2D and 3D Characterization of Plasmonic and Porous Nanoparticles using Transmission Electron Microscopy.
28 February 2018
Campus Groenenborger, U0.25 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger
Organization / co-organization:
Department of Physics
Public defence of the PhD thesis of Mr. Kadir Sentosun - Faculty of Science - Department of Physics
Plasmonic, porous nanoparticles and their combined plasmonic-porous hybrid forms have attracted high interest during the last years, due to their unique properties interesting for numerous applications in different fields ranging from biomedicine to optoelectronics. Since the properties of nanostructures are closely related to their structure and morphology, it is of key importance to obtain a detailed structural characterization. Transmission electron microscopy (TEM) is one of the most suitable characterization techniques to investigate nanomaterials at the nanometer scale and below. The images acquired using a TEM however only represent a two dimensional (2D) projection of a three dimensional (3D) object. To overcome this limitation, electron tomography is required. Although, the technique has progressed significantly the last decade, the 3D characterization of plasmonic and porous nanoparticles remains challenging. The growing interest in plasmonic nanoparticles requires clear knowledge on both the shape and structure of the nanoparticles in 3D. Therefore, need for nano and atomic scale electron tomography emerges.
Characterization of core–shell type nanoparticles made of plasmonic core and porous shell in 3D by TEM can be very challenging. Especially, when both heavy and light elements coexist within the same nanostructure, artifacts in the 3D reconstruction are often present. To obtain a reliable 3D characterization of such an object, optimization of data acquisition and reconstruction procedure of electron tomography is required.
Finally, several reasons, such as electron beam sensitivity of investigated nanostructure, hamper the acquisition of electron tomography tilt series with a large number of projection images, which deteriorate the quality of the 3D reconstruction. An inpainting method that is based on sinogram interpolation is proposed, which enables one to reduce artifacts in the reconstruction related to a limited tilt series of projection images. In my dissertation, different advanced transmission electron microscopy techniques are developed and optimized to tackle these challenges.