Title: Surface Review and Letters

Title: Surface Science

ISO Abbreviated Title: Surf. Sci.

JCR Abbreviated Title: Surf Sci

ISSN: 0039-6028

Issues/Year: 36

Journal Country Netherlands

Language: English

Publisher: Elsevier Science BV

Publisher Address: PO Box 211, 1000 AE Amsterdam, Netherlands

Subject Categories:

Chemistry, Physical: Impact Factor 2.198, 23/91 (2000)

Onoda, Jr., G.Y. and De Bruyn, P.L. (1966), Proton adsorption at ferric oxide/aqueous solution interface. I. A kinetic study of adsorption. Surface Science, 4 (1), 48-63.

Full Text: S\Sur Sci4, 48.pdf

Abstract: A kinetic study of the adsorption of potential-determining ions (Hⁱ⁺) at the ferric oxide (-Fe₂O₃)/solution interface is reported. The experimental results obtained by potentiometric titrations of suspensions of the synthetically-prepared solid indicate that a two-step process operates at the interface. The observed results may be explained by a rapid adsroption (or desorption) of protons at the surface of the oxide, followed by the slow diffusion of the adsorbed proton into (or out of) a goethite-like interphase separating the bulk anhydrous oxide from the solution phase. Corroborative evidence for the proposed model and mechanism is supplied.

Scheer, M.D. and McKinley, J.D. (1966), Adsorption kinetics of nitrogen on Rhenium. Surface Science, 5 (3), 332-344.

Full Text: S\Sur Sci5, 332.pdf

Abstract: The adsorption of room temperature nitrogen on atomically clean polycrystalline rhenium has been studied. The sticking coefficients at zero coverage were found to be 0.060, 0.009, and 0.007 at rhenium surface temperatures of 205, 300, and 373 °K respectively. These values are between one and two orders of magnitude smaller than those in the nitrogentungsten system. The dependence of the sticking coefficient upon surface coverage and temperature could be accounted for by assuming an intermediate state weakly bound to an adsorption site. These sites were assumed to be uniformly distributed over the surface. Their concentration was found to be less than 1/10 of the number of substrate-rhenium atoms/cm². The binding energies of the intermediate state and the permanently adsorbed state were in the ratio of about 1: 20 for both the nitrogen-rhenium and nitrogen-tungsten systems. In view of this similarity, it is difficult to account for the large difference in sticking probabilities unless one assumes that tungsten absorbs energy from the intermediate binding state much more efficiently than does the rhenium.

Hoory, S.E. and Prausnit, J.M. (1967), Effect of surface heterogeneity on adsorption isotherm at very low coverage. Surface Science, 6 (3), 377-387.

Full Text: S\Sur Sci6, 377.pdf

Abstract: Two extensions are presented for Ross’ theoretical model of surface heterogeneity. First, consideration is given to the variation of vibrational energy of an adsorbed molecule on different surface patches, each of which is characterized by a particular adsorption potential. Second, consideration is given to the function used for describing the distribution of the adsorption potential. Both extensions are tested on data by Steele and Halsey for adsorption of argon on heterogeneous carbon (black pearls). There does not appear to be any significant advantage in taking into account variations of vibrational energy from patch to patch. Further, the inclusion of negative adsorption potentials in the Gaussian distribution function does not introduce any difficulties, data reduction using the Gaussian distribution is as good as that obtained with the log-normal distribution which includes only positive adsorption potentials.

Bérubé, Y.G., Onoda, Jr., G.Y. and De Bruyn, P.L. (1967), Proton adsorption at ferric oxide/aqueous solution interface. II. Analysis of kinetic data. Surface Science, 7 (3), 448-461.

Full Text: S\Sur Sci7, 448.pdf

Abstract: A quantitative study of the time-dependent abstraction of H⁺ and OH^- ions from solution by crystalline Fe₂O₃ precipitates is reported. The experimental information was gathered by potentiometric titrations of oxide suspensions, by observation of pH drift with time after rapid displacement of the pH of the solution initially equilibrated with the solid at the zpc, and by tritium exchange between the tritiated oxide and pure water.

On the assumption that the slow step is controlled by diffusion of protons into or out of a hydrated surface region, an analysis of the pH drift experiments yields a diffusion coefficient for protons approximately equal to 10^-21 cm²/sec and an activation energy of 20 kcal/mole. The tritium exchange experiments confirm the presence of a hydrated surface layer with an estimated thickness not exceeding 26 Å and yield a self-diffusion coefficient of about 10^-21 cm²/sec. Although both these experimental approaches gave results in support of the proposed phenomenological description of the slow step, the magnitude of the observed abstractions cannot be completely accounted for by proton diffusion into the solid. Comparison with experimental studies on TiO₂, ZnO and Al₂O₃ suggests that the diffusion model proposed by Onoda and de Bruyn¹) is to be complemented by a surface anion exchange between OH^- and other univalent inorganic anions in order to account for the experimental facts.

Gottwald, B.A. and Haul, R. (1968), Adsorption kinetics. III. Determination of adsorption isotherms from molecular flow experiments. Surface Science, 10 (1), 76-90.

Full Text: S\Sur Sci10, 76.pdf

Abstract: The transient molecular flow of sorbable gases through a capillary has been treated mathematically: Corresponding to the delay of the outflowing process (‘time lag’) the inflow of the gas is also affected by adsorption (‘time lead’). The evaluation of adsorption isotherms from molecular flow experiments is described. Since the whole pressure range below the inlet pressure is covered during a single experiment studies of transient molecular flow are particularly suited for obtaining and characterizing adsorption isotherms at low surface coverages. The influence of the adsorption isotherm on the parameters of the transient flow –– an initial delay and a stretch in time –– is discussed. Conditions are specified, under which an eventual transition of a non-linear (e.g. Dubinin-Radushkevich-) to a Henry-isotherm could become apparent at extremely low surface coverages.

Harris, L.B. (1968), Adsorption on a patchwise heterogeneous surface, mathematical analysis of the step-function approximation to the local isotherm. Surface Science, 10 (2), 129-145.

Full Text: S\Sur Sci10, 129.pdf

Abstract: In order to estimate the energetic heterogeneity of an adsorbent, the theoretically ‘correct’ local isotherm describing adsorption on an individual surface patch is frequently approximated by a step function. The present paper presents a general method with which the errors incurred by using this approximation can be appraised. The differences between the approximate and the exact distribution are calculated for two forms of the latter when the Langmuir local isotherm is assumed to be correct and is approximated by a step function. The differences are discussed and are shown to be directly related to the form of the Langmuir isotherm.

Misra, D.N. (1969), Adsorption on heterogeneous surfaces: A Dubinin-Radushkevich equation. Surface Science, 18 (2), 367-372.

Full Text: S\Sur Sci18, 367.pdf

Abstract: A site energy distribution function for a ‘generalized form’ of the Dubinin-Radushkevich equation has been obtained by the Stieltjes transform method of Sips. The distribution function is identical in form to the one empirically obtained by Hobson and Armstrong on the basis of the potential theory of adsorption. The Langmuir adsorption isotherm is presumed to be valid for the individual ‘homotattic’ sites and, therefore, the generalized Dubinin-Radushkevich equation and hence the distribution function are only valid within the domain of conditions imposed on the Langmuir isotherm.

Knözinger, H. and Jeziorowski, H. (1970), Adsorption behavior of thorium xoide. I. Kinetics of adsorption of ethanol, ethylether and water. Surface Science, 22 (1), 111-124.

Full Text: S\Sur Sci22, 111.pdf

Abstract: From adsorption kinetics the intraparticle diffusion coefficients for water, diethyl ether and ethanol have been calculated for a microporous thorium oxide sample to be of the order of 10⁻¹³–10⁻¹⁴ cm²/sec in the temperature range between 100 and 200°C at 80 Torr. It can be shown that the mass transport proceeds in the adsorbed phase only, most probably by hydrodynamic flow of an adsorbed liquid film.

Knözinger, H. and Jeziorowski, H. (1970), Das adsorptionsverhalten von thoriumoxid I. Kinetik der adsorption Von Äthanol, Äthyläther und Wasser. Surface Science, 22 (1), 111-124.

Full Text: S\Sur Sci22, 111.pdf

Abstract: From adsorption kinetics the intraparticle diffusion coefficients for water, diethyl ether and ethanol have been calculated for a microporous thorium oxide sample to be of the order of 10^-13–10^-14 cm²/sec in the temperature range between 100 and 200°C at 80 Torr. It can be shown that the mass transport proceeds in the adsorbed phase only, most probably by hydrodynamic flow of an adsorbed liquid film.

Gasser, R.P.H., Szczepur, A.K., Overton, J.M. and Morton, T.N. (1971), Kinetic isotope-effect in hydrogen adsorption on tungsten. Surface Science, 28 (2), 574-580.

Full Text: S\Sur Sci28, 574.pdf

Abstract: A kinetic isotope effect in the rate of adsorption of hydrogen on polycrystalline tungsten has been sought, following the report of such an effect on a (100)-oriented tungsten crystal. However, no difference between the isotopes could be detected. The reason for these discordant results may lie either in an unidentified experimental artefact or in a genuine difference between oriented and polycrystalline surfaces.

King, D.A. and Wells, M.G. (1972), Molecular beam investigation of adsorption kinetics on bulk metal targets: Nitrogen on tungste. Surface Science, 29 (2), 454-482.

Full Text: S\Sur Sci29, 454.pdf

Abstract: An ultra high vacuum molecular beam technique for the study of the kinetics of the interaction of reactive gases with well-defined metal surfaces is described. Well collimated beams of nitrogen molecules, with an accurately measured intensity of 10¹² to 10¹³ molecules cm^-2 sec^-1 over a target area of ~ 4×10^-2 cm², are obtained using a series of five chambers differentially pumped with a combination of high speed diffusion pumps and strategically deposited titanium getter films. Out-of-beam leakage into the adsorption cell was < 10⁸ molecules sec^-1. A method is described for obtaining absolute values of sticking probabilities and surface coverages with a high degree of accuracy.

For nitrogen on a polycrystalline tungsten foil, sticking probabilities and their coverage profiles were found to be independent of incident molecular beam angle, over a range of 60°, with an initial sticking probability, s₀, at 300 K of 0.61±0.02. The sticking probability profile is monotonie over the range examined, and is theoretically described in terms of a modified form of Kisliuk’s precursor state model, with self-consistent parameters. On a linear plot, the sticking probability extrapolates to zero at a coverage of 3.0(±0.5)×10¹⁴ molecules cm². On the W(111) plane s₀ was found to be 0.08±0.01, and the sticking probability falls linearly with increasing coverage, with a saturation coverage of 1.2(±0.2)×10¹⁴ molecules cm^-2. It is argued that adsorption sites on the (111) plane are created by the presence of surface vacancies or randomly distributed W atoms on the perfect (111) surface. Within the limits of detection of the molecular beam technique no nitrogen adsorption could be detected on the (110) plane of tungsten, in agreement with previous work.

López-Sancho, J.M. and De Segovia, J.L. (1972), Adsorption kinetics and electron desorption of O₂ on polycrystalline tungsten. Surface Science, 30 (2), 419-439.

Full Text: S\Sur Sci30, 419.pdf

Abstract: Electron desorption parameters and sticking coefficients of O₂ adsorbed on polycristalline tungsten have been studied. Two clearly-distinct adsorption states, ₁ and ₂, are identified with desorption energies of 110 kcal/mol and 96 kcal/mol, the desorption temperatures are 2150 and 1900°K respectively. Desorption from ₁ yields atomic oxygen and from ₂ a complex WO_n. The populations are n₁ = 8.7×10¹⁴ molecules/cm² and n₂ = 2×10¹⁴ molecules/cm² at 77 °K. The sticking coefficients, as a function of coverage for both states, have been determined (s₀₁  1, s₀₂ = 0.8 at 77 °K and s₀₁ = 0.98, s_0v2 = 0.76 at 300 °K), being the experimental points fitted by a theoretical expression. From the values of so, (E_A - E_P) for both states has been calculated, E_A being the activation energy of chemisorption and E_P the depth of the potential well in the preadsorbed state.

Procop, M. and Völter, J. (1972), Adsorption of hydrogen on platinum. I. Adsorbed amounts, kinetics of adsorption and desorption. Surface Science, 33 (1), 69-81.

Full Text: S\Sur Sci33, 69.pdf

Abstract: Chemisorption of hydrogen on a platinum-foil has been studied by the flash-filament technique and by the capillary-flow method. Isobars were determined at temperatures between 140 and 600° K and at pressures between 10⁻⁴ and 10⁻⁶ torr. The dependence of the isosteric heat of adsorption E on the coverage σ is given by E = 16.3 − 1.4×10⁻¹⁴σ (kcal/mole) with σ<2.5×10¹⁴ molecules/cm². At higher coverages E reaches values smaller than 5 kcal/mole. Adsorption and desorption at low coverages are second order processes. The initial sticking probability is 4.5×10⁻³. The results are discussed in terms of an atomic and a molecular state of the adsorbed hydrogen.

Procop, M. and Völter, J. (1972), Adsorption von Wasserstoff an platin I. Adsorbierte menge, kinetik der ad- und desorption. Surface Science, 33 (1), 69-81.

Full Text: S\Sur Sci33, 69.pdf

Abstract: Chemisorption of hydrogen on a platinum-foil has been studied by the flash-filament technique and by the capillary-flow method. Isobars were determined at temperatures between 140 and 600° K and at pressures between 10^-4 and 10^-6 torr. The dependence of the isosteric heat of adsorption E on the coverage  is given by E =16.3 -1.4×10^-14  (kcal/mole) with  < 2.5×10¹⁴ molecules/cm². At higher coverages E reaches values smaller than 5 kcal/mole. Adsorption and desorption at low coverages are second order processes. The initial sticking probability is 4.5×10^-3. The results are discussed in terms of an atomic and a molecular state of the adsorbed hydrogen.

Appel, J. (1973), Freundlich’s adsorption isotherm. Surface Science, 39 (1), 237-244.

Full Text: S\Sur Sci39, 237.pdf

Abstract: We present a brief derivation of Freundlich’s adsorption isotherm using straightforeward methods of statistical mechanics. The assumption that the adsorbed atoms move in Morse potential wells of different depths leads to the observed compensation effect in the energy dependence of the occupation probability of surface sites, essential for the understanding of Halsey’s form of the Freundlich isotherm.

Henzler, M. and Töpler, J. (1973), Adsorption of water-vapor on clean cleaved germanium. I. Structural and kinetic-properties. Surface Science, 40 (2), 388-396.

Full Text: S\Sur Sci40, 388.pdf

Abstract: Germanium (111) faces cleaved in UHV have been exposed to water vapor in the pressure range 10^-8 to 1 torr. From LEED observations and Auger electron spectroscopy an adsorption up to one monolayer with two sites per molecule is derived. After adsorption each molecule precludes 3–4 surface atoms from further adsorption. From the disappearance of the superstructure of the clean surface with a fraction of a monolayer it is concluded that each adsorbed molecule converts a patch with about 50–80 surface atoms with respect to superstructure.

King, D.A. (1975), Thermal desorption from metal surfaces: A review. Surface Science, 47 (1), 384-402.

Full Text: S\Sur Sci47, 384.pdf

Abstract: In this review an attempt is made to draw correlations between thermal desorption and structural studies of chemisorption on metal surfaces. Alternative models are discussed for the appearance of multiple peaks and for lineshape analysis in desorption, the first involving multiple binding states and the second lateral interactions within a homogeneous chemisorbed layer. Criteria are discussed for distinguishing between the various possibilities for a particular system, in particular with relation to the adsorption of hydrogen and carbon monoxide on tungsten.

Beck, D.E. and Miyazaki, E. (1975), Molecular adsorption: Analysis of kinetics of adsorption experiment at constant pressure with bulk diffusion. Surface Science, 48 (2), 473-485.

Full Text: S\Sur Sci48, 473.pdf

Abstract: A theoretical analysis of the irreversible adsorption and dissociation of a diatomic gas on the surface of a solid, and the diffusion of the atoms into the substrate is presented. The surface and bulk are treated as separate entities in this analysis. The boundary conditions chosen for the solution of the coupled differential equations are those which correspond to the physical conditions in a ‘dynamic’ adsorption experiment. In analyzing the experimental data for the adsorption of oxygen and nitrogen on titanium, we find that it is nor necessary to invoke diffusion through a compact scale to understand the experimental results.

Baikerikar, K.G. and Hansen, R.S. (1975), Electrocapillary study to test applicability of Flory-Huggins isotherm. Surface Science, 50 (2), 527-540.

Full Text: S\Sur Sci50, 527.pdf

Abstract: The Flory-Huggins isotherm with interaction parameter has been tested using accurate electrocapillary data for four aliphatic compounds at the mercury-electrolytic solution interface. When surface coverages derived by differentiation of surface pressure-activity data were tested in the Flory-Huggins isotherm and when all parameters were freely optimized, the equation fit the data very well in all cases, but the size ratio parameter thus obtained was about 0.5. When parameters of the Flory-Huggins isotherm were fixed by limiting properties of surface pressure-activity data directly (with no differentiations performed), the size parameter was about 1.0. The size parameter expected physically is about 3.0. The Flory-Huggins isotherm with realistic size parameters did not fit the data as well as the simpler Frumkin equation in any of the cases considered. The physical basis underlying both models is weak for interaction parameters as large as encountered in aqueous-organic solute systems.

Jaroniec, M. (1975), Adsorption on heterogeneous surfaces - exponential equation for overall adsorption-isotherm. Surface Science, 50 (2), 553-564.

Full Text: S\Sur Sci50, 553.pdf

Abstract: The adsorption isotherm for heterogeneous surfaces can be very well approximated by the exponential higher degree polynomial of variable In (p/p₀). This equation is obtainable by statistical thermodynamics methods. On some simplifying assumptions one can obtain the Dubinin-Radushkevich and Freundlich adsorption isotherms from the exponential isotherm. The energy distribution function corresponding to the exponential adsorption isotherm can be calculated in the way analogous to that for DR isoterm.

Steinbrüchel, C.O. (1975), On the interpretation of adsorption and desorption kinetics experiments. Surface Science, 51 (2), 539-545.

Full Text: S\Sur Sci51, 539.pdf

Jaroniec, M. and Rudziński, W. (1975), Adsorption of gas mixtures on heterogeneous surfaces: The integral representation for a monolayer total adsorption isotherm. Surface Science, 52 (3), 641-652.

Full Text: S\Sur Sci52, 641.pdf

Abstract: The authors extended the integral equation for a one-component adsorption isotherm on to n-component adsorption from gaseous mixtures. It appears that the n-component adsorption isotherm on heterogeneous surfaces can be presented as a multiple integral. Two methods were used for evaluation of the surface heterogeneity with regard to a gas mixture. The first method is based on the n-dimensional gaussian energy distribution. The second one concerns the extension of our method for studying adsorption systems of high surface heterogeneity. Two-component adsorption systems have been analyzed in details.

Bienfait, M. and Venables, J.A. (1977), Kinetics of adsorption and desorption using Auger electron spectroscopy: Application to xenon covered (0001) graphite. Surface Science,