The oxygen low-pressure plasma treatment of polymer surfaces promotes their adhesion to metals. It is well known that such treatment results in the formation of a wide variety of O functional groups, polymer degradation and crosslinking. Only a few watts and short exposure times (0.1 to 2 s) provide the optimum in functionalization and in preserving the original polymer structure. Therefore, these are the best conditions for maximum adhesion in many metal-polymer systems. Carbonate, ester, and aromatic groups are rapidly split by an oxygen plasma treatment leading to scissions of polymer backbones and loss in molecular weight. The formation of macrocycles and a large number of C=C bonds in a region of around 4 nm in depth is of interest. Crosslinking of polymers due to oxygen plasma exposure is a very important process. It can be verified by Thermal Field Flow Fractionation (ThFFF) by which gel particle concentration and particle diameters can be measured. The investigated polymers could be divided into different types of degradation behaviour on exposure to an oxygen plasma. Chromium or potassium strongly react with functional groups at polymer surfaces and may cause complete disordering of macromolecules in a ≈ 2 nm thick near-surface layer. Cr complexes formed by dπ-pπ interactions and the formation of carbide-like species are identified. Generally, a redox reaction at metal-polymer interfaces is accompanied by a modification of the interface free energies. The redox potential of the metal component (K>Al>Cr; Cu=electropositive) is the key parameter here. The oxygen plasma pretreatment was applied to a C18 Self-Assembled Monolayer followed by Cr deposition. A redox reaction between Cr and plasma introduced C=O groups was also observed. In order to analyse treated polymer surfaces and interfaces the well-established X-ray Photoelectron Spectroscopy (XPS) and also X-ray Absorption Spectroscopy (XAS) were employed. Furthermore, molecular weight distributions of thin polymer layers were measured by the chromatographic methods: Size Exclusion Chromatography (SEC) and Thermal Field Flow Fractionation (ThFFF) and also by mass spectrometry (Matrix-Assisted Laser Desorption Ionization Mass Spectrometry, MALDI-MS).

Biosensors are of essential importance in medical and biological diagnostics. Often, they are produced using silane chemistry on glass or silicon oxide surfaces. However, controlling that silane chemistry is challenging. Here, we present an alternative strategy to form functional organic layers and biosensors on silicon nitride (Si3N4). H-terminated Si3N4 films are used to generate reactive azide groups by various azidation methods. Biomolecular probes can then be immobilized using click chemistry reactions with the azide groups and due to its high sensitivity in XPS a fluorine-substituted test alkyne was utilized to optimize click chemistry conditions. After that a biotinylated alkyne was clicked to Si3N4 surfaces followed by immobilization of streptavidin as analyte in a model assay. The functionalized surfaces were thoroughly characterized by surface chemical analysis using X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy.

Covalent modification of surfaces with carbohydrates (glycans) is a prerequisite for a variety of glycomics-based biomedical applications, including functional biomaterials, carbohydrate-arrays, and glycan-based biosensors. The chemistry of glycan immobilization plays an essential role in the bioavailability and function of surface bound carbohydrate moieties. For biomedical applications the stability over time (shelf life) of glycan arrays is a crucial factor. Herein we report on approaches for surface and interface characterization relevant to the needs of production of glycan microarrays which were tested using model carbohydrate surfaces. For detailed characterization of glycan model surfaces we used a combination of X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS) and ToF SIMS which are complementary techniques of surface chemical analysis. Links to fluorescence spectroscopy often used for characterization in the microarray community were established as well. In detail, amine-reactive silicon oxide and glass surfaces were used for anchoring oligosaccharides with an amino linker. The amount of surface bound carbohydrates was estimated by X-ray photoelectron spectroscopy (XPS). Glycan immobilization was investigated using lectins, which are glycan-binding molecules. A shelf life study of model glycan microarrays on epoxy-coated glass surfaces was done over a period of 160 days under different storage conditions utilizing fluorescence, ToF-SIMS and XPS analysis. It was shown that glycan activity of the models used can be maintained at least for half a year of storage at 4 degrees C.

In this study, a new direct functionalization method of silicon nitride (Si3N4) using azidation and click chemistry is presented. First, amino groups (NHx) were created on a Si3N4 substrate by fluoride etching. These NHx‐terminated Si3N4 surfaces were analyzed by chemical derivatization X‐ray photoelectron spectroscopy with 4‐trifluoromethylbenzaldehyde, and a derivatization yield of 20% was concluded. In the second step, freshly prepared NHx surfaces were transformed into azides, which were used immediately in a click reaction with halogenated alkynes. The presented combination of amination, azidation, and click reaction is a promising alternative for common silane‐based Si3N4 functionalization methods. Copyright © 2016 John Wiley & Sons, Ltd.

In this work, fullerene has been functionalized with cyanuric chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction.

The preparation and characterization of a Titanium dioxide (TiO2) by a simple, cost effective, facile and eco-friendly green synthesis method using Peltophorum pterocarpum plant extract is presented. The green synthesized nanoparticles were characterized using X-ray diffraction (XRD), Raman spectroscopy, High-resolution transmission electron microscopy (HR-TEM) and X-ray absorption near edge spectroscopy (XANES). XRD results show that the prepared TiO2 NPs were significantly crystalline with various percentages of anatase and rutile phases. The nanoparticles were found to have different diameters ranging from 20 to 80nm. No evidence of any intermediate or different TiO2 phases were found in XANES measurements performed at the Ti K- and L-edge. It is shown that the TiO2 NPs with high uniformity, high surface area and minimum aggregation can be prepared with relative ease and the desired anatase: rutile phase ratio can be obtained by controlling the experimental conditions.

Research on carbohydrate‐based interactions with proteins, nucleic acids, or antibodies has gained increased interest in the last years especially in clinical diagnosis or drug development. The efficiency of diagnostic interfaces depends upon the number of probe molecules, e.g., carbohydrates. The control of surface parameters as density and distribution of immobilized carbohydrates is essential for a reliable interaction with protein analytes. A controlled production of biomolecular interfaces can be reached by a stepwise quality control during buildup of these biointerfaces.Here, ß‐amino‐cyclodextrin molecules were attached to amine‐reactive silicon oxide surfaces via click chemistry to construct a model biosensor surface. The amount of surface bound carbohydrates was determined indirectly after chemical derivatization with 4‐(trifluoromethyl)‐benzylamine (TFMBA). Moreover, these surfaces were used to form host–guest complexes of ferrocene (guest) and β‐cyclodextrin (host) moieties to mimic the target binding (sensing) of the model biosensor. Surface chemical analysis of all steps during biosensor construction was performed using X‐ray photoelectron spectroscopy and near‐edge X‐ray absorption fine structure spectroscopy. Our approach widens the possibilities to generate switchable surfaces based on ß‐cyclodextrin surfaces for biosensor applications. Copyright © 2016 John Wiley & Sons, Ltd.

Organosilanes are used routinely to functionalize various support materials for further modifications. Nevertheless, reliable quantitative information about surface functional group densities after layer formation is rarely available. Here, we present the analysis of thin organic nanolayers made from nitrogen containing silane molecules on naturally oxidized silicon wafers with reference-free total reflection X-ray fluorescence (TXR.F) and X-ray photoelectron spectroscopy (XPS). An areic density of 2-4 silane molecules per nm(2) was calculated from the layer's nitrogen mass deposition per area unit obtained by reference-free TXRF. Complementary energy and angle-resolved XPS (ER/AR-XPS) in the Si 2p core-level region was used to analyze the outermost surface region of the organic (silane layer)-inorganic (silicon wafer) interface. Different coexisting silicon species as silicon, native silicon oxide, and silane were identified and quantified. As a result of the presented proof-of-concept, absolute and traceable values for the areic density of silanes containing nitrogen as intrinsic marker are obtained by calibration of the XPS methods with reference-free TXRF. Furthermore, ER/AR-XPS is shown to facilitate the determination of areic densities in (mono)layers made from silanes having no heteroatomic marker other than silicon. After calibration with reference-free TXRF, these areic densities of silane molecules can be determined when using the XPS component intensity of the silane's silicon atom.

A toluene solution of 4,4′‐methylenebis(2,6‐diethylaniline) was spin coated on Si wafers. The samples were derivatized with pentafluorobenzaldehyde (PFB) in order to determine the primary amino groups on the surface. XPS C 1s and N 1s and C and N K‐edge NEXAFS of underivatized and derivatized films were carefully analyzed. The result was that after 10 min of exposure the gas–surface reaction was already completed. A reasonable derivatization reaction yield in the order of 90% is derived from the experiments. This number correlates well to a reaction yield obtained by a wet chemical approach. Copyright © 2008 John Wiley & Sons, Ltd.

The formation of plasma-polymerized materials made from organic molecules is a technologically attractive way to obtain films with unique properties for life science applications. Surface properties like bio-compatibility, wettability, etc., can be adjusted by tailoring the chemical functionalization. It is well known that after deposition these films undergo post-plasma reactions, especially when they are exposed to ambient atmosphere. Most often, in applications these films are not used immediately after their deposition – they are usually stored for a certain time. Therefore there is a need for a development of analytical procedures enabling studies of ageing phenomena of plasma chemically deposited films. With the help of these studies a better understanding of basic post-plasma reaction phenomena as well as relevant empiric information for practical applications can be obtained. However, a detailed chemical characterization of plasma chemically deposited films is a great challenge for the analysts because of the co-existence of a number of different chemical species. We investigated r.f. plasma-polymerized organic films by using photoelectron spectroscopy for chemical analysis (ESCA), spectroscopy of the near edge X-ray absorption fine structures (NEXAFS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Ethylene, styrene, allyl alcohol and allyl amine were used as monomers. A dedicated plasma preparation chamber was designed and added to the main analysis chamber of the respective spectrometer. This approach offers the possibility to study plasma-polymerized films in situ and, subsequently, the influence of post-plasma reactions. The important effect of air exposure of the film, in terms of plasma technology denominated as “ageing”, can be studied subsequentially step by step by this unique approach.

The formation of plasma‐deposited materials made from organic molecules is a technologically attractive way to obtain films with unique properties, e.g. adhesion, wettability, conductivity or selected chemical functionalization. A detailed chemical characterization of these films is a great challenge for the analyst because of the co‐existence of a large number of chemical species in plasma‐deposited films. We investigated these types of organic films using photoelectron spectroscopy for chemical analysis (ESCA, XPS), near edge X‐ray absorption fine structure (NEXAFS) spectroscopy at synchrotron radiation source BESSY II and time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS). A dedicated plasma preparation chamber was designed and added to the main analysis chamber of the respective spectrometers. This approach offers the possibility of studying plasma‐deposited films without exposure to air before analysis (often called in‐situ analysis) and the influence of post‐plasma reactions, i.e. the ageing process. The present investigations are aimed at finding correlations between basic chemical properties of the deposited films and the plasma deposition parameters, e.g. duty cycle in pulsed plasmas and the power of discharge. Copyright © 2006 John Wiley & Sons, Ltd.

Plasma deposited allylamine films were studied by "in situ" ToF-SSIMS, XPS and NEXAFS Spectroscopy before exposure to ambient air. The influence of external, plasma power, and plasma parameters such as duty cycle. monomer flow rate on (i) unsaturation, (ii) branching and cross-linking, (iii) nitrogen surface concentration and (iv) retention of amino groups was investigated. Harder plasma conditions, which can be obtained when high duty cycles, high plasma power, and low monomer flow rates are employed, increase the unsaturated, branched and crosslinked character of the plasma deposited films, while the Surface concentration of N as well as the retention of the monomer's amino group decrease. As proven by NEXAFS findings and cross-checked by ToF-SSIMS results, the allylamine monomer's primary amino groups are partially transformed into other nitrogen functionalities during, its plasma polymerization. Amongst them imines and nitrites are the conversion products with the highest probabilities of formation. Another conversion channel is the formation of nitrogen species not participating in the film growth. This is the reason for an increased N loss in plasma deposited allylamine films as observed independently by XPS and ToF-SSIMS when the plasma parameters are changed from mild to hard.

The dismutation of CCl(2)F(2) was used to probe the effect of halogenation of chromia by Cl/F exchange reactions to find out the difference between the halogenated inactive and active catalysts. The heterogeneous reactions were performed in a continuous flow Ni reactor and also under simulated reaction conditions in a reactor where after the reaction X-ray photoelectron spectroscopy (XPS) and X-ray excited Auger electron spectroscopy (XAES) analyses are possible without air exposure of the catalyst, i.e., under so-called "in situ" conditions. The Cr(III) 2p XP spectra, which revealed multiplet splitting features and satellite emission, were used for chemical analysis by using a simple evaluation procedure which neglects this inherent complexity. Chemical analysis was also applied by using chemical state plots for Cr 3s in order to cross-check Cr 2p related results. Both ex and in situ XPS show that as soon as Cr(2)O(3) is exposed to CCl(2)F(2) at 390 degrees C fluorination as well as chlorination takes place at the catalyst surface. When the XPS surface composition reaches approximately 4 at. % fluorination and 6 at. % chlorination, maximum catalytic activity was obtained. Application of longer reaction times did not change significantly the obtained surface composition of the activated chromia. The fluorination and chlorination of chromia was further investigated by various HF and HCl treatments. The activated chromia samples and the Cr(2)O(3), Cr(OH)(3), CrF(2)OH, CrF(3) x H(2)O, alpha-CrF(3), beta-CrF(3), and CrCl(3) reference samples with well-known chemical structures were also characterized by X-ray absorption near edge structure (XANES), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), pyridine-FTIR, wet chemical (F and Cl) analysis, X-ray powder diffraction (XRD), and surface area (BET) analysis. The results suggest that the formation of chromium oxide chloride fluoride species, e.g., chromium oxide halides, at the surface is sufficient to provide catalytic activity. The presence of any CrF(3) and/or CrCl(3) phases on the activated chromia samples was not found.

Plasma polymerised films of acrylic acid, allyl alcohol and allyl amine were prepared and studied by XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy). The influence of external plasma parameters on certain chemical aspects of the films was investigated. The use of XPS and NEXAFS (near edge X-ray absorption fine structure) as complimentary tools in the surface characterisation of thin films has been highlighted. Certain chemical aspects of the plasma polymerised films such as presence of ROCO in the case of plasma polymerised acrylic acid films, presence of RCO and RC–OR bonds in case of plasma polymerised allyl alcohol films and presence of RCN and C≡N in case of plasma polymerised allyl amine films were studied. The concentration of ROCO species was found to decrease with increase in r.f. duty cycle in the case of plasma polymerised acrylic acid films. In case of plasma polymerised allyl alcohol films there is a decrease in the concentration of RCO species and increase in the concentration of RC–OR species at higher pressures, while in the case of plasma polymerised allyl amine films the concentration of RCN and C≡N increases at higher powers, with an increase in C≡N more pronounced at higher powers.

Cr–N film coatings were prepared by magnetron sputter deposition at different nitrogen partial pressures. The film characterisation by XRD and DTG gives average bulk compositions of Cr2N and CrN for the coatings. Highly sensitive XPS investigations were performed and the chemical and phase compositions of a film surface range of about 10 nm thickness was estimated quantitatively from the deconvoluted peak intensities. It is demonstrated that the composition of the surface of chromium nitride thin films differs from the core and is more complex in constitution. Not only chromium nitrides (Cr2N and CrN) but also chromium oxynitrides and chromium oxides (CrOx and CrOxHy) were detected. Metallic chromium was also found in films prepared at higher nitrogen flow. The concentration of the estimated phases shows dependence on film preparation and additional heat treatment.

By using modern XPS systems it is possible to obtain spectra with well-resolved spin orbit, multiplet and field splitting even with powder samples mounted using adhesive tape. Measurement of Cr2O3 powder with the latest generation of XPS spectrometers, which are able to analyse non-conductive powders with ultimate energy resolution, revealed multiplet splitting features and satellite emission in the Cr 2p spectrum. Therefore, peak-fit analysis of Cr 2p XPS spectra of Cr(III) compounds requires a more appropriate approach and common practice has to be reconsidered. One possible way to analyse this spectrum is proposed, based on the experimental and theoretical work of other authors. Copyright (C) 2004 John Wiley Sons, Ltd.

Several approaches were investigated to produce monosort functionalized polymer surfaces with a high density and homogeneity of functional groups: (i) Plasma oxidation followed by wet-chemical reduction, (ii) formation of radicals and grafting on of functional group carrying molecules, (iii) plasma bromination followed by (iv) Williamson or Gabriel-like synthesis of spacer molecules, and (v) a pulsed plasma polymerization of functional groups bearing monomers or (vi) their copolymerisation with other comonomers. The formation of hydroxyl (OH), primary amino (NH2), and carboxyl (COOH) groups was studied in detail. The oxygen plasma treatment (i) in a low-pressure non-isothermal glow discharge results in the formation of a wide variety of 0 functional groups, polymer degradation and crosslinking. Low power densities and short exposure times (0.1 to 2 s) are required to functionalize a surface while preserving the original polymer structure. Carbonate, ester, and aromatic groups are rapidly degraded by an oxygen plasma treatment leading to scissions of polymer backbones and loss in molecular weight. Also the formation of macrocycles and C=C bonds was observed in a region of around 4 nm in depth. The investigated polymers could be classified by their degradation behaviour on exposure to the oxygen plasma.In order to maximize the process selectivity for OH groups, the variety of oxygen functionalities formed by the oxygen plasma was wet-chemically reduced by diborane, vitride(TM) (Na. complex), and LiAlH4. Typical yields were 9 to 14 OH groups per 100 carbon atoms.Plasma bromination (iii) (40 Br per 100 C atoms) of polymers, followed by grafting of spacer molecules (iv), has been proved to be a highly selective reaction.Another way to produce high densities of monosort functionalities was the pulsed plasma polymerization of functional group bearing monomers such as allylamine, allylalcohol or acrylic acid (v). The retention of chemical structure and functional groups during plasma polymerization was achieved by using low power densities and the pulsed plasma technique. The maximum yields were 30 OH, 18 NH2, and 24 COOH groups per 100 C atoms. To vary the density of functional groups a chemical copolymerization with 'chain-extending' comonomers such as butadiene and ethylene was initiated in the pulsed plasma (vi). Additionally, the often-observed post-plasma oxidations of such layers initiated by reaction of trapped radicals with oxygen from the air were successfully suppressed by using NO gas as radical quencher.

Several possibilities exist to produce a modified polymer surface with a high density of only one sort of functional group such as: (i) the plasma grafting of unfragmented monomer molecules and their polymerization forms OH, NH2, COOH groups, etc. in concentrations of approximately 25 groups per 100 C atoms; (ii) selective plasma bromination provides 10–25 CBr groups; (iii) the plasma oxidation of polymer surfaces in an O2 plasma followed by the chemical reduction of all O-containing groups to OH groups by diborane, vitride™ (Na complex) or LiAlH4 yields 9–14 OH groups per 100 carbon atoms; and (iv) the grafting of spacers with different endgroups onto OH or CBr groups produces 7–10 spacer molecules/100 C. This work was focused on the formation of thin plasma deposited polymer layers with a maximum of (homo)functional groups and with a minimum of chemical irregularities using the pulsed plasma technique. The monomers were allylalcohol, allylamine, acrylonitrile and acrylic acid. The further intent was to study the interactions of functional groups (OH, COOH, NH2) and deposited metals (Cr, Al, Ti). It was expected that more basic (NH2), weakly basic or neutral (OH) or more acidic (COOH) groups would show different interactions and chemical reactions with metal atoms.