Browsing by Subject "Transmission Electron Microscopy"

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    ItemOpen Access
    Synthesization of noble metal nanoparticles by pulsed laser ablation method in liquids and thin film applications
    (2012) Vural, Hüseyin Avni
    Pulsed Laser Ablation in Liquid (PLAL) is promising, alternative, easy, fast and free of agent method for synthesization of nanoparticles (NPs). Various kinds of NPs can be synthesized easily by PLAL, such as base metals, noble metals, semiconductors, nanoalloys, magnetic and core–shell nanostructures. Additionally, crystallized NPs can be easily obtained in one-step procedure by PLAL without subsequent heat-treatments. Synthesization of gold (Au), silver (Ag) and platinum (Pt) NPs with PLAL using Nd: YLF laser (Q-Switched Laser, 527 nm wavelength, 16 W average power, 110 ns pulse duration, and 16 mJ pulse energy for 1 kHz) in different liquid environments is reported. Firstly, Ag, Au and Pt NPs have been synthesized with pulsed Nd: YLF laser in deionized water. Secondly, these NPs have been synthesized in methanol under similar conditions. Colloidal NP solutions are then characterized with Transmission Electron Microscopy, Scanning Electron Microscopy, X-Ray Photoelectron Spectrophotometer, X-Ray Diffractometer and UV-Vis Photospectrometer analysis techniques.In the second part, applications of noble metal nanoparticles have been investigated. Firstly, Au and Ag NPs have been synthesized in Polyvinylpyrolidone solution in order to prepare nanofibrous composites. The Au and Ag NPs embedded in nanofibrous composites then characterized with UV-Vis Photospectrometer and Transmission Electron Microscopy. In addition, AuNPs have been synthesized with varying energies of laser (9,2 mJ, 12 mJ and 16 mJ for 1kHz) in order to understand the role of laser energy on PLAL. Finally, thin-film applications also presented: Pulsed Laser Deposition by PLAL and simple spin-coating deposition with AuNPs synthesized in methanol.
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    ItemOpen Access
    Tunable White-Light-Emitting Mn-Doped ZnSe Nanocrystals
    (American Chemical Society, 2014-02-06) Sharma, V. K.; Guzelturk, B.; Erdem, T.; Kelestemur, Y.; Demir, Hilmi Volkan
    We report white-light-emitting Mn-doped ZnSe nanocrystals (NCs) that are synthesized using modified nucleation doping strategy. Tailoring three distinct emission mechanisms in these NCs, which are MnSe-related blue emission (410 and 435 nm), Zn-related defect state green emission (520 nm), and Mn-dopant related orange emission (580 nm), allowed us to achieve excitation wavelength tailorable white-light generation as studied by steady state and time-resolved fluorescence spectroscopy. These NCs will be promising as single component white-light engines for solid-state lighting.