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Analytical and Bioanalytical Chemistry (v.375, #7)

Eloquence...speaking easily the first time. Is it possible? by John Fetzer (pp. 845-846).

12th Conference on Applied Surface Analysis—AOFA 12 by Hubert Gnaser (pp. 847-848).

Scanning-force techniques to monitor time-dependent changes in topography and adhesion force of proteins on surfaces by M. Mondon; S. Berger; C. Ziegler (pp. 849-855).

Scanning-force microscopy (SFM) investigations were conducted to probe the influences of the interactions of proteins with surfaces relevant in medicine. These interactions are an important feature in the area of biofilm formation. The adsorption of proteins leads to changes in topography, which was monitored for the build up of protein layers of hen egg-white lysozyme and bovine serum albumin (BSA) on mica in real time in phosphate-buffered aqueous solution over a time period of 10 min. Phase imaging was additionally applied to compare material contrasts and to evaluate this method for further application in this field. The adhesion forces that develop on a time scale below 20 s between a protein-modified SFM tip and titanium surfaces (TiO₂, TiAl6V4 and TiAl6Nb7) were investigated. The influences of the parameters loading force and interaction time between the protein and the surface were monitored as well as the influence of protein structure. The interaction time dependency of the adhesion force could be described with a kinetic model of two consecutive first-order reactions. For the maximal adhesion force a correlation to the ratio of the amino acids cysteine, proline and glycine has been proposed.

Keywords: Scanning-force microscopy Protein adsorption Adhesion force TiO2 TiAl6V4 TiAl6Nb7 Kinetics

Unifit 2002—universal analysis software for photoelectron spectra by R. Hesse; T. Chassé; R. Szargan (pp. 856-863).

The current level of development of the spectra analysis software Unifit for Windows is presented and evaluated by checking with test spectra. The program is characterized and the correctness of the numerical routines is demonstrated for the particular cases of the Shirley type background model and the Gaussian–Lorentzian product model functions. Different approaches to an optimum fit result are suggested. A convenient analysis of the assessment of the peak fit procedure is proposed. All results are presented in tabular form too, to make the data more comprehensible.

Keywords: Unifit for Windows Spectrum analysis software Photoelectron spectroscopy Shirley type background model Gaussian–Lorentzian product model

STS investigations to describe corrosion procedures on thin CrN layers by Wieland Zahn; Antje Zösch; Hans-Dieter Schnabel (pp. 864-870).

To represent the corrosion characteristics of thin hard material layers, CrN layers, which were magnetron sputtered, have been exposed to solutions with chloride or sulfate ions. The alterations of the layer surfaces were examined. Static immersion tests were carried out ex-situ in 1 mol L⁻¹ NaCl or 1 mol L⁻¹ Na₂SO₄ solution over a period of 14 months. For in-situ measurements, the layers were inserted into the electrochemical cell of an EC STM as the working electrode. The sample potential was altered cyclically. At the same time, voltammograms were taken and the topography alteration was observed.Alterations in the surface structure were documented as hybrid information resulting from changes in topography and the chemical consistency or the thickness of the oxide layers. These modifications were demonstrated with scanning tunnelling spectroscopy before and after the treatment with solutions. Several chemical phases (initial state and oxide layers) were distinguished with raster tunnelling spectroscopy (measurements I(V) and I(z)). The evaluation of the I(z) spectroscopy showed that the tip was in mechanical contact with the sample if an oxide layer of greater thickness has existed.Exemplary XPS investigations demonstrated corrosive alterations of the CrN layers due to oxidation. Asymmetry and peak locations suggest that in addition to Cr₂O₃ and CrN a complex mixture of different chromium oxides such as Cr₂O₃ and Cr(OH)_x exists.

Keywords: Coating Chromium nitride STS EC STM XPS Corrosion Surface structure

EC STM investigations of corrosion due to chloride solutions on thin CrN coatings by Wieland Zahn; Antje Zösch; Hans Dieter Schnabel (pp. 871-874).

The focus of the investigations presented is to evaluate local alterations caused by chloride ions affecting thin, magnetron-sputtered CrN layers. Scanning-probe microscopy and analysis techniques are used for this estimation. Thin CrN layers were deposited by reactive magnetron sputtering. They were investigated in electrochemical scanning tunnelling microscopy (EC STM) by cyclic voltammetry in 1 mol L^–1 NaCl. Simultaneously, the surface topography changes were recorded with STM.Above 100 mV the anodic oxidation leads to formation of chromium(III) hydroxide and at sample potentials above 350 mV oxidation of Cr(OH)₂ and Cr(OH)₃ towards chromium(VI) as a soluble chromate starts. Transpassive dissolution of the coating takes place above 900 mV. Yellow colour of the electrolyte is a visible sign for the formation of chromium(VI). Changes of the surface topography indicate the formation of surface layers at anodic potentials. At cathodic potentials increase in current is measured due to the reduction of chromium(III) hydroxide to divalent chromium and metallic chromium. Roughness of surface topography increases.Follow-up explorations with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic-force microscopy (AFM), scanning tunnelling microscopy/scanning tunnelling spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS) not only evidence the formation of various chromium oxides, but also indicate the existence of chromium hydroxide.

Keywords: Coating Chromium nitride EC STM Voltammetry Corrosion Surface structure

Analysis of functional groups on the surface of plasma-treated carbon nanofibers by Stephan Haiber; Xingtao Ai; Henning Bubert; Moritz Heintze; Volker Brüser; Waltraut Brandl; Gabriela Marginean (pp. 875-883).

Plasma chemically modified carbon nanofibers were characterized by X-ray photoelectron spectroscopy with regard to the content of carbon, oxygen, and nitrogen and the contribution of carboxylic groups or ester, carbonyl and hydroxylic groups or ether on the surface. Unfortunately, X-ray photoelectron spectroscopy only provides an average value of the first 10 to 15 molecular layers. For comparison, depth profiles were measured and wet chemical methods were applied to estimate the thickness of the functionalized layer and the distribution of oxygen-containing functional groups within the near-surface layers. The results indicate that the fiber surface is covered by a monomolecular oxygen-containing layer and that plasma treatment allows a complete oxygen functionalization of the uppermost surface layer. The best conditions for plasma treatment found within the set of parameters applied to generate complete functionalization are: plasma gas O₂/Ar ratio 1:1, gas pressure 1–1.5 hPa, plasma power 80 W, treatment time ≥ 5 min. Additionally, three quick and easy methods are presented to estimate the efficiency of plasma treatment with regard to surface functionalization: pyrolysis, contact angle measurements, and light permeability measurements of aqueous carbon nanofiber suspensions.

Keywords: Nanofibers Plasma treatment Surface characterization Functional groups X-ray photoelectron spectroscopy

Comparative investigations of structure and properties of BCN coatings deposited by thermal and plasma-enhanced CVD by S. Stöckel; K. Weise; T. Thamm; K.-U. Körner; D. Dietrich; G. Marx (pp. 884-890).

Hard BCN films were deposited by chemical vapour deposition (CVD) on Si(100) substrates. TCVD (thermal activated) and PECVD (GD or RF microwave plasma-activated, respectively) were used. The films were analysed with respect to chemical state, composition, morphology and microstructure, oxidation behaviour and hardness. Wavelength dispersive X-ray spectroscopy (EPMA), infrared spectroscopy (IR), transmission electron microscopy (TEM), differential thermal analysis (DTA) and hardness evaluation were employed for film characterization. A correlation between deposition parameters and film composition, structure and hardness could be proved in every CVD process. Parallels between TCVD and PECVD films emerged in the case of chemical composition and the correlation between carbon content and hardness values. Considerable differences exist with regard to the microstructure, especially the texture of the films. Moreover in TCVD films the carbon is preferentially incorporated between the BN basal planes, whereas in PECVD films it is incorporated preferentially in as well as between the BN basal planes.

Keywords: Chemical vapour deposition (CVD) Coatings BCN Hardness Structural properties

AES and SIMS investigation of diffusion barriers for copper metallization in power-SAW devices by S. Baunack; S. Menzel; M. Pekarčíková; H. Schmidt; M. Albert; K. Wetzig (pp. 891-895).

Barrier layers for Cu-metallization in surface acoustic wave (SAW) devices were investigated by AES and SIMS depth profiles. Two layered systems on LiNbO₃ substrate have been analyzed after annealing in air up to 400 °C. The investigated systems were (A) Ta(20 nm)/Cu(150 nm)/Ti(30 nm), deposited by electron beam evaporation, and (B) Ta₃₀Si₁₈N₅₂(50 nm)/Cu(150 nm)/Ta₃₀Si₁₈N₅₂(50 nm) deposited by magnetron sputtering. In system A the Ta layer shows oxidation in air for T≥300 °C. Ti from the buffer layer diffuses into the Cu at about 100 °C, and segregates at the Ta/Cu interface for T≥200 °C. Oxidation of the Ti layer starts at 300 °C. But no remarkable amounts of oxygen could be found in the Cu film. The depth profiles show that the TaSiN layer in system B operates as a more effective barrier for the Cu-SAW technology up to more than 300 °C.

Keywords: Cu metallization Diffusion barrier Depth profiling AES SIMS

Characterization of oxide layers on amorphous Mg-based alloys by Auger electron spectroscopy with sputter depth profiling by S. Baunack; R. V. Subba Rao; U. Wolff (pp. 896-901).

Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL₂₃L₂₃) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL₂₃L₂₃) and Cu(L₂₃VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.

Keywords: Amorphous metal Auger electron spectroscopy Depth profiling Preferential sputtering

XPS investigations of thin tantalum films on a silicon surface by M. Zier; S. Oswald; R. Reiche; K. Wetzig (pp. 902-905).

Ultra thin tantalum-based diffusion barriers are of great interest in copper metallisation technology. Even the smallest amounts of copper that diffuse into the active silicon regions on a microprocessor will alter their semiconducting properties thus leading to failure of the device. In the present work Ta films were deposited on silicon by electron beam evaporation and magnetron sputtering. The background of this study is investigation of interface formation, which is expected to have substantial influence on the properties of thin Ta films. All experiments were carried out under UHV conditions. This was necessary because Ta is a very reactive metal and is readily oxidized even at low oxygen partial pressure. The Ta4f peak, as a sensitive indicator of the chemical state, was analysed and compared to that for standard samples. Silicide formation is assumed to occur at the Ta/Si interface.

Keywords: Tantalum Silicon Diffusion barrier XPS Interface

XRF and SIMS/SNMS analyses of Ba_xSr_1−xTiO₃ dielectrics by U. Breuer; W. Krumpen; F. Fitsilis (pp. 906-911).

The development of analytical tools and procedures for process control is a prerequisite for the integration of high permittivity and/or ferroelectric materials in CMOS devices. The thickness and composition of perovskite oxide films were determined by wavelength dispersive X-ray fluorescence analysis (XRF) with special emphasis on the ratio of the group-II elements to the Ti content, and a precision of 0.5% was achieved for a typical film thickness of 20–30 nm. Secondary ion mass spectrometry (SIMS) and sputtered neutrals mass spectrometry (SNMS) was used for depth profiling to determine film homogeneity and elemental interdiffusion at hetero-interfaces. Examples are given for Ba_xSr_1−xTiO₃ and SrTiO_x thin films which were grown in a prototype MOCVD production tool. No interdiffusion was observed for films grown at 600 °C on Pt electrodes in contrast to films grown directly on Si.

Keywords: XRF SIMS SNMS MOCVD BST DRAM

Adsorption/desorption studies on nanocrystalline alumina surfaces by Yong Men; Hubert Gnaser; Christiane Ziegler (pp. 912-916).

Two kinds of nanocrystalline alumina powders, boehmite (γ-AlOOH, particle size d ≈ 10 nm, BET surface area A _BET = 180–200 m² g⁻¹) and corundum (α-Al₂O₃, d ≈ 400 nm, A _BET = 7 m² g⁻¹) were used for comparative investigation by thermogravimetry (TG). The remarkable difference in the dehydration profiles between the two samples gives evidence for a distinct difference in their structures. In the following pyridine adsorption/desorption experiment, γ-alumina was found to possess much more (20 times) and much stronger acidic sites than corundum. The activation energy of pyridine desorption was obtained from the respective minima in the first derivative of the TG-curves (DTG) at various heating rates (1–20 K min⁻¹); the activation energy for pyridine desorption is smaller for γ-alumina (61.5 kJ mol⁻¹) than for corundum (78.8 kJ mol⁻¹). Furthermore, the adsorption of water, carbon tetrachloride, and hexane on those alumina specimens provides evidence for the highly hydrophilic nature of their surfaces. The shift of T _max to higher temperatures upon desorption of water was ascribed to the different adsorption coverage and the different energy required for removal of adsorbed water molecules.

Keywords: Thermal analysis Alumina Pyridine Adsorption Desorption Activation energy

Characterization of nanocrystalline anatase TiO₂ thin films by Bernd Huber; Hubert Gnaser; Christiane Ziegler (pp. 917-923).

Nanoporous thin films were deposited onto glass substrates by painting with a solution of nanocrystalline anatase TiO₂ particles (with a size of either 6 nm or 16 nm) suspended in an organic solvent. Upon drying in air for about 1 day, the films were tempered at 450 °C in air for 1 h. This procedure results in stoichiometric TiO₂ films with a thickness of several µm and a milky whitish appearance. Scanning force microscopy of the surface revealed that the nanoparticles of the films agglomerated into structures with lateral dimensions of some 100 nm. Transmission electron microscopy was utilized to investigate the structural arrangement of the crystallites in the films. High-resolution electron diffraction and X-ray diffraction analyses demonstrated, furthermore, that the material consists exclusively of a single TiO₂ phase, namely anatase, and that the films do not exhibit any preferential texture. The elemental stoichiometry and the possible presence of impurities were monitored throughout the films by means of secondary-ion mass spectrometry depth profiling. Electrical measurements have been carried out as a function of both the sample temperature T and the ambient oxygen partial pressure p(O₂). From these data the electrical conductivity σ of the porous films was determined in dependence of those parameters.

Keywords: Nanocrystalline titanium dioxide Anatase Oxygen sensing

Nanostructures on La-doped SrTiO₃ surfaces by A. Gunhold; K. Gömann; L. Beuermann; V. Kempter; G. Borchardt; W. Maus-Friedrichs (pp. 924-928).

SrTiO₃(100) single crystals with high donor dopant concentrations (5 at% La) were annealed at 1000 °C for up to 150 h in ultrahigh vacuum (UHV). By applying scanning tunneling microscopy (STM) nanostructures are observed on top of the surface with typical diameters of 20 nm and typical heights of 8 nm. To characterize their electronic structure and chemical composition, the surface was analyzed by metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling spectroscopy (STS), and depth profiling Auger electron spectroscopy (AES). Investigations of the stoichiometry suggest that the secondary phases consist of LaTiO₃. We present a defect chemistry model which attempts to explain the observed effects.

Keywords: SrTiO3 LaTiO3 MIES UPS AES STM STS

XPS, AES, and AFM as tools for study of optimized plasma functionalization by U. Vohrer; D. Hegemann; C. Oehr (pp. 929-934).

The plasma-based surface modification of polymer materials with desirable bulk properties is a useful way to obtain polymers with tailor-made surface properties. This is necessary because the surface properties of most engineering polymers in use today are less then optimum for many applications. New functionalities such as biocompatibility, adhesion, special functional groups as well as lubricative, friction and wear-and-tear properties are demanded. By optimization of the process parameters during a low pressure plasma treatment, most of these requirements can be fulfilled. A specific functionalization with, e.g., carboxyl, amino, epoxy or hydroxyl groups as well as the generation of ultra thin layers with those functionalities is possible. The most challenging problem is not only to find parameters which do not lead to a fragmentation of the monomeric structure, but moreover the adhesion of the thin films to the substrates must overcome a stability test without delamination. To optimize plasma processes, with their great variety of parameters influencing the obtained surface properties, several surface analytical techniques are indispensable. XPS, AES as well as AFM are helpful tools to characterize the modified sample surfaces and consequently optimize the set of parameters for the glow discharge treatment. With XPS the retention of the monomer structure can be controlled. AES depth profiling clarifies the elemental composition of gradient layers, necessary for a good adhesion of scratch-resistant coatings. AFM visualizes the surface morphology which is important for, e.g., the friction properties of plasma-coated substrates.

Keywords: Plasma treatment Polymer Functionalization Scratch resistance XPS AES AFM

Modeling the chemistry of plasma polymerization using mass spectrometry by D. F. Ihrig; J. Stockhaus; F. Scheide; Oliver Winkelhake; Oliver Streuber (pp. 935-941).

The goal of the project is a solvent free painting shop. The environmental technologies laboratory is developing processes of plasma etching and polymerization. Polymerized thin films are first-order corrosion protection and primer for painting. Using pure acetylene we get very nice thin films which were not bonded very well. By using air as bulk gas it is possible to polymerize, in an acetylene plasma, well bonded thin films which are stable first-order corrosion protections and good primers. UV/Vis spectroscopy shows nitrogen oxide radicals in the emission spectra of pure nitrogen and air. But nitrogen oxide is fully suppressed in the presence of acetylene. IR spectroscopy shows only C=O, CH₂ and CH₃ groups but no nitrogen species. With the aid of UV/Vis spectra and the chemistry of ozone formation it is possible to define reactive traps and steps, molecule depletion and processes of proton scavenging and proton loss. Using a numerical model it is possible to evaluate these processes and to calculate theoretical mass spectra. Adjustment of theoretical mass spectra to real measurements leads to specific channels of polymerization which are driven by radicals especially the acetyl radical. The estimated theoretical mass spectra show the specific channels of these chemical processes. It is possible to quantify these channels. This quantification represents the mass flow through this chemical system. With respect to these chemical processes it is possible to have an idea of pollutant production processes.

Keywords: Corrosion protection Acetylene plasma Acetyl radical Nitrogen oxide radical Mass spectrometry Theoretical mass spectra Plasma polymerization

Determination of antibiotics such as macrolides, ionophores and tiamulin in liquid manure by HPLC–MS/MS by Michael P. Schlüsener; Kai Bester; Michael Spiteller (pp. 942-947).

A method for the analysis of several macrolide and ionophore antibiotics as well as tiamulin in liquid manure was developed. Reversed-phase liquid chromatography and atmospheric pressure chemical ionisation (APCI) tandem mass spectrometry was used for detection.High-performance liquid chromatographic (HPLC) separation of the antibiotics was achieved in 35 min. The analytes were extracted with ethyl acetate and the extracts were cleaned up by solid-phase extraction on a diol SPE cartridge. Recovery experiments with spiked liquid manure concentrations varying from 6 to 2,000 µg kg⁻¹ gave constant recovery rates. The recovery rates for the macrolides erythromycin, roxithromycin and oleandomycin were 75–94%, that for the ionophore salinomycin was 119%, while that for the pleuromutilin tiamulin was 123%, when using a macrolide internal standard. The relative standard deviation was found to be 15–36% and the limits of detection were 0.4–11.0 µg kg⁻¹.The maximum concentrations found in manure samples were 43 µg kg⁻¹ for tiamulin and 11 µg kg⁻¹ for salinomycin.

Keywords: Agriculture Antibiotics APCI HPLC–MS/MS Liquid manure

Application of stir bar sorptive extraction for wine analysis by Yoji Hayasaka; Kevin MacNamara; Gayle A. Baldock; Randell L. Taylor; Alan P. Pollnitz (pp. 948-955).

Stir bar sorptive extraction (SBSE) coupled with gas chromatography/mass spectrometry (GC/MS) was used to analyse wine samples for three applications: flavour and compositional analysis; 2,4,6-trichloroanisole (TCA), a common off-aroma in wine; and agrochemicals. SBSE was found to be orders of magnitude more sensitive than modern conventional methodology, allowing for lower detection and quantitation levels, and improved confirmation of identity; SBSE often gave better signal to noise in scan mode than other methods in selective ion monitoring (SIM) mode. With the help of their characteristic mass spectra all agrochemicals could be identified unambiguously at concentrations of 10 μg L⁻¹ in wine and a further 100 constituents were detected in a Cabernet Sauvignon sample. Thus it is now possible to analyse complex samples such as wine by scan mode, with better confirmation of identity, and without sacrificing sensitivity, where previously SIM methodology had to be used.

Keywords: GC/MS SBSE Wine TCA Agrochemical Flavour

Interactions of diethylenetriaminepentaacetic acid (dtpa) and triethylenetetraaminehexaacetic acid (ttha) with major components of natural waters by Concetta De Stefano; Antonio Gianguzza; Daniela Piazzese; Silvio Sammartano (pp. 956-967).

The binding ability of diethylene triamine pentaacetate (dtpa⁵⁻) and triethylene tetraamine hexaacetate (ttha⁶⁻) ligands towards major components, H⁺, Na⁺, Mg²⁺ and Ca²⁺, of natural waters was studied in both single and mixed ionic media at different ionic strengths and at T=25 °C. Some measurements, performed in Mg²⁺–Ca²⁺ mixtures, allowed us to find the formation of new mixed species MgCa(dtpa), MgCa(ttha) and MgCaH(ttha), here reported for the first time. All the complexes formed in the various systems were characterized in terms of both stoichiometry and stability, and an attempt was made to find general rules for the stability of mixed metal complexes in comparison with that of simple species. To obtain quantitative information on the complexing ability of dtpa and ttha in seawater, measurements have been carried out in artificial seawater ionic medium (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻ and SO₄ ²⁻). Calculations, performed by considering the salt mixture as single salt BA, allowed us to find some quite stable B_iH_jL species. Under the natural seawater conditions [S(salinity)=35], we found for the most important species logβ_B(dtpa)=9.64 and % MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfKttLearuavP1wzZbqeduuDJXwAKbYu51 % MyVXgatCvAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDha % rqqr1ngBPrgifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8 % qqaqFr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9 % q8qqQ8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaake % aacyGGSbaBcqGGVbWBcqGGNbWzcqaHYoGydaWgaaWcbaGaeeOqai0a % aSbaaWqaaiabbkdaYaqabaWccqqGOaakcqqGKbazcqqG0baDcqqGWb % aCcqqGHbqycqqGPaqkaeqaaOGaeeypa0JaeeymaeJaeeimaaJaeeOl % a4IaeeOmaidaaa!4CFC! $$ log eta _{{ m{B}}_{ m{2}} { m{(dtpa)}}} { m{ = 10}}{ m{.2}} $$ . Literature data comparison is also reported.

Keywords: Polyaminocarboxylic ligands Interactions with inorganic components of natural water Single salt approximation for seawater Speciation Environmental coordination chemistry

Investigation of mechanical properties of anodized aluminum using dilatometric measurements by V. Sokol; I. Vrublevsky; V. Parkun; K. Moskvichev (pp. 968-973).

Mechanical properties of anodized aluminum were studied using the results of dilatometric measurements of thermal expansion of anodized Al (the symmetric structure Al₂O₃–Al–Al₂O₃). The 100-μm-thick Al₂O₃oxide layer was formed in 4% aqueous solution of oxalic acid in the galvanostatic regime at a current density of 20 mA cm⁻². Measurements of thermal expansion of anodized Al (Al and Mg alloy of 2.7–3.2%, and 0.3–0.6% Mn, and 0.5–0.8% Si) with the thickness of initial Al from 0.6 to 3.7 mm and ceramic from Al₂O₃ in the temperature range of 20–500 °C were conducted using an automatic quartz dilatometer. Intrinsic stress in the Al layer, the values of the modulus of elasticity, and the porosity of Al oxide formed on Al of different thickness are calculated.

Keywords: Anodized aluminum Stress Thermal expansion Yield strength of aluminum Modulus of elasticity Dilatometric measurements

Application of GRAM and TLD to the resolution and quantitation of real complex multicomponent mixtures by fluorescence spectroscopy by A. Garrido Frenich; D. Picón Zamora; M. Martínez Galera; J. L. Martínez Vidal (pp. 974-980).

The application of the generalised rank annihilation method (GRAM) and the trilinear decomposition (TLD) method to the resolution and quantitation of fluorescence excitation–emission matrices of a ternary mixture of pesticides, carbendazim, fuberidazole, and thiabendazole, with overlapped spectra is described. The results obtained with both methods are compared and evaluated using measures of similarity (correlation coefficients) between the real and estimated spectra. Both approaches have been tested using augmented data matrices containing only two samples, but none of these methods succeeded completely in resolution of the system. When TLD was applied to augmented data matrices containing more than two samples better performance was achieved. To illustrate the application of both algorithms to real samples, they were used in the analysis of water samples containing the target pesticides. Again, TLD had an advantage over GRAM because the ability to analyse data from multiple (more than two) samples simultaneously allowed the resolution of the mixtures.

Keywords: Three-way analysis GRAM TLD Fluorescence excitation emission matrix Pesticides

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Analytical and Bioanalytical Chemistry (v.375, #7)