There are very few studies that have investigated directly the effect of an oxide film on tin whisker growth, since the 'cracked oxide theory' was proposed by Tu in 1994. The current study has investigated the effect of both a molybdate conversion coating and a tungstate conversion coating on tin whisker growth from Sn-Cu electrodeposits on Cu, and compared it with that from an electrochemically formed oxide produced from a potassium bicarbonate-potassium carbonate electrolyte. X-ray photoelectron spectroscopy (XPS) has been used to investigate the effect of both immersion time and applied potential on the thickness and composition of the oxide film. The XPS studies show that the oxide film formed using either of the conversion coating baths is significantly thicker than that produced from the potassium bicarbonate-potassium carbonate bath. Initial observations suggest that both the tungstate-based conversion coatings and the molybdate-based conversion coatings significantly reduce whisker growth by over 80% for all conversion coating systems compared with a native air-formed oxide and provide improved mitigation compared with the electrochemically formed oxides previously investigated.

An in situ colorimetric method, based on the CIE (Commission Internationale de l'Eclairage) system of colorimetry, has been applied to the study of the electrochromic N,N ́-bis(n-heptyl)-4,4 ́-bipyridylium (‘di-n-heptyl viologen’) system in aqueous solution on transmissive ITO/glass substrates. On electrochemical reduction of the di-n-heptyl viologen di-cation, the purple di-n-heptyl viologen radical cation salt deposits as a film and the changes in hue and saturation have been tracked using CIE 1931 xy chromaticity coordinates. The CIELAB 1976 colour space coordinates of the purple di-n-heptyl viologen radical cation salt were L* = 76, a* = 33 and b* = –20, with a complementary wavelength of 548 nm. A sharp decrease in luminance was found on formation of the di-n-heptyl viologen radical cation salt. Colour coordinates for the reverse (oxidation) direction plots show hysteresis, implying that specific choice of colour values depends on both the potential applied and from which direction the potential is changed.

The electrocatalysis of dopamine has been studied using a cobalt hexacyanoferrate film (CoHCFe)-modified glassy carbon electrode. Using a rotating disk CoHCFe-modified electrode, the reaction rate constant for dopamine was found to be 3.5 × 10 cm mol s at a concentration of 5.0 × 10 mol L. When a Nafion film is applied to the CoHCFe-modified electrode surface a high selectivity for the determination of dopamine over ascorbic acid was obtained. The analytical curve for dopamine presented linear dependence over the concentration range from 1.2 × 10 to 5.0 × 10 mol L with a slope of 23.5 mA mol L and a linear correlation coefficient of 0.999. The detection limit of this method was 8.9 × 10 mol L and the relative standard deviation for five measurements of 2.5 × 10 mol L dopamine was 0.58%.

Spectroelectrochemistry encompasses a group of techniques that allow simultaneous acquisition of electrochemical and spectroscopic information in situ in an electrochemical cell. A wide range of spectroscopic techniques may be combined with electrochemistry, including electronic (UV–visible) absorption and reflectance spectroscopy, luminescence spectroscopy, infrared and Raman spectroscopies, electron paramagnetic resonance spectroscopy and ellipsometry. In this article, the principles and practice of electronic spectroelectrochemistry are introduced.

Hybrid materials based on polyaniline (PAni) were obtained by in situ polymerization of aniline with chitosan and/or organically modified clay (nanomer I-24) in HCl.The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and direct current (DC) electrical conductivity.Thin films of PAni, PAni-clay, PAni-chitosan and PAni-chitosan-clay were prepared by casting a solution of each sample in N-methyl-2-pyrrolidone (NMP) onto indium tin oxide (ITO)/glass electrodes and their electrochromic properties were investigated.It was observed color variation from transparent yellow in the reduced state (E = -0.2V vs. Ag/AgCl), green in the intermediate state (E = 0.5 V) and dark blue in the oxidized state (E = 0.8 V) for all samples.The color changes of each material in function of the applied potential were tracked using the Commission Internationale de l'Eclairage (CIE) system of colorimetry, in which the color change was much more significant for PAni-clay film.

Second Edition of the Encyclopedia of Spectroscopy and Spectrometry pulls key information into a single source for quick access to answers and/or in-depth examination of topics. SPEC-2 covers theory, methods, and applications for researchers, students, and professionals - combining proven techniques and new insights for comprehensive coverage of the field. The content is available in print and online via ScienceDirect, the latter of which offers optimal flexibility, accessibility, and usability through anytime, anywhere access for multiple users and superior search functionality. No other work gives analytical and physical (bio)chemists such unprecedented access to the literature. With 30% new content, SPEC-2 maintains the 'authoritative, balanced coverage' of the original work while also breaking new ground in spectroscopic research. The key features of the book include: incorporates more than 150 color figures, 5,000 references, and 300 articles (30% of which are new), for a thorough examination of the field; highlights new research and promotes innovation in applied areas ranging from food science and forensics to biomedicine and health; and features a new co-editor: David Koppenaal of Pacific Northwest National Laboratory, Washington, USA, whose work in atomic mass spectrometry has been recognized internationally.

We here describe recent progress in conjugated polymers research for the design of materials that present both electrochromic and fluorescent properties. We focus on the importance of electrochemical techniques as important tools for the preparation of materials deposited onto electrode surfaces through electropolymerisation and the investigation of their properties according to the applied potential in order to apply them in optoelectronic devices. The first section is devoted to a brief overview concerning structure and properties of conjugated polymers. Next, we focus on recent advances concerning the synthesis, electrochemical and optical properties of the conjugated electrochromic and fluorescent polymers. Last, we underline the possibilities of application of such materials as active layers for electrochromic devices and organic light emitting diodes (OLEDs), and also as fluorescent electrochemical sensors.

Conjugated conducting polymers presenting both electrochromic and fluorescent properties have become one of the main research topics due to their notable advantages, such as low cost and simple production methods, processability, and the possibility of tuning the band gap (and the colour states) of the polymer by suitable choice of the monomer substituent [1] or by copolymerisation [2]. Oligothiophenes, such as terthiophene (TTh), constitute an interesting class of electroactive polymers with potential application in organic electronics that can be used as components of active layers for application in electronic devices such as Organic Light Emitting Diodes (OLEDs) and electrochromic devices. In order to modify the properties of TTh, this work has focused on the electrochemical copolymerisation of TTh with a pyrrole derivative, (R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5dinitrobenzoyl)-α-phenylglycinate, DNBP. The polymer PDNBP has already been investigated by our group and presents good results concerning its application as an electrochromic material [3].

The control of interfacial microstructural stability is of utmost importance to the reliability of liquid solder interconnects in high temperature electronic assemblies. This is primarily due to excessive intermetallic compounds (IMCs) that can form and continuously grow during high temperature operation, which renders conventional barrier metallizations inadequate. With the intention of reducing such excessive IMC growth, electrically conducting, NbOx containing Ni coatings were developed using electrodeposition and were assessed as solder diffusion barrier layers in terms of their electrical conductivity and barrier property. The present work adopts a novel electrochemical route to produce Ni-NbOx composite coatings of good uniformity, compactness and purity, from non-aqueous glycol-based electrolytes consisting of NiCl2 and NbCl5 as metal precursors. The effects of cathodic current density and NaBH4 concentrations on the surface morphology, composition and thickness of the coatings were examined. Increased NaBH4 concentrations were found to elevate the maximum deposit thickness (above 10 μm), although these led to a reduction in the co-deposited Nb content. The composite coatings generally exhibited good electrical conductivity. The reaction between a liquid 52In-48Sn solder and Ni-NbOx, with Nb contents up to 6 at.%, was studied at 200°C. The results indicate that, Ni-NbOx with sufficient layer thickness and higher Nb content, offered longer service lifetime. Nb enrichment was generally observed at or close to the reaction front after high temperature storage which suggests evident effectiveness of the enhanced diffusion barrier characteristics. A mechanism for the role of Nb as a barrier performance enhancer was postulated.

There are very few studies that have investigated directly the effect of an oxide film on tin whisker growth, since the 'cracked oxide theory' was proposed by Tu in 1994 [K.-N. Tu: Phys. Rev., 1994, 49, (3), 2030-2034]. The current study has investigated the effect of an electrochemically produced oxide on tin whisker growth, for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. X-ray photoelectron spectroscopy (XPS) has been used to investigate the effect of the applied electrochemical oxidation potential on the oxide film thickness. Focused ion beam has been used to prepare cross sections from electrodeposited samples to investigate the influence of the electrochemically formed oxide film on deposit microstructure during long-term room temperature storage. The XPS studies show that the thickness of electrochemically formed oxide film is directly influenced by the applied potential and the total charge passed. Whisker growth studies show that the electrochemical oxidation treatment mitigates whisker growth for both Sn-Cu electrodeposits on Cu and pure Sn electrodeposits on brass. For Sn electrodeposits on brass, the electrochemically formed oxide greatly reduces both the formation of zinc oxide at the surface and the formation of intermetallic compounds, which results in the mitigation of tin whisker growth. For Sn-Cu electrodeposits on Cu, the electrochemically formed oxide has no apparent effect on intermetallic compound formation and acts simply as a physical barrier to hinder tin whisker growth.

Stainless steels are used in an array of applications where their ability to take on colour is of aesthetic value. Although thermal colouring (heat tinting) is known, particularly in terms of its effect on welds, the surface development of thermally coloured stainless steel has not been considered in detail. This paper demonstrates the colour development of a bright annealed 304 stainless steel with time at temperature. The colour development has been quantified using colour spectrophotoscopy and the colour related to the growth of surface oxide features by scanning electron microscopy and the chemical profiles by X-ray photoelectron spectroscopy (XPS). There is a clear development of both the oxide thickness and chemistry, with increasing time with small nodules being the main features seen across the surface of the samples with time. The oxides have been shown to comprise of an outer iron rich oxide and an inner chromium/iron spinel layer.

The control of interfacial microstructural stability is of utmost importance to the reliability of liquid solder interconnects in high temperature electronic assemblies. This is primarily due to excessive intermetallic compounds (IMCs) that can form and continuously grow during high temperature operation, which renders conventional barrier metallisations inadequate. With the intention of reducing such excessive IMC growth, electrically conducting, NbOx containing Ni coatings were developed using electrodeposition and were assessed as solder diffusion barrier layers in terms of their electrical conductivity and barrier property. The present work adopts a novel electrochemical route to produce Ni-NbOx composite coatings of good uniformity, compactness and purity, from non-aqueous glycol-based electrolytes consisting of NiCl2 and NbCl5 as metal precursors. The effects of cathodic current density and NaBH4 concentrations on the surface morphology, composition and thickness of the coatings were examined. Increased NaBH4 concentrations were found to elevate the maximum deposit thickness (above 10 µm), although these led to a reduction in the co-deposited Nb content. The composite coatings generally exhibited good electrical conductivity. The reaction between a liquid 52In-48Sn solder and Ni-NbOx, with Nb contents up to 6 at.%, was studied at 200ºC. The results indicate that, Ni-NbOx with sufficient layer thickness and higher Nb content, offered longer service lifetime. Nb enrichment was generally observed at or close to the reaction front after high temperature storage which suggests evident effectiveness of the enhanced diffusion barrier characteristics. A mechanism for the role of Nb as a barrier performance enhancer was postulated.

The synthesis and fluorescence characterization of a new pyrrole derivative (PyPDG) containing the electron donor-acceptor dansyl substituent is reported. The effects of temperature and solvent polarity on the steady-state fluorescence of this compound are investigated. Our results show that PyPDG exhibits desirable fluorescent properties which makes it a promising candidate to be used as the photoactive material in optical thermometry and thermography applications. Further, the electrochemical and emission properties of polymeric films obtained from the oxidation polymerization of PyPDG are also analyzed. (C) 2014 Elsevier B.V. All rights reserved.

Ni-NbOx nano-composite coatings on Cu, from glycol-based electrolytes consisting of NbCl5, NiCl2 center dot 6H(2)O and propylene glycol. The effects of both cathodic current density and metal electrodeposition bath concentrations on the surface morphology and composition of the coating were examined. The highest relative metal percentage of co-deposited Nb was 14.3 at% obtained at a current density of 400 mA/cm(2). Scanning transmission electron microscopy (STEM) revealed a nanocrystalline FCC Ni structure without any significant lattice distortion, as well as an as-yet-unidentified compound. STEM X-ray mapping suggests Nb and O were uniformly distributed in the Ni matrix, without any significant phase segregation, which is consistent with XPS compositional depth profiling. Also, according to the XPS spectra, a 0.7 eV shift to lower binding energy for the Nb (V) species may suggest the partial chemical reduction of Nb2O5 due to possible Ni-Nb bonding. It is thus proposed that a Ni-NbOx deposit was formed by two parallel electrochemical reduction routes: 1) deposition of Ni metal; 2) deposition of a Ni-Nb-O compound as nano-clusters. (C) 2014 The Electrochemical Society. All rights reserved.

The copolymerisation of 3,3′″ Dihexyl-2,2′:5′,2″:5″,2′″-quaterthiophene (DHQT) and (R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate (DNBP) was successfully performed electrochemically in acetonitrile (CH3CN) containing tetrabutylammonium tetrafluoroborate ((C4H9)4NBF4) by direct oxidation of monomer mixtures in different feed ratios. Copolymerisation improved the properties of the films of both polymers PDHQT and PDNBP, in respect to the adhesion of PDHQT onto ITO/glass surface and the chromatic contrast of these electrochromic materials. PDHQT, PDNBP and P(DHQT-co-DNBP) films were characterised by FTIR spectroscopy, fluorescence spectroscopy, Scanning Electron Microscopy (SEM) and spectroelectrochemical techniques. Solutions of PDHQT and its copolymers with DNBP (independently of the feed ratio) in N-methylpyrrolidone are fluorescent with emission bands at 555 and 585nm when excited at 375nm. Reversible changes in the hue and saturation occur in all the copolymer films from yellow or orange in the reduced state to green or blue in the oxidised state, but were dependent on the proportion of the comonomers used to prepare the copolymers. These changes are more significant for P(DHQT-co-DNBP) films deposited onto ITO/glass with 1:5 feed ratio, as shown by the track of the CIE 1931 xy chromaticity coordinates and by the electrochromic parameters in which this film (thickness 0.8±0.2μm) presented chromatic contrast (Δ%T) at 660nm of 62%, coloration efficiency (η) of 266cm2C−1 and stability to redox cycling (Δ%T=17% at the 1000th cycle). Therefore, these copolymers are potentially applicable in displays and optoelectronic devices as electrochromic and fluorescent materials.

Electroplated tin finishes are widely used in the electronics industry due to their excellent solderability, electrical conductivity and corrosion resistance. However, the spontaneous growth of tin whiskers during service can result in localised electrical shorting or other harmful effects. Until recently, the growth of tin whiskers was successfully mitigated by alloying the tin with lead. However, restriction in the use of lead in electronics as a result of EU legislation (RoHS) has led to renewed interest in finding a successful alternative mitigation strategy.Whisker formation has been investigated for a bright tin electrodeposit to determine whether whisker growth can, at least partially, be mitigated by control of electroplating parameters such as deposition current density and deposit thickness. The influence of substrate material and storage at 55 degrees C/85% humidity on whisker growth have also been investigated.Whisker growth studies indicate that deposition parameters have a significant effect on both whisker density and whisker morphology. As deposition current density is increased there is a reduction in whisker density and a transition towards the formation of large eruptions rather than potentially more harmful filament whiskers. Increasing the tin coating thickness also results in a reduction in whisker density. Results demonstrate that whisker growth is most prolific from tin deposits on brass, whilst that from tin deposits on rolled silver is greater than that observed for tin deposits on copper. (C) 2014 The Authors. Published by Elsevier Ltd.