Browsing Journal Articles by Author "Ngumbi, Paul K."

Browsing Journal Articles by Author "Ngumbi, Paul K."

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  • Correlation of optical transmittance with number of graphene layers 
    John, Benjamin M.; Mugo, Simon W.; Timonah, Nelson S.; Ngumbi, Paul K.; Ngei, K. (American Institute of Physics, 2016)
    Optical transmittance of exfoliated multilayer graphene (MLG) was investigated and cross-referenced with a monolayer purchased from Graphene Supermarket USA, #Y060515. The transmittance was found ...
  • Determination of graphene layers by optical imaging contrast analysis 
    John, Benjamin M.; Ngumbi, Paul K.; Katumo, Ngei; Mugo, Simon W.; Timonah, Nelson S.; Ngaruiya, James M. (2015)
    Practical application of graphene require accurate determination of the number of layers. In this paper we demonstrate a reliable and efficient approach for determining the number of graphene layers. Plots of contrast ...
  • Graphene supported platinum counter electrode for dye sensitized solar cells 
    John, Benjamin M.; Katumo, Ngei; Mugo, Simon W.; Ngaruiya, James M.; Ngumbi, Paul K. (2015)
    A Platinum (Pt) film was prepared on graphene-fluorine-doped tin oxide (FTO) substrate through doctor blade procedure and investigated as a counter electrode (CE) for dye sensitized solar cells (DSSCs). Dye loading of ...
  • Multiple plasmon resonances in small-sized citrate reduced gold nanoparticles 
    Ngumbi, Paul K.; Mugo, Simon W.; Ngaruiya, James M.; King’ondu, Cecil K. (Elsevier, 2019-05-15)
    Metallic nanoparticles exhibit localized surface plasmon resonances resulting from the coherent oscillation of free electrons in response to electric field from incident electromagnetic radiation. In this work, the dependence ...
  • Optical conductivity of single layer graphene from experimental measurements and theoretical calculations 
    John, Benjamin M.; Ngumbi, Paul K.; Mugo, Simon W.; Ngaruiya, James M.; King’ondu, Cecil K.; Ngei, K. (AIP Publishing, 2016-12)
    With the fast growing research and applications of graphene in photonics, understanding its properties and their correlation over broad spectral range is essential. The study presented herein is an analysis of optical ...

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