"Electron Tweezers" as a Tool for In-situ Manipulation and Processing of Individual Metal Nanoparticles in a Two-Phase Partially Molten Alloy

Abstract

Vladimir P. Oleshko and James M. Howe University of Virginia, Department of Materials Science & Engineering, Charlottesville, VA 22904 Understanding physical principles for controlling the dynamic behavior of nanoparticles in inhomogeneous gas (liquid) – solid systems is becoming increasingly important for nanoscience and technology. Nondestructive trapping of micron- and nano-sized dielectric and metal particles in a liquid using a laser beam, which is refracted by the particle and transfers momentum to it, is known as a single-beam gradient force optical trap, or optical tweezers [1]. Recent experiments utilizing partially molten submicron-sized Al-Si alloy spheres and a focused electron beams in a medium-voltage TEM [2] and theoretical calculations of linear and angular momentum transfer from an electron beam to small particles [3] indicate that optical trapping of particles using electron beams may occur. Such thermally assisted “electron tweezers” potentially can be utilized for manipulation and processing of individual nanoobjects and fabrication of assembled nanodevices with up to atomic level sensitivity and lateral resolution provided by modern electron optical systems. In this work, we demonstrate electron-beam trapping of solid nanoparticles inside opaque submicron-sized Al-Si alloy spheres using energy filtering TEM (EFTEM) and parallel electron energy-loss spectroscopy (PEELS). Thermally assisted motion of crystalline Al nanospheres confined within the partially molten Al-Si particles was initiated by the electron beam, which was used to control and to observe the trapping in real-time by plasmon spectroscopic imaging (Fig. 1). Such approaches enable