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Project

Super-resolution optical microscopy and optical trapping of nanoparticles in the vacuum chamber of a scanning electron microscope

In 1986, Ashkin and coworkers proposed the use of tightly focused laser beams to manipulate individual micro-scale objects such as microparticles. Typically, micro- and nano-scale objects freely diffuse in the bulk solution. In the presence of an optical field, the particles can be trapped in the focal spot as a trapping potential is generated there. When several nanoparticles are trapped, they will generate an assembly inside the focus. Recently, Prof. Masuhara’s group reported a novel optical trapping phenomenon and associated assembling mechanism in which the propagation of the trapping laser light through the assembly allows the assembly expansion outside the focal spot. The effective irradiation area is extended by multiple photon-scattering from the formed (nano/micro)-assembly. At the origin of the observed ‘larger than the focal spot-size assembly’ lays the concept coined “Optically Evolved Assembling”. Phenomenological the optically evolved assembly can be easily understood. In short, initially, some NPs are trapped at the interface and well inside the focal volume, resulting in a small assembly. The trapped NPs scatter the trapping laser, which expands the optical potential outside the focus. There, new incoming NPs join the assembly. Subsequently, the scattered laser is propagated further through the expanded assembly, enlarging the potential outside the original focal spot, and so on. The “Optically Evolved Assembling” concept is entirely new and has a lot of (practical) potential for light-induced material fabrication in the future.

Date:28 Sep 2021 →  Today
Keywords:optical trapping
Disciplines:Nanochemistry
Project type:PhD project