Strong Lateral Interactions Research Articles

Silica chemically modified with N-benzoyl- N-phenylhydroxylamine in chemisorption of hydrogen and metal ions

New chemically modified silicas – macroporous and pyrogenic – with covalently bonded chelating groups of N-benzoyl- N-phenylhydroxylamine (SiO 2–BPHA) were obtained in three-step surface reaction. From elemental analysis, metal chemisorption and pH titration the concentration of bonded groups was determined as 0.076 and 0.21 mmol g −1 for Silochrome and Aerosil, correspondingly. In both cases about 50% transformation of initial aminopropyl groups to BPHA was achieved. A chemisorption of hydrogen and some metal ions (Fe(III), V(V), Nb(V), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II)) from aqueous and acetonitrile media was investigated. The adequate approximation of interfacial equilibria was only possible if strong lateral interactions between bonded ligands were presumed. From the results of a quantitative physicochemical analysis it was found that dissociation constant of bonded BPHA considerably rose in comparison with the dissociation constants of analogs in solution. Bonded complexes with all studied metals were less stable. Linear correlation between stability of complexes in dioxane–water solution and on the silica surface was found as log β(surf.)=log β(sol.)−2.9. Strong fixation of counter-ions near the surface was concluded from experiments. In aqueous media SiO 2–BPHA demonstrates high selectivity towards Fe(III) and V(V). Linear correlation that was found between concentration of sorbed Fe 3+ and the Kubelka–Munk function for SiO 2–BPHA can be used for ion optical sensoring. Vanadium(V) forms several bonded complexes with different composition instead.

The anodic reactions at mercury electrodes due to cysteine

Abstract The detailed mechanism of anodic reactions of cysteine on mercury electrodes has been ascertained by means of electrocapillary measurements together with d.c. and a.c. polarography and voltammetry. The reactions consist of electro-oxidation of mercury in two separate steps to cystein mercurous and mercuric thiolates respectively which are both strongly adsorbed at the electrode. At low coverages of the electrode by the mercurous product the mercuric thiolate is formed in the potential region of the second step by a non-faradaic surface process of disproportionation of the adsorbed mercurous thiolate; in consequence, only one faradaic step is then observed. The replacement of mercurous by mercuric thiolate at the electrode surface is accompanied by a pronounced change of electrode capacity. The path of the electrode reaction is determined by the form of mercury thiolates in the adsorbed state which depends strongly on the pH of the solution. In the first step in acidic solutions a compact film is formed of perpendicularly oriented mercurous cysteine thiolate molecules held together by strong lateral interaction, in alkaline solutions cysteine forms chelates with S and N atoms binding monomeric monovalent mercury. At positive potentials preceding the mass dissolution of mercury a direct formation of cysteine mercuric thiolate occurs in the solution, followed by its adsorption at the electrode surface.

Packing characteristics of two-component bilayers composed of ester- and ether-linked phospholipids

The miscibility properties of ether- and ester-linked phospholipids in two-component, fully hydrated bilayers have been studied by differential scanning calorimetry (DSC) and Raman spectroscopy. Mixtures of 1,2-di-O-hexadecyl-rac-glycero-3-phosphocholine (DHPC) with 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DHPE) and of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) with 1,2-di-O-hexadecyl-sn-glycero-3-phosphoethanolamine (DHPE) have been investigated. The phase diagram for the DPPC/DHPE mixtures indicates that these two phospholipids are miscible in all proportions in the nonrippled bilayer gel phase. In contrast, the DHPC/DPPE mixtures display two regions of gel phase immiscibility between 10 and 30 mol% DPPE. Raman spectroscopic measurements of DHPC/DPPE mixtures in the C-H stretching mode region suggest that this immiscibility arises from the formation of DHPC-rich interdigitated gel phase domains with strong lateral chain packing interactions at temperatures below 27 degrees C. However, in the absence of interdigitation, our findings, and those of others, lead to the conclusion that the miscibility properties of mixtures of ether- and ester-linked phospholipids are determined by the nature of the phospholipid headgroups and are independent of the character of the hydrocarbon chain linkages. Thus it seems unlikely that the ether linkage has any significant effect on the miscibility properties of phospholipids in biological membranes.

The adsorption of water and amino acids onto hydrophilic and hydrophobic quartz surfaces

The adsorption of (a) serine and leucine and (b) water onto hydrophilic and hydrophobic surfaces was investigated using the radio tracer technique. (a) Films only a fraction of a monolayer (serine 0.45 and leucine 0.30 monolayers as maximum) in thickness were formed. The free energy of adsorption of leucine was found to be 1.147 times greater than that of serine on a hydrophobic surface, and about 1.38 times greater on a hydrophilic surface, i.e. leucine showed a higher affinity of binding onto both surfaces than serine did. Independent of whether serine or leucine is used, the surface concentration is higher on hydrophilic than on hydrophobic surfaces. Furthermore, both amino acids showed a decrease in the adsorption rate at high bulk concentration except for leucine (on a hydrophobic surface) where the surface density increased linearly with bulk concentration. This linear relation was probably an effect of the medium that screened the electrostatic and hydrophobic side-chain interactions. (b) An accelerating rate of adsorption was observed at surface coverage >0.04 of a monolayer indicating strong lateral interactions among adsorbed water molecules. Both isotherms show a high sticking probability coefficient and a saturation level at high bulk concentration. The surface concentration of water (≈ 5–6 monolayers) on a hydrophilic surface was found to be approximately 1.7 times greater than that on a hydrophobic surface.

Chemical and Size Characterization of Layered Lead Iodide Quantum Dots via Optical Spectroscopy and Atomic Force Microscopy

Lead iodide (PbI2) clusters were synthesized from the chemical reaction of NaI (or KI) with Pb(NO3)2 in H2O, D2O, CH3OH, and C3H7OH solvents. The observation of absorption features between the 550 and 350 nm region obtained with an integrating sphere strongly suggests PbI2 quantum dot formation in solution. Comparison of spectra of PbI2 clusters in solution with PbI2 clusters formed by impregnation of PbI2 in four different pore-sized porous silica substrates indicates that the PbI2 cluster size in solution is less than 2.5 nm in the lateral dimension. Atomic force microscopy (AFM) measurements of PbI2 solutions deposited on mica and highly oriented pyrolytic graphite surfaces indicate that the clusters are single layered. The measured height is 1.0 ± 0.1 nm, which is ∼0.3 nm larger than the layer thickness observed for the bulk materials. The swollen layer thickness can be attributed to the intralayer contraction from the strong lateral interaction among PbI2 molecules, which is supported by ab initio calculations. Raman scattering measurements of the LO and TO modes of PbI2 in bulk and in the confined state were also conducted in 50−150 cm-1 region. Three bands observed at 74, 96, and 116 cm-1 for the confined materials are assigned to the TO2, LO2, and LO1 modes, respectively. The relatively small red shift in the LO modes for PbI2 in the porous hosts may be caused by the surface phonon of PbI2 nanoparticles confined in the porous silica.

Macroemulsion Stability: The Oriented Wedge Theory Revisited

The correspondence between the equilibrium phase behavior of oil-water−surfactant mixtures and the macroemulsion type and stability is examined. Both the phase behavior and emulsion stability are argued to be dependent on the bending elasticity of the surfactant monolayer at the oil−water interface. At positive spontaneous curvatures, O/W emulsions are stable; at negative spontaneous curvatures W/O emulsions are stable, whereas, in the balanced state of the surfactant film, an emulsion break usually occurs for a wide variety of systems. To explain the effect of the monolayer bending properties on the macroemulsion stability, the thermally activated rupture of emulsion films is theoretically studied. We consider emulsion films covered by saturated surfactant monolayers, with strong lateral interactions among the adsorbed surfactant molecules. The monolayer at the edge of a nucleation hole in the emulsion film is strongly curved; the bending energy penalty involved leads to a strong dependence of the coalescence barrier on the sign and the absolute value of the monolayer spontaneous curvature. By contrast with earlier hole nucleation theories, the emulsion film thickness is allowed to vary, in order to minimize the free energy of the nucleation hole. At large positive spontaneous curvatures, H0, the oil−water−oil (O/W/O) films are stable, with a coalescence barrier, in a first approximation, proportional to the bending modulus κ. On the other hand, W/O/W films break without a barrier. Conversely, for large negative values of H0, W/O/W films are stable, while O/W/O films break without a barrier. In the vicinity of the balanced state, a very steep change in film stability with H0 is predicted. The model reproduces the macroemulsion stability sequence: O/W emulsion−emulsion breakage−W/O emulsion, observed in polyethoxylated nonionic surfactant−oil−water mixtures with increasing temperature. The macroemulsion break is predicted to occur at the balanced (PIT) point, as has been observed experimentally by Shinoda et al. The hole nucleation in multilamellar-stabilized films is shown to be drastically suppressed, in agreement with the experimental findings of Friberg et al. For rigid surfactant monolayers (κ ∼ 100 kT) and multilamellar-stabilized systems, a region of stable multiple emulsions is predicted, while it is prohibited for flexible (κ ∼1 kT) monolayers. Possible extensions of the model to other systems are discussed.

Electro-oxidation of methanol on Pt(111) in acid solutions: effects of electrolyte anions during electrocatalytic reactions

The electro-oxidation of methanol on a Pt(111) surface in both sulfuric and perchloric acid solutions was investigated by combined apparatus under both ultra-high vacuum and electrochemical environments. In sulfuric acid solution, a strong lateral interaction was observed between adsorbed bisulfate and CO derived from methanol. Coadsorption of CO derived from methanol with bisulfate ion yielded a (√7 × √7)-R19.1°-CO-bisulfate structure. In perchloric acid solution, however, no lateral interaction between adsorbed CO and perchlorate was seen. The difference in reaction rates of methanol oxidation in both solutions was explained by these specific anion adsorption effects.

The domain wall phenomena at the coercive state in KDP crystals

Abstract The dielectric properties of KDP crystals have been known for a long time: high values below the Curie temperature up to the domain freezing. We show the similarity of the domain wall phenomena in the dielectric measurements with natural textures below the transition and in the coercive state during a hysteresis cycle. The properties of these dense domain textures are studied by macroscopic measurements (dielectric, piezoelectric), but also by differential γ ray diffractometry, light and electronic emission, and diffraction of a laser beam. The strong lateral interactions between the domain walls explain the collective processes and the instable situation of the walls themselves.

Stochastic simulations of temperature programmed desorption kinetics

In principle, temperature programmed desorption (TPD) can yield a wealth of information on the rates of surface reactions. In practice, however, it is often difficult or impossible to extract such information from the experimental data. We describe an accurate stochastic modelling technique that facilitates the determination of mechanisms and rate constants from TPD measurements. The model for a particular reaction or process is cast in terms of a detailed mechanism, which can be set up in a variety of ways depending on the primary characteristics of the system under study. Starting from experimental rate constants obtained under limiting conditions, a series of simulations are used to estimate and refine unknown rate constants. Three types of examples are given to illustrate the methodology used. First, simulations of desorption of Xe from Pt(111) are used to show how a very simple system can be modelled. By comparing experimental data and calculations performed with several different mechanisms, we explore the kinetic consequences of various modes of desorption from defect sites. Next, we investigate the competitive desorption and dissociation of CO on W(110). In this case the model successfully reproduces experimental TPD and surface coverage data, allowing experimental rate constants to be optimized. Finally, we show that stochastic simulations can be used to study systems with strong repulsive lateral interactions using a model which explicitly tracks changes in the environment of a desorbing species with temperature and coverage. Previous Monte Carlo simulations of desorption from a square lattice are reproduced using this approach. It is also applied to desorption of CO from Ru(001), yielding simulated TPD spectra in excellent agreement with experiment and allowing the magnitude of repulsive interactions to be estimated. In both the square and hexagonal lattice systems TPD data are simulated with coverage-independent pre-exponential factors: all features of the spectra are attributable to variations in populations of surface species alone. The stochastic method is shown to be valuable as an integral part of an experimental study, allowing detailed models to be proposed and refined, and yielding microscopic data which are amenable to theoretical analysis.

Pattern formation by adsorbates with attractive lateral interactions

A novel theoretical approach for the description of pattern formation by adsorbates with strong lateral interactions, giving rise to a first-order phase transition, is presented. It is based on a continuum mean-field approximation and includes adsorption, desorption as well as surface migration steps, while pairwise interactions are introduced through their strength and effective radius. First applications concern the profiles of interfaces separating domains with differing coverages. Further extension to reacting systems is straightforward.

Unified model for first-order transition and electrical properties of InAs (001) surfaces based on atom-resolved scanning tunneling microscopy imaging

A unified model that explains two differences between InAs and GaAs (001) surfaces, phase transition and electrical properties, is proposed based on atom-resolved images obtained by scanning tunneling microscopy. The annealed InAs surface has much lower density of kinks in the dimer-vacancy rows than the annealed GaAs. This can be the origin both for strong lateral interaction, which causes the first order surface phase transition, and for low surface state density of the InAs (001) surface.

Surface structure transitions on InAs and GaAs (001) surfaces.

Surface structure transitions on InAs and GaAs (001) surfaces are studied by using reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and Monte Carlo simulations. The RHEED study shows that the change in surface structure between As-stabilized (2\ifmmode\times\else\texttimes\fi{}4) and In-stabilized (4\ifmmode\times\else\texttimes\fi{}2) structures on InAs (001) is a discontinuous first-order phase transition with hysteresis, and that the discontinuous transition is not observed on GaAs surfaces. This phenomenon can be explained by a two-dimensional lattice gas model assuming lateral interaction between surface species, and it is suggested that the lateral interaction is stronger with InAs than GaAs. STM observation indicates that this strong lateral interaction between surface species causes a thermally stable dimer vacancy row structure on the InAs (2\ifmmode\times\else\texttimes\fi{}4) surface. RHEED, STM, and SEM observation for misoriented InAs surfaces clarify the role of steps on the phase transition. The metastability of the InAs surface is shown to be reduced by monomolecular steps due to the finite size effects on the phase transition.

Effects of Discrete Protein-Surface Interactions in Scanning Force Microscopy Adhesion Force Measurements.

The potential for measuring specific molecular recognition forces between probe-bound ligands and surface-bound proteins using a scanning force microscope (SFM) has recently gained much attention. Generally, observed discontinuities in the SFM force-displacement curves are attributed to the breaking of discrete, specific affinity bonds. The present study on the molecular recognition system composed of surface-immobilized antifluorescyl IgG molecules and SFM probe-bound fluorescein ligands has demonstrated that similar intermittent discontinuities in the SFM force-displacement curves may in fact be largely due to nonspecific discrete interactions between the protein and the SFM probe. The mechanical behavior of the cantilever-spherical bead system used in this study is discussed, as it appears to cause a false indication of the separation distance between the surface and probe. The strong lateral interactions which result in "stick and slip"-like discontinuities seen in the adhesion curves are likely the result of localized adhesion due to the heterogeneous nature of proteins and the lack of molecular mobility allowed in the experimental system. The effect is magnified with increasing contact time between the protein and probe. Factors which may cause such anomalous behavior in a specific ligand-protein system are discussed in order to avoid misinterpretation of SFM adhesion measurements.

Calorimetric study of water two-dimensionally condensed on the homogeneous surface of a solid

The state of water adsorbed on ZnO, Cr 2O 3 and SrF 2, on which two-dimensional condensation of water occurs, has been studied by a direct calorimetric method. It was found that the differential heat of adsorption exhibits a maximum in the coverage region where a steep increase in the adsorbed amount is observed in the corresponding adsorption isotherm. This suggests the two-dimensional condensation of water due to the strong lateral interaction between water molecules adsorbed on the homogeneous surface in addition to their interaction with the underlying surface. The entropy change for the adsorbed water during the adsorption process, − ΔS ads, can be estimated from the heat and isotherm data, and compared with the theoretical values. As a result, it was revealed that the localized adsorption of water molecules occurs on the homogeneous surfaces of ZnO, Cr 2O 3 and SrF 2 at 301 K. By applying Fowler's equation, which can be applicable to the localized monolayer adsorption on the homogeneous surface with interactions among the adsorbed molecules, to the present systems and by separating the experimental adsorption isotherm into two components, the adsorptions on the heterogeneous surface and on the homogeneous one, the interaction energies for both types of interactions were evaluated; the lateral interaction energies were 8.8, 9.8 and 8.2 kJ mol −1 for ZnO, Cr 2O 3 and SrF 2, and the adsorbate-adsorbent interaction energies were 46, 55 and 58 kJ mol −1, respectively. These results are interpreted in terms of the difference in the structure of these solid surfaces. The adsorbed state of water is also discussed through a dielectric study.

Water adsorption on Pt(111): from isolated molecule to three-dimensional cluster

Water adsorption on Pt(111) at 84 K was investigated by infrared reflection absorption spectroscopy. At a low coverage (θ = 0.13 ML), D 2O adsorption exhibited absorption bands of ν OD at 2475 cm −1 and δ D 2O at 1184 cm −1. The species is assigned to isolated D 2O bound to the surface through the oxygen lone-pair. With increasing coverage (0.13 < θ < 0.67 ML), a strong lateral interaction through hydrogen bonding induces the clustering of water molecules showing an additional absorption of v OD around 2550 cm −1 and an enhancement in the intensity of δ D 2O . Further exposure yields ice growth and also causes a longitudinal interaction between chemisorbed water adjacent to the surface and ice overlayers. Isolated water decreases its fractional coverage because it is included into the hydrogen bonding network of ice overlayers.

Neural network model for the coordinated formation of orientation preference and orientation selectivity maps.

Earlier models for the self-organization of orientation preference and orientation selectivity maps are explicitly designed to reproduce the functional structures observed in cortical tissue. They mostly use formal though biologically motivated implementations and artifical assumptions to achieve this result. In particular, orientation selective cells are usually encoded by doubling the orientation preference angle, which introduces an ad hoc 180\ifmmode^\circ\else\textdegree\fi{} symmetry to the models. This symmetry is then reflected by the emerging \ifmmode\pm\else\textpm\fi{}180\ifmmode^\circ\else\textdegree\fi{} vortices, which parallel physiological findings. In this work a linear feed-forward neural network model is presented that is not designed to reproduce orientation maps but instead is designed to parallel the anatomical architecture of the early visual pathway. The network is trained using a general Hebb-type unsupervised learning rule and uncorrelated white noise as input. Arguments will be given that on average even strong intracortical interactions have only a weak influence on the learning dynamics of the afferent weights. An approximate description of the learning dynamics of these weights is then developed which strongly reduces computational expense without predetermining the receptive field properties, as earlier approaches do. For parameter regimes, where the most stable receptive fields form within the given model network, vortex structures containing singularities and fractures are observed. In addition, for strong lateral interactions, regions of reduced orientation selectivity appear, which coincide with these singularities. Thus, the present model suggests an implicit and biologically plausible coupling mechanism for the coordinated development of orientation preference and orientation selectivity maps.

Molybdenum-oxo Species Deposited on Alumina by Adsorption: III. Advances in the Mechanism of Mo(VI) Deposition

The refinement of the mechanism of Mo(VI) deposition (proposed previously) from aqueous solutions on the γ-alumina surface by investigating critical mechanistic points is the subject of the present work. A mechanistic model involving the adsorption of Mo7O6−24 and MoO2−4 ions on sites created by the protonated surface hydroxyls of γ-alumina in the inner Helmholtz plane (IHP) of the double layer developed between the surface of the γ-alumina particles and the molybdate solutions, as well as the deposition of the MoO2−4 ions through surface reaction with the neutral surface hydroxyls has been developed; ft has been tested over a wide range of impregnation parameters (pH = 8.5-4.1 at 25°C, temperature 25-50°C at pH = 5 and doping of the carrier with various amounts of Na+ and Li+ ions). The testing of the model included the derivation of various equations corresponding to the model deposition equilibria, the calculation of the amount of the deposited Mo, of the difference in the isotherms of the hydrogen adsorption in presence and absence of molybdates, and of the ζ-potential of the γ-alumina particles in the molybdate solution (using an interactive code for the calculation of chemical equilibria in aqueous systems called SURFEQL), and the comparison of these parameters with the corresponding ones determined experimentally. The agreement between the calculated and experimentally determined parameters over a wide range of impregnating conditions allowed us to shed more light on the mechanism of the Mo deposition. It was established that both the adsorption of Mo7O6−24 and MoO2−4 ions and the deposition of MoO2−4 ions by surface reaction with two neutral hydroxyls of the support take place, but the contribution of each of these processes depends on the impregnating conditions. Specifically, in the pH range 8.5-6. 1 the deposition practically occurs through the reaction of MoO2−4 ions with neutral surface hydroxyls of the support resulting in the formation of the surface complex [formula] whereas at pH = 5 the adsorption of Mo7O6−24 and MoO2−4 ions is predominant and at PH = 4.1 the adsorption of Mo7O6−24 ions prevails. Increasing the impregnating temperature, at pH = 5, from 25 to 50°C increases considerably the adsorption of Mo7O6−24 ions and decreases further the deposition of MoO2−4 ions by surface reaction, whereas it does not change considerably the extent of adsorption of MoO2−4 ions. Finally, the doping with Li+ and Na+ ions increases both the extent of adsorption of Mo7O6−24 ions and the extent of MoO2−4 deposition by surface reaction, whereas it does not change considerably the extent of adsorption of MoO2−4 ions. Moreover, it was demonstrated that each protonated surface hydroxyl creates one adsorption site and that strong lateral interactions are exerted between the deposited species, mainly between the adsorbed MoO2−4 and Mo7O6−24 ions, through water molecules located at the IHP. On the other hand, comparison of the adsorption constant with the reaction constant demonstrated that the ionic sorptive band is much stronger than the covalent Al-O-Mo bonds on the above-mentioned surface complex. Finally, the fact that the ratio [MoO2−4]b/[Mo7O6−24]b calculated in the bulk solution was always lower than the ratio [MoO2−4]adsorb+react/[Mo7O6−24]adsorb calculated in the deposited state corroborated the finding reported previously that, concerning deposition, the selectivity of the support surface for the MoO2−4 ions is higher than the selectivity for the Mo7O6−24 ions.

Steady-state kinetics of CO oxidation on Pt: extrapolation from 10 -10 to 1 bar

Under ultra-high vacuum (UHV) conditions, CO oxidation on Pt occurs via the three-step Langmuir-Hinshelwood mechanism including CO adsorption, dissociative oxygen adsorption and reaction between adsorbed CO and O particles resulting in formation of CO 2. Assuming that this mechanism is operating also at high (atmospheric) pressures, we have explored the steady-state reaction kinetics predicted in a wide pressure range by several kinetic models. Focusing on the pressure-gap problem, we have arrived at the following conclusions. (i) If one in simulations employs the kinetic parameters deduced from UHV experiments but ignores the coverage dependence of the CO desorption and CO + O reaction rate constants, the Langmuir-Hinshelwood scheme fails to describe the apparent activation energy and reaction order with respect to CO at high pressures. In addition, the predicted values of the ratio P CO/ P O 2 corresponding to the ignition locus on the stability diagram are in poor agreement with the experiment at high pressures. (ii) The mean-field corrections, taking into account a weak coverage dependence of the rate constant for CO desorption (e.g., UHV data for CO desorption on Pt(111)), are not a sufficient modification to properly describe the reaction kinetics at high pressures. (iii) If one, however, explicitly introduces into the model a strong repulsive nearest-neigbour CO-CO lateral interaction, the predicted results are in reasonable agreement with experiment, both at low and high pressures. In particular, the calculated apparent activation energy and reaction orders are in the same range as the measured ones. The ignition locus on the stability diagram is also predicted at reasonable ratios of P CO/ P O 2.

Step Motion and Structure Transition on InAs and GaAs (001) Surfaces Observed by Scanning Tunneling Microscopy

The step motion and structure transition on InAs and GaAs (001) surfaces are directly observed by scanning tunneling microscopy at high temperatures. A stable (2×4) structure is observed for the InAs surface even at temperatures high enough to cause the motion of monomolecular steps and kinks. At higher temperatures, domains with an In stable (4×2) structure (As desorbed region) are clearly observed surrounded by As stable (2×4) structures. These results differ from those for GaAs surfaces and indicate strong lateral interaction in (2×4) structures on InAs.

Molecular dynamics simulation study of the adsorption of chain alkanes from solution onto graphite

We use the molecular dynamics simulation method to study the adsorption of an n alkane from a benzene solution onto the basal plane of graphite. We show that it is possible to simulate the entire adsorption process, i.e., the diffusion of the alkanes to the surface, the penetration of the highly structured solvent layers near the surface, and the physisorption of the chains on the graphite. Specifically, we consider a solution of C14H30 in benzene confined between two graphite surfaces. The alkane chains are initially dispersed near the center of the slit where the solvent is bulklike. During the simulation, the chains are attracted by the surfaces where they adsorb replacing benzene molecules in the structured liquid near the surfaces. The alkane chains adsorb parallel to the graphite plane assuming predominately stretched conformations without tails extending into the solution. The simulation also shows evidence for the onset of self-organization due to strong lateral interactions between the adsorbed molecules.