Optische manipulatie en multimodale karakterisering van nanomaterialen

Decades after Richard Feynman's seminal address, 'There's Plenty of Room at the Bottom', the precise manipulation and characterization of nanomaterials remain central to modern physical sciences and industrial engineering. From the groundbreaking synthesis of quantum dots governed by quantum confinement effects to pressing global challenges, such as particulate toxicity in consumer products, marine microplastic accumulation, and yield-limiting defects in semiconductor fabrication, mastering matter at the nanometer scale is paramount. Addressing these multifaceted challenges requires a multi-modality framework combining simultaneous visualization and dynamic manipulation to ensure complete contamination control and enable rational nanomaterial design. Particularly, light-based manipulation via laser is widely recognized and applied to many fields. However, a fundamental technological gap has long persisted between optical microscopy, which excels at real-time, spatiotemporal laser manipulation, and electron microscopy, which delivers sub-nanometer spatial resolution, structural information, and elemental spectroscopy. This doctoral thesis bridges this gap by establishing an integrated instrumental architecture and experimental workflow for correlative/integrated light and electron microscopy, spanning laser induced mechanical and chemical manipulation, customized multimodal OptofluoSEM platforms, and multimodal four-dimensional scanning transmission electron microscopy, electron energy-loss spectroscopy and micro-Raman spectroscopy. In Chapter 2, numerical modeling and experimental validation established that short-range electrostatic interactions critically govern the spatial configurations and dynamic stability of optically bound colloidal assemblies. Modulating salt concentration systematically screens electrostatic repulsion, enabling a controlled transition from far-field optical bonds to near-field subwavelength arrangements. Crucially, implementing an electric dipole approximation framework enabled multi-particle simulations at a fraction of the computational cost of Maxwell stress tensor calculations, and offered a scalable tool for non-equilibrium active self-assembly. Building upon these light-electrostatics dynamics, Chapter 3 extended optical binding to anisotropic gold nanoparticles, demonstrating that particle geometry and shape-dependent scattering cross-sections dictate optical binding modes under linearly polarized near-infrared laser irradiation. Subsequently, tuning the trapping wavelength induced dynamic rotational states and reversible transition between near-field and far-field configurations, establishing a scattering threshold for reconfigurable optically induced assembly. Translating these investigations into high-vacuum electron microscopy environments to manipulate nanomaterials with light required dedicated instrumentation engineering, as detailed in Chapter 4. This phase achieved the design, integration, and operational alignment of the 'OptoFluoSEM' platform, combining environmental scanning electron microscope with a wide-field fluorescence microscope and a focused near-infrared optical trapping laser. First, precise co-localization was confirmed via fluorescent polystyrene beads and then via electron-beam-induced cathodoluminescence. Furthermore, evaluation of vacuum containment revealed that ionic liquid thin films suffer from electron-beam-induced particle displacement, inhomogeneity of thin film and photothermal heating. To improve this, microfluidic capsule cell (K-kit) was implemented and its feasibility was validated for further nanoparticle tracking during in situ liquid-cell scanning electron microscopy imaging. In Chapter 5, focused laser beam processing achieved clean functional group removal of functionalized freestanding graphene. Interestingly, time-elapsed Raman spectroscopy demonstrated that defect-induced Raman D band suppression occurs on a faster timescale than full recovery to pristine graphene. With a multimodal correlative suite, comprising micro-Raman spectroscopy, four-dimensional scanning transmission electron microscopy, and electron energy-loss spectroscopy mapping, we further investigated the underlying laser-induced degrafting mechanisms. In summary, this research demonstrated two operational pillars and their associated multimodal characterization: (i) Optical mechanical manipulation of plasmonic particles based on optical trapping and optical binding, particularly to elucidate electrolytes- and shape-dependent interactions. Subsequently, an in situ analytical platform that couples optical trapping setup with real-time liquid-phase scanning electron microscopy imaging was investigated. (ii) Optical chemical manipulation in chemically functionalized two-dimensional materials via focused laser beam. Additionally, a correlative analytical suite that probes crystallinity, electronic states, and chemical information was demonstrated. Ultimately, these multimodal, complementary tools provide promising protocols for validating light-matter interactions at nanometer resolution.