TY - CONF A1 - Weinel, Kristina T1 - Electron-beam induced particle synthesis: Phenomenological study of the physical mechanisms N2 - Several studies have shown that the electron beam (e-beam) can be used to create nanomaterials from microparticles in situ in a TEM. However, attempts to produce gold nanoparticles (NPs) on silicon oxide substrate remained to be accomplished. Here, we show that the production of gold NPs is possible by using the e-beam in a SEM, under a set of parameters. To understand the physical mechanisms leading to the gold NPs, the mechanisms of e-beam induced charging as well as e-beam induced heating of the MPs were discussed. Several hints point to heating as the driving mechanism. T2 - IFW Dresden, Seminar CY - Dresden, Germany DA - 06.12.2023 KW - Electron-beam-induced modification KW - Nanoparticle synthesis KW - Scanning electron microscopy KW - Driving physical mechanism KW - Negative charged microparticle KW - Temperature driven process PY - 2023 AN - OPUS4-59081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina T1 - Electron-beam-induced production of gold nanoparticles N2 - Several studies have shown that the electron beam (e-beam) can be used to create nanomaterials from microparticles in situ in a TEM. However, attempts to produce gold nanoparticles (NPs) on silicon oxide substrate remained to be accomplished. Here, we show that the production of gold NPs is possible by using the e-beam in a SEM, under a set of parameters. The NPs produced present a size gradient along the radial direction. A parameter study shows that the microparticles may: 1) flicker away without producing NPs, 2) fragment to form NPs and/or 3) react with the silicon oxide substrate, depending on the applied current. A hypothesis regarding the driving physical phenomena that lead the microparticles to fragment into NPs is discussed. Fabrication of gold NPs in the SEM provides a more cost-effective option as compared to the established method in the TEM. T2 - PhD Seminar CY - Berlin, Germany DA - 26.11.2023 KW - Electron-beam-induced modification KW - Gold nanoparticles KW - Fabrication method KW - Scanning electron microscope KW - Nano-assemblies PY - 2023 AN - OPUS4-59080 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina T1 - Plasmonic Behavior in Assemblies of Disordered Gold Nanoparticles N2 - Plasmons are collective oscillations of the free electron density in metals which can be described by an electromagnetic field. Surface plasmons are longitudinal waves propagating at the surface of the metallic material coupled to an external field. Localized surface plasmons on a nanoparticle reveal the behavior of standing waves with discrete resonance frequencies whose dominating mode is called dipole mode. Coupling of nanoparticles leads eventually to a hybridization of those dipole modes and therefore to spectral and spatial delocalization which was already investigated in ordered systems. In disordered systems, there are a lot of open questions regarding the propagation behavior which changes from delocalization to localization for instance due to the disorder. This phenomenon is then called Anderson localization. To investigate the propagation behavior of plasmonic waves in an assembly of disordered gold NPs, we combine experimental results of electron energy loss spectroscopy in a scanning transmission microscope with simulation results of the self-consistent dipole modelling. We indeed find experimentally localization of plasmon modes and with the simulation we could exclude other localization mechanism such as life-time damping or retardation. In conclusion, we could found Anderson localization of surface plasmons in assemblies of disordered gold nanoparticles which will enhance the understanding of this kind of vector waves to the Anderson localization as a general wave behavior in disordered systems. T2 - PhD seminar Leipniz Institut for solid state and material research (IFW Dresden) CY - Dresden, Germany DA - 19.06.2024 KW - Plasmonic KW - EELS in STEM KW - Self-consistent dipole model KW - Assemblies of gold nanoparticles PY - 2024 AN - OPUS4-60945 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina T1 - Heat-driven synthesis of gold nanoparticles from gold microparticles in an e-beam of an SEM N2 - The synthesis of gold nanoparticles from a microparticle precursor were done by illuminating the precursor with an e-beam in an SEM. To understand the driving physical mechanism, a model for thermodynamic calculation were set up and solved numerically. The results support not charging, but heat as the main mechanism. T2 - IFW annual PhD seminar CY - Görlitz, Germany DA - 22.10.2024 KW - Heat-driven synthesis KW - Scanning Electron Microscopy KW - Nanoparticle synthesis PY - 2024 AN - OPUS4-61834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina T1 - Electron-beam-induced synthesis and characterization of disordered plasmonic gold nanoparticle assemblies N2 - Several studies have been shown that the electron beam can be used to create nanomaterials from microparticle targets in situ in a transmission electron microscope (TEM). Here, we show how this method has to be modified in order to synthesize plasmonic gold nanoparticles (NPs) on insulating silicon oxide substrate by employing a scanning electron microscope with a comparatively low acceleration voltage of 30 kV. The synthesized NPs exhibit a random distribution around the initial microparticle target: Their average size reduces from 150 nm to 3 nm with growing distance to the initial Au microparticle target. Similarly, their average distance increases. The synthesized NP assemblies therefore show distinctly different plasmonic behaviour with growing distance to the target, which allows to study consequences of random hybridization of surface plasmon in disordered system, such as Anderson localization. To reveal the surface plasmons and their localization behaviour we apply electron energy loss spectroscopy in the TEM. T2 - DPG spring conference, condensed matter section CY - Berlin, Germany DA - 17.03.2024 KW - Scanning electron microscopy KW - Gold nanoparticle synthesis KW - Disordered assemblies KW - Localized plasmons PY - 2024 AN - OPUS4-59763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -