X-ray Photoelectron Spectroscopy Line Research Articles

An advance in the use of natural resources: characterisation of the quality of impregnation of bleached alfa pulpboard by unsaturated polyester resin and evaluation of the obtained composite material’s properties

The present work has been conducted in order to investigate the quality of impregnation of unsaturated polyester resin across the bleached alfa pulpboard, and evaluate the potential for the obtained compound to serve a purpose as a useful composite material.The ultra-low-angle Microtomy (ULAM) method was used to study the quality of impregnation of alfa fibres by unsaturated polyester resin. The cross-section through the bleached alfa pulpboard/unsaturated polyester material, which emphasised the impregnation zone, was analysed using X-ray photoelectron spectroscopy (XPS). The profiles obtained by the XPS line scan analysis of the tapered surface show a well-defined impregnation region. The depth of this region has been characterised using two chemical constituent peaks, which showed an approximate depth of impregnation of about 20 to 40 μm, on the basis of COH/COC, components which are exactly complementary to the β-shifted carbon signal, employed as an analogue for the unsaturated polyester. A comparative study was also carried out between the mechanical and tribological properties of the composite material and the pure unsaturated polyester resin, in order to complement the results obtained by surface analysis. The comparison shows better stiffness, tensile strength at break and wears resistance in the reinforced unsaturated polyester resin.The results of this research demonstrate a good quality of impregnation of unsaturated polyester resin across the short alfa fibres which present the matrix and reinforcement of the studied composite material.

Features of the Microstructure and Chemical Compositions of Vanadium-Containing Slags Including Determination of Vanadium Oxidation Degrees.

Metallurgical vanadium-containing converter slag could be used as an alternative vanadium source. The development of a physico-chemical basis for the comprehensive processing of industrial vanadium-containing debris requires information about their elemental composition as well as the oxidation degrees of the elements and forms of compounds in order to solve two key problems: a better utilization of industrial wastes and a lowering of environment impact. This research was aimed at the development of methods to determine the fractions of elements and their oxidation degrees in vanadium-containing industrial debris exemplified by basic oxygen converter vanadium slags. A set of bulk and surface analysis methods (X-ray fluorescence analysis (XRF), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS)) was used for this purpose: based on results of elemental analysis, SEM detects the oxide phases of metals, while an analysis of the XPS lines’ fine structures provides fractions of corresponding elements with definite oxidation degrees. In this way, one can determine the fractions of vanadium in multiple oxidation degrees in slags and can properly select the chemicals and parameters of chemical processes for its fullest extraction.

Regularities of electronic structure transformations in nanomaterials with decreasing their characteristic size

The set of nanomaterials (PbS equiaxial nanocrystals, ZnO films and whiskers, Ag films in TiAlN/Ag nanolaminate multilayer coatings) was studied in a wide range of characteristic sizes. Parameters of their electronic structure as functions of the characteristic size of the nanosystems were analyzed using X-ray photoelectron spectroscopy (XPS) and High resolution electrons energy losses spectroscopy (HREELS) methods. There were determined critical sizes manifesting transition to nanostate. Basing on dependences of donor and acceptor XPS lines size shifts, the two-stage mechanism of electronic structure transformations is proposed: the electronic structure starts to transform below D0 due to surface/volume atoms ratio growth while Dq is associated with preferred role of quantum effects in solids.

Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1–3μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (<10nm) and that the lowest commonly achievable lateral resolution is a number of times higher than the coating thickness (∼2μm), a bulk analysis was achieved with XPS line scans on extended wedge-shaped tapers through the coating. For that purpose a special sample preparation step performed on an ultra-microtome was required prior to analysis. Since a temperature increase leads to a reduction of Cr(VI) we extend our method on samples, which were subjected to different curing temperatures. We show that our proposed approach now allows to determine the elemental and Cr(VI) concentration and distribution inside the coating.

Effects of proton irradiation on single-stranded DNA studied by using X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) has been employed in order to study the effects of proton irradiation on herring sperm single-stranded DNA. Systematic changes of the chemical shifts in the C, N, O, and P XPS line components as functions of the irradiation dose were observed, indicative of the bonding configurations in the DNA system. While the C 1s XPS lines showed weak blueshifts, the N 1s, O 1s, and P 2p XPS lines showed blueshifts with a marked dependence on the irradiation dose in a prominent manner. Our results show that linear energy transfer by charged particles and photons may have distinct molecular-level effects as the C 1s, N 1s, O 1s, and P 2p XPS lines showed redshifts in our previous study of effects of the γ-ray irradiation on the same system.

Variation of Band Gap and Lattice Parameters of β−(AlxGa1−x)2O3 Powder Produced by Solution Combustion Synthesis

Single‐phase monoclinic aluminum–gallium oxide powders, β−(AlxGa1−x)2O3, have been produced by solution combustion synthesis for Al fraction 0 ≤ x &lt; 0.8. α−(AlxGa1−x)2O3 is observed for x = 1, with mixed α + β for x = 0.8. The contraction in lattice parameters and increase in band gap with increasing Al concentration were characterized by X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS), respectively, and are compared with a first‐principles density‐functional theory calculation. A novel filtering procedure is described to reduce the uncertainty involved in measuring band gap using photoemission, and to remove asymmetry in XPS line shapes caused by differential charging of loose powder. The lattice parameters vary linearly with Al fraction, but exhibit a change in slope at x = 0.5 that is attributed to the difference between aluminum occupying tetrahedral and octahedral sites in the monoclinic lattice. The band gap changes linearly with local stoichiometry, including increasing when aluminum content at the surface is enriched relative to the interior, with a range of over 1.8 eV.

A new asymmetric Pseudo‐Voigt function for more efficient fitting of XPS lines

Asymmetric peak profiles for the application in spectroscopy can be obtained in a simple way by substituting the usually constant full width at half maximum parameter in Pseudo-Voigt functions with an energy-dependent expression, for instance of sigmoidal shape. While this approach has been successfully applied to vibrational spectra, we find that the resulting curves are less suitable for least-squares fits of X-ray photoelectron spectroscopy (XPS) data. However, if one additionally allows a variable displacement of the sigmoidal step relative to the peak, excellent fitting results can be obtained. We demonstrate the applicability of our extended approach on several inherently asymmetric XPS lines, i.e. the C 1s signal of graphite and C2H2/Pd(100), the 3d5/2–3d3/2 doublet of palladium, and the 4f7/2–4f5/2 doublet of platinum. Comparison of the corresponding fit results with the results obtained by the application of more elaborate, theory-based line profiles (Doniach-Sunjic and Mahan functions) shows that the modified Pseudo-Voigt function gives practically identical results in terms of peak shape and area, while requiring much less computational effort since no convolution procedures are required for its calculation. Thus, this function is most suitable for application in one of the following situations: (i) the peak shape of a given signal is known but cannot be calculated with ease, and (ii) the theoretical peak shape is not (yet) known, however, one wants to perform a first quantitative screening of the data at issue. Copyright © 2014 John Wiley & Sons, Ltd.

Role of nitrogen on the magnetic properties of MBE grown Mn0.04Ge0.96 films

We report the role of nitrogen on the distribution of Mn atoms and ferromagnetism in Mn0.04Ge0.96 films. High quality Mn0.04Ge0.96 films are obtained by sequential evaporation of stacked Mn and Ge layers on Si (100) substrate in N2 environment. The experimental results reveal that the films grown under 5×10−5Torr N2 partial pressure exhibit improved crystallinity and magnetic properties when compared to vacuum deposited films. Correlating the results of electron spin resonance (ESR) and x-ray photoelectron spectroscopy (XPS) studies with magnetic measurements, we have found that introduction of N2 during growth effects the distribution of Mn atoms in Ge. Incorporation of nitrogen into the films and degree of magnetic ordering was obtained from XPS spectra and line shape analysis of ESR spectra. In the presence of nitrogen, enhancement in Curie temperature is associated with the increase in the number of active Mn atoms, however promoted Mn diffusion leads to formation of Mn5Ge3 clusters.

A new asymmetric Pseudo‐Voigt function for more efficient fitting of XPS lines

Asymmetric peak profiles for the application in spectroscopy can be obtained in a simple way by substituting the usually constant full width at half maximum parameter in Pseudo‐Voigt functions with an energy‐dependent expression, for instance of sigmoidal shape. While this approach has been successfully applied to vibrational spectra, we find that the resulting curves are less suitable for least‐squares fits of X‐ray photoelectron spectroscopy (XPS) data. However, if one additionally allows a variable displacement of the sigmoidal step relative to the peak, excellent fitting results can be obtained. We demonstrate the applicability of our extended approach on several inherently asymmetric XPS lines, i.e. the C 1s signal of graphite and C2H2/Pd(100), the 3d5/2–3d3/2 doublet of palladium, and the 4f7/2–4f5/2 doublet of platinum. Comparison of the corresponding fit results with the results obtained by the application of more elaborate, theory‐based line profiles (Doniach‐Šunjić and Mahan functions) shows that the modified Pseudo‐Voigt function gives practically identical results in terms of peak shape and area, while requiring much less computational effort since no convolution procedures are required for its calculation. Thus, this function is most suitable for application in one of the following situations: (i) the peak shape of a given signal is known but cannot be calculated with ease, and (ii) the theoretical peak shape is not (yet) known, however, one wants to perform a first quantitative screening of the data at issue. Copyright © 2014 John Wiley &amp; Sons, Ltd.

High Resolution Core- and Valence-Level XPS Studies of the Properties (Structural, Chemical and Bonding) of Silicate Minerals and Glasses

Core-level and valence-level X-ray Photoelectron Spectroscopy (XPS), developed in the late 1950’s and 1960’s by Siegbahn and coworkers (Siegbahn et al. 1969; Carlson 1975; Barr 1993; Fadley 2010) has become an invaluable tool over the last 40 years for studying mainly the surface properties and reactivity of a wide range of minerals, predominantly oxides (for reviews, see: Heinrich and Cox 1994; Chambers 2000; Salmeron and Schlogl 2008, and references in Bancroft et al. 2009; Newburg et al. 2011), sulfides (for reviews, see Hochella 1988; Bancroft and Hyland 1990; Nesbitt 2002; Murphy and Strongin 2009) and silicates (for a review see Hochella 1988; references in Biino and Groning 1998; Oelkers 2001; Zakaznova-Herzog et al. 2008). The large majority of these studies have focused on the first few surface monolayers of the minerals because of the surface sensitivity of the technique (~2–20 monolayers for photon energies of ≤ 1486 eV (Hochella 1988; Nesbitt 2002), and in many such cases, XPS has become the technique of choice for surface studies. Silicate XPS studies generally have focused on three surface applications outlined by Hochella (1988): (1) studies of the oxidation state of near surface atoms (e.g., Fe); (2) studies of sorption reactions on mineral surfaces; and (3) studies of the alteration and weathering of mineral surfaces. Fewer reports have focused on the fourth application of Hochella (1988), the study of the bulk atomic structure and chemical state properties of minerals and glasses. This is surprising perhaps, because the large majority (usually >90 %) of XPS line intensities comes from the bulk mineral in XPS studies using the typical laboratory Al K α X-ray sources (1486.6 eV). To emphasize this point, the surface S 2 p peaks from the …

Core Level Data of Ionic Liquids: Monitoring Charging by In Situ Electrochemical X-ray Photoelectron Spectroscopy

Ionic liquids (ILs) are reported to provide large electrochemical stabilitywindows(4‐6V)makingthemattractiveelectrolytesforelectrochemical processes and applications. 1 Most ILs are also ultra high vacuum (UHV) compatible. Therefore, these compounds allow for application of analytical tools to, for instance, study electrochemical processes in situ in the UHV. 2 From fundamental X-ray photoelectron spectroscopy (XPS) studies of ILs, sample charging is known to be a major challenge. 3,4 Recently, we showed that ILs prepared on an activated carbon (AC) support show significantly improved XPS data with respect to charging. This result suggested that such a preparation method may provide a straightforward opportunity for the determination of reliable binding energies (BE) of ILs in this research field. 5 The lack of charging observed on the AC support was referred to the high surface area and, therefore, high double layer capacitance of AC when compared to common supports such as metal foils. In the present letter we further investigate charging using our recently designed in situ electrochemical XPS cell. 6 This setup allows recording shifts of core level spectra of the IL and measuring the potential of the WE simultaneously. In particular, the OCP can be measured as a function of the irradiation time. In agreement with the fundamental concept of electrochemically shifted binding energies, 6 the XPS lines shift by −1.0 eV/V with the X-ray induced OCP shift. Furthermore, the in situ investigations confirm that the lack of charging previously observed on AC support can indeed be explained by the high double layer capacitance of the support compensating the X-ray induced OCP and BE shift observed on smooth substrates.

High resolution X-ray Photoelectron Spectroscopy (XPS) study of K2O–SiO2 glasses: Evidence for three types of O and at least two types of Si

High resolution O 1s, K 2p and Si 2p XPS Spectra were collected for a series of potassium silicate glasses ranging in composition from 10mol% to 35mol% K2O. The mole fraction of bridging oxygen (BO) has been accurately evaluated from the O 1s spectra. BO mole fractions of K-silicate glasses were calculated from Q-species distributions previously reported by 29Si MAS NMR data. The mole fractions of BO are identical for the two techniques (within experimental error) in glasses containing 13mol% to 25mol% K2O but in the compositional range between 25mol% and 35mol% BO mole fractions obtained by XPS are slightly greater than values derived from NMR data. The slight discrepancies between the two techniques at higher K2O content have not been resolved. The experimental data between 13mol% and 25mol% K2O indicate the presence of a third type of oxygen, O2−, in these glasses. A thermodynamic analysis indicates O2− is present at a few mol% in the glasses of low K2O content, but increases monotonically with increased K2O content.The O 1s XPS line widths for the BO peaks are highly variable. The variation in line widths may result from two types of BO contributing to the BO peak. As in the Na2O–SiO2 glass system, one type probably bridges two Si atoms (SiOSi) and the second type is O bonded to two Si atoms and one K atom.The Si 2p XPS spectra are distinctly non-symmetric, with low binding energy shoulders commonly present on the major peak, suggesting two contributions to the Si 2p signal. There is a strong correlation of Si 2p XPS peak and shoulder intensities with the abundances of the Q4 and Q3 species in glasses of the same composition suggesting that, with additional resolution, XPS may be capable of resolving individual Q-species in this system.

Effect of Radiation Defects on the Electronic Structure of Zircon by X-Ray Photoelectron Spectroscopy Data

X-Ray photoelectron spectroscopy (XPS) is used to study the electronic structure of radiation damaged samples of ZrSiO4 zircon mineral at early and middle stages of its radiation destruction. The effects of radiation induced atomic disordering are found to be most distinctly manifested in the spectra of O1s states and to a smaller extent in the spectra of Si2p states, and also in the zircon valence band. Based on the quantum chemical calculation results the conclusion is drawn that the observed changes in XPS lines are caused by the formation of oxygen vacancy defects and an increase in the covalency of interatomic bonds near oxygen vacancies. For zircon samples with a low/moderate degree of radiation damage these changes reflect the initial stage of the polymerization of the ZrSiO4 structure due to the formation of Si—O—Si chain fragments.

X-ray induced damage in DNA monitored by X-ray photoelectron spectroscopy

In this work, the chemical changes in calf thymus DNA samples were analyzed by X-ray photoelectron spectroscopy (XPS). The DNA samples were irradiated for over 5 h and spectra were taken repeatedly every 30 min. In this approach the X-ray beam both damages and probes the samples. In most cases, XPS spectra have complex shapes due to contributions of C, N, and O atoms bonded at several different sites. We show that from a comparative analysis of the modification in XPS line shapes of the C 1s, O 1s, N 1s, and P 2p peaks, one can gain insight into a number of reaction pathways leading to radiation damage to DNA.

Characterization of Langmuir−Blodgett Film Using Differential Charging in X-ray Photoelectron Spectroscopy

Differential charging is often regarded as a problem in X-ray photoelectron spectroscopy (XPS) studies, especially for insulating or partially conducting samples. Neutralization techniques have been developed to circumvent this effect. Instead of neutralizing the positive charge, which is often the technique to obtain good quality data, it is possible to exploit this phenomenon to get useful information about the sample. An attempt is made here to use this differential charging to study the mono- and multilayer Langmuir-Blodgett (LB) films of cadmium arachidate on silicon substrate. The surface potential was probed by measuring XPS line shift with respect to their neutral position and was found to have correlation with the thickness of the films. No differential charging was observed in the monolayer LB film where there was only one layer of cadmium headgroup. Significant differential charging was observed for multilayer films, the total charging as well as the differential charging in these films increase with increasing number of layers. Angle-resolved XPS measurements were performed to obtain additional information about the structure of the films. Charging of the upper layer of the films close to the vacuum interface was found to be less compared to that of the interior. The discrete cadmium layers were found to be more differentially charged compared to the continuous hydrocarbon stacks in the multilayer LB films. Charging of the discrete cadmium layers has been utilized to obtain quantitative information of the multilayer LB films.

Characterization of hydroxyl groups on water-reactedSi(001)−2×1using synchrotron radiation O1score-level spectroscopies and core-excited state density-functional calculations

The system constituted by the $\mathrm{Si}(001)\text{\ensuremath{-}}2\ifmmode\times\else\texttimes\fi{}1$ surface exposed to water molecules at room temperature has been chosen to single out the electron structure of the hydroxyl SiOH, a surface species playing an important role in many technologically relevant processes. We confront here original core-electron spectroscopy density functional theory (DFT) calculations to synchrotron radiation O $1s$ x-ray photoelectron spectroscopy (XPS) and (polarization-dependent) near-edge x-ray absorption spectroscopy (NEXAFS) data. Using clusters to mimic the silicon surface, various SiOH environments (unpaired and paired hydroxyls) have been examined. The impact of the hydrogen bond on the calculated core-ionized and/or neutral core-excited states is examined, and compared to the limit case of the water dimer. The theoretical approach enables us to label the main experimental NEXAFS transitions and to interpret their polarization-dependent dichroism. As water dissociation on the surface can go beyond the formation of hydroxyls, the DFT electron structure of bridging oxygens (SiOSi) is calculated. It is predicted that the XPS line associated to the latter species is shifted by $0.5--1.0\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ to lower binding energy with respect to that of the hydroxyls. Then, on this basis, the reconstruction of the experimental O $1s$ XPS spectrum can provide the relative distribution of hydroxyls and of the bridging oxygens (a minority species). The present work paves the way for future spectroscopic works examining the bonding and reactiveness of hydroxyls with other molecular species.

Titania Supported Bimetallic Transition Metal Oxides for Low-Temperature SCR of NO with NH3

High surface area titania supported Mn-Cu and Mn-Cr bimetallic oxides were prepared by wet impregnation method using their nitrate salts. The catalytic activity of these materials was evaluated for selective catalytic reduction (SCR) of NO with NH 3 in the presence of excess oxygen at low temperatures (373-523 K). The surface and bulk properties of the catalysts were examined using X-ray diffraction, BET-surface area, FT-IR, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) techniques. X-ray diffraction (XRD) studies revealed the formation of definite crystalline compounds MnCrO 3 and CrMn 1.5 O 4 for Mn-Cr/TiO 2 samples and Cu 1.4 Mn 1.6 O 4 and Cu 1.5 Mn 1.5 O 4 for Mn-Cu/TiO 2 samples. The specific surface areas of the prepared catalysts were significantly lower than the pure TiO 2 support. The FT-IR studies indicate that the acidic strength of these catalysts was higher than the corresponding single oxide catalysts. TPR studies suggest that the shift in the reduction peak position toward higher temperatures in bimetallic oxides is probably due to the formation of binary or ternary metal oxide phases, as observed from XRD study. The XPS peak intensities and the corresponding binding energies indicate that the surface concentration of Mn is lower than either Cu or Cr at equal metal loadings. A slight shift of the Mn 2p XPS line toward higher binding energies (642.1 eV) was observed in the case of Mn-Cu/TiO 2 and Mn-Cr/TiO 2 catalysts. This is due to the formation of stoichiometric mixed oxide phases between promoted metal oxides, which was observed in the XRD study. The core level binding energy values indicate that the manganese is present as Mn(IV) in both the catalysts. The activity results of these catalysts were compared with their corresponding single oxide catalysts.

Electronic structure of Ti metal and TiO 2 powder studied by hard and soft (Cu Kα 1 and Al Kα1) X-ray photoelectron and Auger spectroscopy

High-energy X-ray photoelectron spectroscopy (XPS) is of particular importance for minimizing the effects of surface contamination by increasing photoelectron escape depths. In this study high-resolution high-energy Cu Kα 1 and soft Al Kα 1 XPS and Auger electron spectroscopy were used to compare the electronic structure of Ti in TiO 2 powder and Ti metal. The Ti 1s in TiO 2 XPS line is narrower and more symmetric than in Ti metal. A comparison of the relative intensities of the L 23M 23M 45 and L 23M 23M 23 Auger transitions in Ti metal and TiO 2 is consistent with the expected transfer of Ti 3d electrons away from the Ti site in the oxide. The satellites accompanying the Ti 1s XPS line excited by Cu Kα 1 X-rays occur at the same energies as the satellites accompanying the Ti 2s and 2p XPS lines excited by Al Kα 1 X-rays indicating that they do not depend on the core-level, the experimental resolution or inelastic scattering processes.

Monolayer vs. multilayer self-assembled alkylphosphonate films: X-ray photoelectron spectroscopy studies

Combining functional organic self-assembled monolayers (SAMs) with conventional semiconductor materials is a key step in the development of integrated electronics-based devices. T-BAG (Tethering by Aggregation and Growth) has been shown to be a simple and reliable method to grow SAMs of alkylphosphonates on oxide surfaces. However, distinguishing SAMs from ultra-thin multilayers is a challenge for most conventional surface characterization techniques. Self-assembled films of octadecylphosphonic acid (ODPA) were deposited on oxide-covered silicon coupons, converted to the corresponding phosphonates, and characterized by high resolution angularly resolved X-ray photoelectron spectroscopy (XPS). It was our goal to distinguish among different bonding configurations for phosphorous in the phosphonate head groups, namely, mono-dentate, bi-dentate or tri-dentate interactions with the oxide surface, as well as to assess quantitatively the near-surface layer composition. We also present an innovative method that allows us to distinguish between monolayer and multilayer films of ODPA on silicon oxide surfaces. This method is based on differential surface charging effects in XPS. It was found that variation in the ODPA film thickness causes differential responses of various spectral characteristics to an electrical bias applied to the sample during XPS measurements. Both positive and negative applied biases were found to affect the carbon core-level (C1s) line-shape and intensity in the case of the multilayer ODPA film, whereas line-shapes and intensities of all XPS lines measured for the monolayer film were unaffected by the application of a dc bias in the ±30 V range.

Experimental and theoretical study of the adsorption of fumaramide [2]rotaxane on Au(111) and Ag(111) surfaces

Thin films of fumaramide [2]rotaxane, a mechanically interlocked molecule composed of a macrocycle and a thread in a "bead and thread" configuration, were prepared by vapor deposition on both Ag(111) and Au(111) substrates. X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy were used to characterize monolayer and bulklike multilayer films. XPS determination of the relative amounts of carbon, nitrogen, and oxygen indicates that the molecule adsorbs intact. On both metal surfaces, molecules in the first adsorbed layer show an additional component in the C 1s XPS line attributed to chemisorption via amide groups. Molecular-dynamics simulation indicates that the molecule orients two of its eight phenyl rings, one from the macrocycle and one from the thread, in a parallel bonding geometry with respect to the metal surfaces, leaving three amide groups very close to the substrate. In the case of fumaramide [2]rotaxane adsorption on Au(111), the presence of certain out-of-plane phenyl ring and Au-O vibrational modes points to such bonding and a preferential molecular orientation. The theoretical and experimental results imply that the three-dimensional intermolecular configuration permits chemisorption at low coverage to be driven by interactions between the three amide functions of fumaramide [2]rotaxane and the Ag(111) or Au(111) surface.