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  • 101.
    Zhang, Jinbao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ellis, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Yang, Lei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Vlachopoulos, Nick
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Shevchenko, Denys
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of Poly(3,4-ethylenedioxythiophene) in Solid-State Dye-Sensitized Solar Cells: Comparison of In Situ Photoelectrochemical Polymerization in Aqueous Micellar and Organic Media2015In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 87, no 7, p. 3942-3948Article in journal (Refereed)
    Abstract [en]

    Solid-state dye-sensitized solar cells (sDSCs) are devoid of such issues as electrolyte evaporation or leakage and electrode corrosion, which are typical for traditional liquid electrolyte-based DSCs. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most popular and efficient p-type conducting polymers that are used in sDSCs as a solid-state hole-transporting material. The most convenient way to deposit this insoluble polymer into the dye-sensitized mesoporous working electrode is in situ photoelectrochemical polymerization. Apparently, the structure and the physicochemical properties of the generated conducting polymer, which determine the photovoltaic performance of the corresponding solar cell, can be significantly affected by the preparation conditions. Therefore, a simple and fast analytical method that can reveal information on polymer chain length, possible chemical modifications, and impurities is strongly required for the rapid development of efficient solar energy-converting devices. In this contribution, we applied matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the analysis of PEDOT directly on sDSCs. It was found that the PEDOT generated in aqueous micellar medium possesses relatively shorter polymeric chains than the PEDOT deposited from an organic medium. Furthermore, the micellar electrolyte promotes a transformation of one of the thiophene terminal units to thiophenone. The introduction of a carbonyl group into the PEDOT molecule impedes the growth of the polymer chain and reduces the conductivity of the final polymer film. Both the simplicity of sample preparation (only application of the organic matrix onto the solar cell is needed) and the rapidity of analysis hold the promise of making MALDI MS an essential tool for the physicochemical characterization of conducting polymer-based sDSCs.

  • 102.
    Zubarev, Roman A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Damirev, Plamen A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Håkansson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Sundqvist, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Approaches and Limits for Accurate Mass Characterization of Large Biomolecules1995In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 67, no 20, p. 3793-3798p. 3793-3798Article in journal (Refereed)
    Abstract [en]

    The use of the average mass for mass characterization oflarge biomolecules is examined in light of the latestachievements in mass spectrometry, and factors affectingthe accuracy of both theoretical calculation and experimentaldetermination are analyzed. It is concluded that,in practice, the accuracy of average mass measurementsis limited to f O . l Da for molecular masses below 10 000Da and to 10 ppm for masses above that value. Inherentproperties of the isotopic distributions lead to a systematicunderestimation of the average mass during the measurements.The procedure proposed earlier (Zubarev, R A.Int. J. Mass. Spectrom. Ion Processes 1991,107,17-27) in order to correct for this effect is now extended tothe case of multiply-charged ions and their use for massscale calibration. A formula is derived for the relationshipbetween mass accuracy and both the instrumental resolvingpower and molecular ion peak statistics. Monoisotopicmass measurements are recommended to be usedwhenever possible. As a complement to that, otheradditive quantities, such as the ratio of intensities of theh t is otopic peak to the monoisotopic peak, can beemployed.

  • 103.
    Zubarev, Roman A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Håkansson, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Sundqvist, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Accuracy requirements for peptide characterization by monoisotopic molecular mass measurements1996In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 68, no 22, p. 4060-4063Article in journal (Refereed)
    Abstract [en]

    Accurately measured monoisotopic mass of a biomolecule can reveal its elemental and, in the case of a biopolymer, its monomer composition. In this work, the limitations of the technique were analyzed in application to peptides. For the currently available level of mass accuracy of about ±1 ppm, the mass limit for revealing the unique elemental composition of a peptide was found to be 700−800 Da, with the possibility to extend this range as the mass accuracy improves. As for the amino acid composition determination, the principal limit of 500−600 Da cannot be overcome in the general case by instrumental or methodological improvements. It is proposed that, for the peptide characterization, the molecular mass must be determined with sufficient accuracy to rule out a significant fraction of the peptides having the same nominal mass but different elemental and amino acid compositions. An accuracy of ±1 ppm was found to exclude 99% of such peptides and, therefore, ensure a high degree of confidence in peptide characterization.

123 101 - 103 of 103
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