The electron beam (e-beam) of transmission electron microscopy (TEM) was utilized for in situ synthesizing and manipulating Au nanoparticles with various sizes in HAuCl 4 aqueous solution. The driving force for e-beam manipulation was found to be a function of particleto-beam distance, mostly due to the electric force. From experimental observations, it was concluded that the e-beam can attract the Au nanoparticles in the HAuCl 4 solution. This contributes to the dipole induced in the Au nanoparticle, which is attributed to the non-uniform positive potential built inside the observation window. On the other hand, this positive potential would induce a repulsion force with the positively charged Au nanoparticle. Therefore, repulsion behaviour of the Au nanoparticle induced by the e-beam was also observed.
ExperimentalA liquid cell named K-kit, 16 as shown in Fig. 1A, was employed as a specimen holder and the manipulation platform in TEM. The fabrication process of K-kit has been described in detail
Transmission electron microscopy (TEM) is a unique and powerful tool for observation of nanoparticles. However, due to the uneven spatial distribution of particles conventionally dried on copper grids, TEM is rarely employed to evaluate the spatial distribution of nanoparticles in aqueous solutions. Here, we present a microchip nanopipet with a narrow chamber width for sorting nanoparticles from blood and preventing the aggregation of the particles during the drying process, enabling quantitative analysis of their aggregation/agglomeration states and the particle concentration in aqueous solutions. This microchip is adaptable to all commercial TEM holders. Such a nanopipet proves to be a simple and convenient sampling device for TEM image-based quantitative characterization.
We demonstrate direct electron beam writing of a nano-scale Cu pattern on a surface with a thin aqueous layer of CuSO4 solution. Electron beams are highly maneuverable down to nano-scales. Aqueous solutions facilitate a plentiful metal ion supply for practical industrial applications, which may require continued reliable writing of sophisticated patterns. A thin aqueous layer on a surface helps to confine the writing on the surface. For this demonstration, liquid sample holder (K-kit) for transmission electron microscope (TEM) was employed to form a sealed space in a TEM. The aqueous CuSO4 solution inside the sample holder was allowed to partially dry until a uniform thin layer was left on the surface. The electron beam thus reduced Cu ions in the solution to form the desired patterns. Furthermore, the influence of e-beam exposure time and CuSO4(aq) concentration on the Cu reduction was studied in this work. Two growth stages of Cu were shown in the plot of Cu thickness versus e-beam exposure time. The measured Cu reduction rate was found to be proportional to the CuSO4(aq) concentration.
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