Selzer Y, Mandler D. Comprehensive treatment of sphere-cap microelectrodes (SCMs) using digital simulations. Electrochem. Commun.Electrochemistry Communications. 1999;1 (12) :569 - 575.Abstract
The alternating direction implicit finite difference method (ADIFDM) was used to simulate the steady-state as well as the transient (chronoamperometric) behavior of sphere-cap microelectrodes (SCMs). The necessary steps to implement the ADIFDM for solving the rather complex geometry involved are described. The results for the steady-state behavior are in excellent agreement with a previously suggested anal. soln. making the ADIFDM an excellent tool to develop a comprehensive theory for SCMs. [on SciFinder(R)]
Borgwarth K, Rohde N, Ricken C, Hallensleben ML, Mandler D, Heinze J. Electroless deposition of conducting polymers using the scanning electrochemical microscope. Adv. Mater. (Weinheim, Ger.)Advanced Materials (Weinheim, Germany). 1999;11 (14) :1221 - 1226.Abstract
Electrochem. polymn. of 2',5'-bis(1-methylpyrrol-2-yl)thiophene (NSN) was carried out by scanning electrochem. microscopy, using Ru(bpy)33+ as oxidant for the polymn. process and for the ultramicroelectrode surface-distance probe. While this led to deposition of flat layers of polymer on a PMMA substrate, use of the weak oxidant IrCl62- gave sets of thin needles. Micrographs of the various patterns are shown (with resolns. of ≈ 15 μm) and the mechanism of polymn. is discussed. [on SciFinder(R)]
Muskal N, Mandler D. Thiol self-assembled monolayers on mercury surfaces: the adsorption and electrochemistry of ω-mercaptoalkanoic acids. Electrochim. ActaElectrochimica Acta. 1999;45 (4-5) :537 - 548.Abstract
The formation of self-assembled monolayers (SAMs) of ω-mercaptoalkanoic acids on a mercury surface under potential control was studied. Cyclic voltammetry and a.c. voltammetry were used for studying the different phases and transitions that the homologous series of these thiols form and undergo. The thiols are either physisorbed or chemisorbed depending on the applied potential and the transition between these two states occurs through a faradaic process. Also, the chemisorption of the thiols results in multilayer deposition when the thiol monolayer does not block electron transfer. Finally, the implications of this study to the formation and manipulation of SAMs of ω-functionalized alkanethiols on Hg are discussed. [on SciFinder(R)]
Migron Y, Hocherman G, Springer E, Almog J, Mandler D. Visualization of sebaceous fingerprints on fired cartridge cases: a laboratory study. J Forensic SciJournal of forensic sciences. 1998;43 (3) :543 - 8.Abstract
The visualization and endurance of fingerprints on cartridge cases after the firing process have been examined. Cartridges of M16, AK-47 (Kalashnikov) and Parabellum have been tested. Despite difficulties in visualizing these fingerprints, it was found that in some cartridge cases under laboratory conditions--for instance, on M16 brass cartridges--substantial parts of the fingerprints remain intact after shooting. The careful use of illumination after metal vapor deposition enabled visualization. Different possible mechanisms responsible for the partial destruction of the fingerprints are discussed.[on SciFinder (R)]
Sivan O, Erel Y, Mandler D, Nishri A. The dynamic redox chemistry of iron in the epilimnion of Lake Kinneret (Sea of Galilee). Geochim. Cosmochim. ActaGeochimica et Cosmochimica Acta. 1998;62 (4) :565 - 576.Abstract
Fe redox chem. was studied in Lake Kinneret (Sea of Galilee), a mesotrophic, monomictic lake in the central part of the Jordan Rift Valley, Israel. Fe2+ and total Fe concns. in the epilimnion and hypolimnion were measured; relationships between Fe2+ and other parameters (e.g., light, pH) were examd. In addn., lab. expts. were conducted where filtered (biota-free) Lake Kinneret water, sterile unfiltered Lake Kinneret water, and distd. water were spiked with various Fe3+ and Fe2+ concns. Fe3+ and Fe2+ concns. were measured as a function of time in water samples under a variety of pH, O2, and radiation conditions. Fe2+ concns. in the epilimnion were below detection limits (0.04 μM) during nighttime, whereas in daytime, Fe2+ concns. were always above detection limits and changed significantly throughout the year (0.05-0.15 μM). Fe2+:Fe(tot) ratios measured in the lake (3-99%) were higher than expected values for a high pH (pH ∼8), low ionic strength (∼10 mM) aquatic system. In addn. to photo-induced redn. of Fe3+, there was strong evidence that Fe2+ is stabilized in O2-satd. lake water, since Fe2+ concns. were detected at a depth of 10 m, where <10% of light penetrates. Results of oxidn. and photoredn. expts. suggested obsd. rates of Fe redox reactions in sterile lake water were consistent with known chem. (abiotic) rates, but that these rates cannot account for obsd. Fe2+ concns. in epilimnetic water. Therefore, it was proposed that the photo-induced Fe redox cycle in the epilimnion of Lake Kinneret is largely controlled by biol. activity and that abiotic photoredn. of Fe accounts for only a small fraction of Fe2+ in the epilimnion. [on SciFinder(R)]
Turyan I, Mandler D. Two-Dimensional Polyaniline Thin Film Electrodeposited on a Self-Assembled Monolayer. J. Am. Chem. Soc.Journal of the American Chemical Society. 1998;120 (41) :10733 - 10742.Abstract
A two-dimensional conducting polyaniline (PAN) monolayer has been formed on an elec. insulating monolayer. The approach is based on the electrochem. polymn. of surface-confined anilinium ions that were electrostatically attached to a neg. charged self-assembled monolayer of ω-mercaptodecanesulfonate (MDS), HS(CH2)10SO3-, on a gold surface. The formation and characterization of the two-dimensional film and the MDS monolayer have been examd. by cyclic voltammetry, Fourier transform IR spectroscopy, XPS, wettability, and scanning electrochem. microscope. The formation of a capacitor-like assembly, in which electron transfer was blocked between PAN and the gold surface, was accomplished by electrochem. incorporating hexadecanethiol (C16) into the MDS monolayer. The PAN monolayer exhibits properties similar to those of a thin polymer film. [on SciFinder(R)]
Turyan I, Mandler D. Selective Determination of Cr(VI) by a Self-Assembled Monolayer-Based Electrode. Anal ChemAnalytical chemistry. 1997;69 (5) :894 - 7.Abstract
We have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels as low as 1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the analytical performance of these electrodes have been studied in detail and optimized. In addition, the organization of the monolayers has been examined by a variety of surface techniques such as XPS, FT-IR, and electrochemistry. Our results show that structuring and understanding the solid-liquid interface at the molecular level are essential for designing probes with superior analytical characteristics.[on SciFinder (R)]
Mandler D, Turyan I.; 1997. Determination of chromium by cyclic voltammetry.Abstract
A highly sensitive assay for the detn. of Cr(VI), in the presence of Cr(III) and in the presence of other cations by cyclic voltammetry. The detn. is carried out with a gold or gold-plated electrode with a self-assembled monolayer of a pyridine deriv. of the kind of 4-(2-ethanethiol) pyridine. Detns. can be effected at extremely low levels of the order of 1 ppt (part per trillion, 1012). [on SciFinder(R)]
Turyan I, Mandler D. Selective Determination of Cr(VI) by a Self-Assembled Monolayer-Based Electrode. Anal. Chem.Analytical Chemistry. 1997;69 (5) :894 - 897.Abstract
The authors have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels ≥1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the anal. performance of these electrodes were studied in detail and optimized. The organization of the monolayers was examd. by a variety of surface techniques such as XPS, FTIR, and electrochem. Structuring and understanding the solid-liq. interface at the mol. level are essential for designing probes with superior anal. characteristics. [on SciFinder(R)]
Turyan I, Mandler D. Self-assembled monolayers in electroanalytical chemistry: a molecular sieve based on ω-mercaptoalkanesulfonic acid monolayers. Proc. - Electrochem. Soc.Proceedings - Electrochemical Society. 1997;97-19 (Chemical and Biological Sensors and Analytical Electrochemical Methods) :271 - 277.Abstract
A disorganized monolayer of ω-mercaptoalkanesulfonic acid, HS(CH2)nSO3H, serves as selective mol. sieve, which is selectively permeable to electroactive species. Due to the strong acidity of the sulfonic acid moiety the monolayers are highly charged in aq. soln. throughout most of the pH range. Cyclic voltammetry of neg. charged inorg. species, such as hexacyanoferrate, clearly shows the repulsion of these species from the solid-liq. interface. Cyclic voltammetry of pos. charged ions, e.g., hexaammineruthenium(III), is not influenced at all by the presence of a mercaptodecanesulfonic acid monolayer, suggesting a partial coverage of the gold substrate by the monolayer. Fe(III) ions were detd. by Osteryoung square wave voltammetry in the presence of both inorg. anions and sol. org. species. [on SciFinder(R)]
Schneeweiss MA, Kolb DM, Liu DZ, Mandler D. Anodic oxidation of Au(111). Can. J. Chem.Canadian Journal of Chemistry. 1997;75 (11) :1703 - 1709.Abstract
The initial stages of the anodic oxidn. of Au(111) were studied by cyclic voltammetry as well as in situ scanning tunneling microscopy (STM). Probably the place exchange process, which initiates the oxide formation, starts at step edges. The oxide phase was imaged in situ by scanning tunneling and at. force microscopy (AFM). The topog. information acquired by the two techniques is compared. [on SciFinder(R)]
Turyan I, Mandler D. Characterization and electroanalytical application of ω-mercaptoalkanesulfonic acid monolayers on gold. Isr. J. Chem.Israel Journal of Chemistry. 1997;37 (2-3) :225 - 233.Abstract
Self-assembled monolayers (SAMs) of ω-mercaptoalkanesulfonic acid on Au surfaces were studied by electrochem. and other surface techniques. In spite of the fact that these monolayers are disorganized, i.e., of brush type, they are impermeable to inorg. anions due to their high neg. charge. Also, an ω-mercaptodecanesulfonic acid (MDS) monolayer is also impermeable to org. species, regardless of their charge, because of its high hydrophilicity. The combination of these properties made it possible to apply Au electrodes modified with MDS for the detn. of Fe(III) ions in the presence of org. species that are either electroactive throughout the same potential window or form strong complexes with Fe(III). [on SciFinder(R)]
Migron Y, Mandler D. Development of latent fingerprints on unfired cartridges by palladium deposition: a surface study. J. Forensic Sci.Journal of Forensic Sciences. 1997;42 (6) :986 - 992.Abstract
Visualized fingerprints on unfired brass cartridge cases developed by a novel method of palladium deposition were examd. by Auger electron spectroscopy (AES), SEM, and electron probe microscopy (EPMA). In spite of the strong contrast of colors between the ridges and the valleys of the developed images, which suggests a selective coating of palladium on the valleys, palladium was found to deposit onto both valleys and ridges. Lumps of org. material were scattered mostly along the ridges. The study suggests a model for the deposition of metals on brass cartridges on which sebaceous fingerprints were impressed. [on SciFinder(R)]
Mandler D, Rubinstein I, Editors. Electrochemistry of Organized Systems. [In: Isr. J. Chem., 1997; 37(2-3)]. Laser Pages Publ; 1997 pp. 160 pp.
Mandler D, Rubinstein I. Foreword by the Guest Editors. Isr. J. Chem.Israel Journal of Chemistry. 1997;37 (2-3) :iii.
Meltzer S, Mandler D. Studying the anodic dissolution of aluminum by the atomic force microscope (AFM). ATB Metall.ATB Metallurgie. 1997;37 (2-3-4) :289 - 294.Abstract
At. force microscope (AFM) was used to examine aluminum sample prepn., electropolishing and anodic dissoln. The anodic dissoln. of Al was studied in ammonium tartrate and sulfuric acid. Smoothening or roughening of the surface was imaged and depends primarily on the time, potential and type of electrolyte. [on SciFinder(R)]
Mandler D, Turyan I. Applications of self-assembled monolayers in electroanalytical chemistry. ElectroanalysisElectroanalysis. 1996;8 (3) :207 - 13.Abstract
A review with 69 refs. The different approaches in which self-assembled monolayers (SAMs) were applied in electroanal. chem. are reviewed. Three principal concepts were used and can be categorized according to the mechanism of attachment of the monolayer to the electrode. These include the formation of covalent bonds between reactive org. mols., such as chlorosilanes, with activated surfaces, the formation of lipid and bilayer lipid membranes that self-assemble on conductive surfaces and the adsorption of functionalized alkanes, e.g., alkanethiols, on well ordered surfaces. Systems for detecting inorg., org. and biol. species are described and conclusions are drawn. [on SciFinder(R)]
Mandler D, Meltzer S, Shohat I. Microelectrochemistry on surfaces with the scanning electrochemical microscope (SECM). Isr. J. Chem.Israel Journal of Chemistry. 1996;36 (1) :73 - 80.Abstract
A review with 23 refs. The scanning electrochem. microscope (SECM) is one of the scanning probe techniques that were developed following the introduction of the scanning tunneling microscope. The approaches that were used to modify surfaces with lateral resoln. using the SECM are presented and discussed. These approaches made it possible to drive a variety of microelectrochem. reactions on surfaces, as well as to study the mechanism of these processes due to the unique advantages that the SECM offers. [on SciFinder(R)]
Selzer Y, Mandler D. A novel approach for studying charge transfer across an interface of two immiscible solutions using the scanning electrochemical microscope (SECM). J. Electroanal. Chem.Journal of Electroanalytical Chemistry. 1996;409 (1-2) :15 - 17.Abstract
A method of scanning electrochem. microscope (SECM) was used to analyze the kinetics of the charge transfer at the liq./liq. interface. The method overcomes a limitation requiring a sepn. of ion transfer process from the charge transfer process. Few exptl. results involving iridium and iron complexes are discussed. [on SciFinder(R)]
Dakkouri AS, Kolb DM, Edelstein-Shima R, Mandler D. Scanning Tunneling Microscopy Study of L-Cysteine on Au(111). LangmuirLangmuir. 1996;12 (11) :2849 - 2852.Abstract
The adsorption of L-cysteine on Au(111) from a perchlorate soln. was studied by in-situ scanning tunneling microscopy. The potential-induced adsorption of the thiols lifts the reconstruction of Au(111) and at more pos. potentials L-cysteine adopts a definite adlayer structure. The potential-induced desorption of the adlayer does not cause the reconstruction to reappear but instead leaves a roughened surface with a large no. of monoat. high gold islands and monoat. deep holes. [on SciFinder(R)]