Diameter Control And Optical Manipulation Of Carbon Nanocoils

Carbon nanocoils (CNCs) exhibit outstanding mechanical and electromagnetic properties due to their peculiar helical morphologies in addition to the excellent properties of carbon nanotubes. They are expected for uses in micro-generators for electromagnetic waves, electromagnetic absorber film, sensors and nanosized springs, etc. In recent years, extensive research has been carried out on CNCs, among which the control of the size and crystallinity of CNCs has been focused on and intensively investigated.It is necessary to prepare small sized Fe-Sn catalyst particles to fabricate CNCs with small diameters. In order to solve the problem that Fe and Sn can not be coalesced with each other in a small catalyst particle, we prepared thin SnO2 film firstly by reactive RF magnetron sputtering and then implanted Fe into the SnO2 film by ion implantation to form the Fe-Sn-O film. The small-diameter CNCs (diameter range:40-100nm) were synthesized by thermal chemical deposition. The average diameter of the synthesized CNCs is an order of magnitude smaller than that of the traditional CNCs (average diameter:500-600nm) prepared by other catalysts.The key technique for the precise manipulation of a single CNC is crucial for the applications of CNCs. In this paper, we present an investigation on the optical trapping and manipulation of a single CNC dispersed in an aqueous solution. It has been found that three-dimensional manipulation of a single CNC has been achieved. The length of a single CNC can be adjusted by increasing the power of incident laser beam because the absorbed laser energy can be changed into thermal energy in a CNC. This technology would open a novel way to assemble CNCs into useful nanodevices or the nano/micro electromechanic systems (NEMS/MEMS).In the field of surface nanotechnology, the method for transporting materials in micro and nano level is limited, which is a major difficulty in the development of this field. We have successfully realized the mass transport on a single CNC with the use of an optical tweezers system, by regulating the controlling current and the laser focus position. It is believed that CNCs can absorb laser energy and transform it into thermal energy. Then a distribution of temperature gradient is generated along the CNC, which forms thermophoretic force leading to the movement of small particles along the temperature gradient on the CNC.