Abstract: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… Show more
“…We focus on the transverse X-component of the forces to explore the detailed physics behind the movement of metal NP's driven by the electron beam [13][14][15][16] .…”
Section: Resultsmentioning
confidence: 99%
“…While these techniques offer a wide range of capabilities in different size ranges, it is still difficult to deliberately manipulate objects at the atomic and nanoscale levels 12 . Recently, it has been found that an electron beam can be used to deliberately manipulate metal nanoparticles, even producing both attractive and repulsive forces 8,9,[13][14][15][16] .…”
We report time dependent calculations of attosecond and femtosecond forces imposed by a kilovolt swift electron during passage near a nanometer-sized metal particle. Contrary to expectations based on dielectric theory, which suggest that the forces should always be attractive, we find that for very close approaches, attosecond forces are repulsive, and are caused by interaction of the magnetic field of the relativistic electron with currents within even nominally non-magnetic nanoparticles. These results suggest an explanation for the observation of both attractive and repulsive nanoparticle movement during the first use ofÅngstrom-sized electron beams in electron microscopy.
“…We focus on the transverse X-component of the forces to explore the detailed physics behind the movement of metal NP's driven by the electron beam [13][14][15][16] .…”
Section: Resultsmentioning
confidence: 99%
“…While these techniques offer a wide range of capabilities in different size ranges, it is still difficult to deliberately manipulate objects at the atomic and nanoscale levels 12 . Recently, it has been found that an electron beam can be used to deliberately manipulate metal nanoparticles, even producing both attractive and repulsive forces 8,9,[13][14][15][16] .…”
We report time dependent calculations of attosecond and femtosecond forces imposed by a kilovolt swift electron during passage near a nanometer-sized metal particle. Contrary to expectations based on dielectric theory, which suggest that the forces should always be attractive, we find that for very close approaches, attosecond forces are repulsive, and are caused by interaction of the magnetic field of the relativistic electron with currents within even nominally non-magnetic nanoparticles. These results suggest an explanation for the observation of both attractive and repulsive nanoparticle movement during the first use ofÅngstrom-sized electron beams in electron microscopy.
“…The electron beam dose effects on sintering of passivated Au nanoparticles driven by surface atom diffusion rather than Ostwald ripening. 14 Zheng et al reported that high-energy electron beam can be used as a nanoscale tweezer to control nanoparticles in solution. [9][10][11][12][13] The sublimation of Ag nanoparticles with size over 20 nm was investigated by in-situ TEM under elevated temperatures, indicating the dependence on facets.…”
A sintering process of nanoparticles made of Ag, Au, and interfaced Ag/Au heterodimers was investigated by in situ transmission electron microscopy at room temperature. Such a process is driven by the illumination of a high-energy electron beam accelerated at 200 kV that promotes atom diffusion in the nanoparticles that are in physical contact. Upon electron illumination, adjacent Au nanoparticles gradually merge together to form a larger particle along with the reduction of the surface area despite the fact that orientated attachment is not observed. According to the detailed analysis of the size change of the particles and the contact area, it was found that the nanoparticle fusion process is significantly different from the well-established thermal diffusion mechanism. In addition to the similar fusion process of Au nanoparticles, Ag nanoparticles undergo apparent sublimation induced by knock on damage because the transferred energy from the electron beam to nanoparticles is higher than the surface binding energy of Ag atoms when the electron scattering angle is larger than 112°. The particles with a smaller size diffuse faster. Surface diffusion dominates at the beginning of the fusion process followed by slower lattice diffusion. Electron beam illumination can transform the interfaced Au/Ag dimers to Au@Ag core-shell particles followed by a slow removal of the Ag shells. This process under normal electron beam illumination is a lot faster than the thermally driven process. Both diffusion and sublimation of Ag atoms are dependent on the intensity of the electron beam, i.e., a higher beam intensity is favorable to accelerate both the processes.
“…Therefore, a uniform and stable liquid thin film is indispensable to practical e-beam direct-writing. K-kit (Liu et al, 2008; Tai et al, 2012; Chen et al, 2014), a liquid sample holder, was utilized in this work for achieving such a uniform liquid thin film. Figure 1 Reduction of Cu patterns from a thin CuSO 4 solution layer. a: Schematic diagram of reduction of Cu patterns from a thin CuSO 4 solution layer.…”
Section: Introductionmentioning
confidence: 99%
“…Therefore, a uniform and stable liquid thin film is indispensable to practical e-beam direct-writing. K-kit (Liu et al, 2008;Tai et al, 2012;Chen et al, 2014), a liquid sample holder, was utilized in this work for achieving such a uniform liquid thin film.…”
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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