction can be studied, even if gas evolution is not involved. This represents an advantage over thermal desorption experiments, where several steps may be required in order to desorb the products to be detected. Another advantage of NEXAFS is that rates are measured isothermally, so the kinetic parameters can be determined with accuracy. Finally, NEXAFS is not a destructive technique, so we need not to worry about modifying the surface compounds while probing the system, as would be the case with other techniques such as Auger electron spectroscopy. [Pg.139]


See other pages where Surface compound is mentioned: [Pg.381]    [Pg.251]    [Pg.232]    [Pg.47]    [Pg.324]    [Pg.822]    [Pg.235]    [Pg.431]    [Pg.178]    [Pg.183]    [Pg.189]    [Pg.213]    [Pg.43]    [Pg.393]    [Pg.520]    [Pg.477]    [Pg.132]    [Pg.141]    [Pg.89]    [Pg.16]    [Pg.21]    [Pg.164]   
See also in sourсe #XX -- [ Pg.58 ]

See also in sourсe #XX -- [ Pg.218 ]




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A Cleavage, carbonyl compounds potential energy surfaces

Adsorption of Ionized Organic Compounds from Aqueous Solutions to Charged Mineral Surfaces

Adsorption surface compound formation

Amphiphilic compounds surface activity

Carbon surface compounds

Carbon-sulfur surface compounds

Compound nonpolar surfaces

Compound polar surfaces

Compound semiconductors surface bulk properties

Compound semiconductors surface determination

Compound surface electronic properties

Compound surface optical analysis

Compound surface structure theoretical

Compound surfaces under growth condition

Compound wurtzite materials surfaces

Compounds with support surfaces, reaction

Inorganic compounds surface tension

Intermetallic compound surfaces

Intermetallic compound surfaces effect characteristics

Ionic compounds surfaces

Metal oxide-based compounds surface defects

Metal oxide-based compounds surface modifications

Metal surface compounds

Metal surfaces compounds Electron energy loss

Non-ionic surface active compounds

Nonionized compounds surface-active agents

Onuki and A. Hasegawa, Fermi surfaces of intermetallic compounds

Organic compounds analysis polymer surfaces

Organic compounds surface tensions

Organomolybdenum Compounds in Surface Engines Protection

Organosilane compounds surface preparation

Organosulfur compounds, gold surface

Reactivity of Organometallic Compounds with Metallic Surfaces

Reduction of saturated surface compounds

Residue and Surface Compounds

Semiconductors, compound, surface

Silver compounds surface modified electrodes

Sorption of Nonionic Organic Compounds to Inorganic Surfaces in Water

Surface Compound Formation

Surface Compounds of Carbon

Surface active compounds estimation

Surface carbonaceous compounds

Surface cationic compounds

Surface chemistry compounds

Surface clean compound surfaces, chemical

Surface coverage, organic compounds

Surface coverage, organic compounds metal oxide surfaces

Surface decomposition intermetallic compound

Surface energies of cubic diamond structure compounds

Surface energy aspects compounds

Surface energy ionic compounds

Surface metallic compounds

Surface reactions, binary compounds

Surface tension compounds

Surface treatments chromium compounds

Surface waters organophosphorus compounds

Surface-Active Compounds as Forest-Industry By-Products

Surface-active agents (surfactants compounds

Surface-active compounds

Surface-active compounds cellulose

Surfaces and Molten Ionic Compounds

Surfaces of Compound Semiconductors

Transition metal surface compounds

Using electrochemical and surface analytical techniques to evaluate corrosion protection by rare earth metal (REM) compounds

Water surface active compounds

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