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Michael Zharnikov - One of the best experts on this subject based on the ideXlab platform.

  • pronounced solvent effect on the composition of binary Self Assembled Monolayers with embedded dipole moments
    Journal of Physical Chemistry C, 2020
    Co-Authors: Eric Sauter, And Andreas Terfort, Michael Zharnikov
    Abstract:

    The formation and properties of binary thiolate Self-Assembled Monolayers (SAMs), comprised of precursors featuring a short heteroaromatic backbone, consisting of a nonpolar phenyl ring and a polar...

  • modification of Self Assembled Monolayers by electron irradiation the effect of primary energy 10 500 ev
    Journal of Physical Chemistry C, 2019
    Co-Authors: Martin Schmid, Xianglong Wan, Andika Asyuda, Michael Zharnikov
    Abstract:

    Well-defined alkanethiolate Self-Assembled Monolayers (SAMs) represent a useful model system for a variety of thin organic films on solid supports, in particular in the context of their modificatio...

  • orbital dependent charge transfer dynamics in conjugated Self Assembled Monolayers
    Physical Review Letters, 2011
    Co-Authors: Hicham Hamoudi, And Andreas Terfort, Stefan Neppl, Bjorn Schupbach, P Feulner, David L Allara, Michael Zharnikov
    Abstract:

    : Femtosecond charge transfer (CT) dynamics in a series of Self-Assembled Monolayers with an oligo(phenylenethynylene) and oligo(phenyl) backbone is addressed by resonant Auger spectroscopy using the core hole clock method. The characteristic CT times are found to depend strongly on the character of the molecular orbital (MO) which mediates the CT process. This demonstrates that the efficiency and rate of CT through molecular frameworks can be controlled by resonant injection of the charge carriers into specific MOs.

  • dipodal ferrocene based adsorbate molecules for Self Assembled Monolayers on gold
    Chemistry: A European Journal, 2008
    Co-Authors: Tobias Weidner, Michael Zharnikov, Nirmalya Ballav, A Priebe, Nicholas J Long, Jorg Maurer, Rainer F Winter, Alexander Rothenberger, Dieter Fenske, Dag Rother
    Abstract:

    : 1,1'-Difunctionalised ferrocene derivatives have been studied, which contain groups suitable for chemisorption on gold substrates, namely -NC, -PR(2) as well as a range of sulfur-containing units like -NCS, -SR, and thienyl. Thin films on gold have been fabricated from solution with most of these adsorbate species. Film thickness, composition and structure were investigated primarily by X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy. The quality of Self-Assembled Monolayers fabricated from 1,1'-diisocyanoferrocene (1) and 1,1'-diisothiocyanatoferrocene (2) turned out to be superior to that of films based on the other adsorbate species investigated. In addition to the surface coordination behaviour of 1 towards gold substrates, relevant aspects of the molecular coordination chemistry of 1 have also been addressed, including the synthesis and characterisation of [(mu-1){Cr(CO)(5)}(2)], [Ag(2)(mu-1)(2)](NO(3))(2) x H(2)O and [(mu-1)(AuCl)(2)]. The crystal structure of the gold complex is governed by aurophilic interactions and can be taken as a model for the arrangement of 1 in Self-Assembled Monolayers on gold.

  • balance of structure building forces in selenium based Self Assembled Monolayers
    Journal of the American Chemical Society, 2007
    Co-Authors: Andrey Shaporenko, And Andreas Terfort, Tobias Weidner, Jan Müller, Michael Zharnikov
    Abstract:

    Using a model system of 4,4‘-biphenyl-substituted alkaneselenols on (111) gold and silver substrates, we show that the hybridization and, thus, spatial orientation of the binding orbitals of selenium is a determining factor for the molecular packing and structure of alkaneselenolate Self-Assembled Monolayers (SAMs). Considering that a similar effect has been previously observed for the sulfur headgroup in alkanethiolate SAMs, its generality for different SAM systems can be assumed.

Takeo Ohsaka - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous Electroanalysis of Ascorbic Acid, Dihydroxyphenylacetic Acid, Homovanillic Acid and Uric Acid Using Gold Electrode Modified with Cationic Self-Assembled Monolayers
    Chemistry Letters, 2001
    Co-Authors: Chellappan Retna Raj, Takeo Ohsaka
    Abstract:

    Cationic Self-Assembled Monolayers (SAMs) of cystamine (CYST) and dithiobishexaneamine (DTH) are utilized for the simultaneous electroanalysis of four different anions, ascorbic acid (AA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and uric acid (UA).

  • electroanalytical applications of cationic Self Assembled Monolayers square wave voltammetric determination of dopamine and ascorbate
    Bioelectrochemistry, 2001
    Co-Authors: Koichi Tokuda, Takeo Ohsaka
    Abstract:

    Abstract Gold electrodes modified with cationic Self-Assembled Monolayers (SAMs) of 2,2′-dithiobisethaneamine (CYST) and 6,6′-dithiobishexaneamine (DTH) were used for the simultaneous determination of dopamine (DA) and ascorbate (AA). The cationic SAM modified electrodes have several advantages over the bare electrode for the oxidation of AA. A very large (∼450 mV) decrease in the overpotential for the oxidation of AA when compared with the bare electrode has been observed at the cationic monolayer-modified electrode. The electrostatic interaction of negatively charged AA with the monolayer shift the oxidation peak potential of AA to less positive potential and enhances the peak current. On the other hand, the positively charged DA is repelled from the monolayer and the oxidation potential shifts to more positive potential when compared to the bare electrode. The electrochemical oxidation of AA at the mixed monolayer of CYST and diethyl disulfide (DEDS) supports the influence of cationic terminal group of the monolayer on the oxidation of AA. Since the oxidation of AA occurs well before the oxidation potential of DA is reached, the homogeneous catalytic oxidation of AA by the oxidized DA has been advantageously eliminated at the monolayer-modified electrode. The cationic Self-Assembled Monolayers successfully detect DA in the presence of high concentration of AA. The sensitivity of the electrode modified with CYST monolayer was found to be 0.036 and 0.021 μA/μM towards AA and DA, respectively.

  • electroanalytical applications of cationic Self Assembled Monolayers square wave voltammetric determination of dopamine and ascorbate
    Bioelectrochemistry, 2001
    Co-Authors: Chellappan Retna Raj, Koichi Tokuda, Takeo Ohsaka
    Abstract:

    Gold electrodes modified with cationic Self-Assembled Monolayers (SAMs) of 2,2'-dithiobisethaneamine (CYST) and 6,6'-dithiobishexaneamine (DTH) were used for the simultaneous determination of dopamine (DA) and ascorbate (AA). The cationic SAM modified electrodes have several advantages over the bare electrode for the oxidation of AA. A very large (approximately 450 mV) decrease in the overpotential for the oxidation of AA when compared with the bare electrode has been observed at the cationic monolayer-modified electrode. The electrostatic interaction of negatively charged AA with the monolayer shift the oxidation peak potential of AA to less positive potential and enhances the peak current. On the other hand, the positively charged DA is repelled from the monolayer and the oxidation potential shifts to more positive potential when compared to the bare electrode. The electrochemical oxidation of AA at the mixed monolayer of CYST and diethyl disulfide (DEDS) supports the influence of cationic terminal group of the monolayer on the oxidation of AA. Since the oxidation of AA occurs well before the oxidation potential of DA is reached, the homogeneous catalytic oxidation of AA by the oxidized DA has been advantageously eliminated at the monolayer-modified electrode. The cationic Self-Assembled Monolayers successfully detect DA in the presence of high concentration of AA. The sensitivity of the electrode modified with CYST monolayer was found to be 0.036 and 0.021 microA/microM towards AA and DA, respectively.

Shaoyi Jiang - One of the best experts on this subject based on the ideXlab platform.

Randall T Lee - One of the best experts on this subject based on the ideXlab platform.

  • Stability of Aliphatic Dithiocarboxylic Acid Self-Assembled Monolayers on Gold
    2020
    Co-Authors: Tai-chou Lee, Donna J Hounihan, Ramon Colorado, Joon-seo Park, Randall T Lee
    Abstract:

    Self-Assembled Monolayers (SAMs) were prepared by the adsorption of aliphatic dithiocarboxylic acids (ADTCAs) onto the surface of gold. The films were characterized using a variety of analytical techniques: ellipsometry, contact angle goniometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). These studies found that the ADTCAs attach to the surface of gold via equivalent binding of both sulfur moieties in the dithiocarboxylic acid headgroup. The stability of these highly orientated SAMs was examined at room temperature under a variety of atmospheric conditions (i.e., under argon, oxygen, air, and humid air) and compared to the stability of related SAMs derived from n-alkanethiols. The ADTCA-based SAMs were observed to decompose relatively rapidly via oxidation of the sulfur headgroups, as judged by XPS. The rate of desorption of the SAMs was observed to vary as a function of the atmospheric conditions as well as the chain length of the ADTCA adsorbates

  • stability of aliphatic dithiocarboxylic acid Self Assembled Monolayers on gold
    Journal of Physical Chemistry B, 2004
    Co-Authors: Tai-chou Lee, Donna J Hounihan, Ramon Colorado, And Joonseo Park, Randall T Lee
    Abstract:

    Self-Assembled Monolayers (SAMs) were prepared by the adsorption of aliphatic dithiocarboxylic acids (ADTCAs) onto the surface of gold. The films were characterized using a variety of analytical te...

J P Ferraris - One of the best experts on this subject based on the ideXlab platform.

  • controlling charge injection in organic electronic devices using Self Assembled Monolayers
    Applied Physics Letters, 1997
    Co-Authors: I H Campbell, J D Kress, Richard L Martin, D L Smith, N N Barashkov, J P Ferraris
    Abstract:

    We demonstrate control and improvement of charge injection in organic electronic devices by utilizing Self-Assembled Monolayers (SAMs) to manipulate the Schottky energy barrier between a metal electrode and the organic electronic material. Hole injection from Cu electrodes into the electroluminescent conjugated polymer poly[2-methoxy,5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] was varied by using two conjugated-thiol based SAMs. The chemically modified electrodes were incorporated in organic diode structures and changes in the metal/polymer Schottky energy barriers and current–voltage characteristics were measured. Decreasing (increasing) the Schottky energy barrier improves (degrades) charge injection into the polymer.

  • controlling schottky energy barriers in organic electronic devices using Self Assembled Monolayers
    Physical Review B, 1996
    Co-Authors: I H Campbell, J D Kress, Richard L Martin, D L Smith, N N Barashkov, Shai Rubin, Thomas A Zawodzinski, J P Ferraris
    Abstract:

    We demonstrate tuning of Schottky energy barriers in organic electronic devices by utilizing chemically tailored electrodes. The Schottky energy barrier of Ag on poly[2-methoxy], 5-(2{prime}-ethyl-hexyloxy)- 1,4-phenylene was tuned over a range of more than 1 eV by using Self-Assembled Monolayers (SAM{close_quote}s) to attach oriented dipole layers to the Ag prior to device fabrication. Kelvin probe measurements were used to determine the effect of the SAM{close_quote}s on the Ag surface potential. {ital Ab} {ital initio} Hartree-Fock calculations of the molecular dipole moments successfully describe the surface potential changes. The chemically tailored electrodes were then incorporated in organic diode structures and changes in the metal/organic Schottky energy barriers were measured using an electroabsorption technique. These results demonstrate the use of Self-Assembled Monolayers to control metal/organic interfacial electronic properties. They establish a physical principle for manipulating the relative energy levels between two materials and demonstrate an approach to improve metal/organic contacts in organic electronic devices. {copyright} {ital 1996 The American Physical Society.}