Chemistry / Kimya

Permanent URI for this collectionhttps://hdl.handle.net/11147/4072

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Access type: Open accessAuthor: search.filters.author.Cölfen, Helmut

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  • Book Part
    Citation - Scopus: 8
    The Multiwavelength Uv/Vis Detector: New Possibilities With an Added Spectral Dimension
    (Springer Verlag, 2016) Karabudak, Engin; Cölfen, Helmut
    The multiwavelength (MWL) detector is a new type of absorption detector for AUC. The commercial absorption detector of the Beckman Coulter XLA AUC can only handle a single wavelength per scan with the possibility to scan at maximum 3 wavelengths, whereas MWL-AUC can handle all the wavelengths in the UV/Vis region at one time. The result is impressive since now a full spectral dimension is added to each single scan. In this chapter, we are explaining development history, instrumentation, and future perspective of MWL-AUC.
  • Article
    Citation - WoS: 47
    Citation - Scopus: 49
    Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution With Subnanometer Resolution
    (John Wiley and Sons Inc., 2016) Karabudak, Engin; Brookes, Emre; Lesnyak, Vladimir; Gaponik, Nikolai; Eychmüller, Alexander; Walter, Johannes; Segets, Doris; Peukert, Wolfgang; Wohlleben, Wendel; Demeler, Borries; Cölfen, Helmut
    We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.