AFM Based Manipulation And Scattering Spectral Characterization By Dark Field Microscopy Of Nanostructure

Metal nanoparticles have the merits of stable physical and chemical properties,good biocompatibility,mature preparation technology,etc.Metal nanostructures of mesoscopic size consist of metal nanoparticles possess significant light control ability which based on the local surface plasmon resonance effect.This effect can induce near field enhancement and light conduction,which is widely used in single molecule detection,super resolution imaging,nanometer measurement,biological sensing,etc.This effect can produce light absorption and scattering.Metal nanostructures with of different geometric size can produce different absorption and scattering effects,thus it is of great significance to realize the controllable processing of metal nanometer structure and scattering light characterization of different metal nanostructures.For near-field enhancement effect produced by local plasmon resonance scattering of metal nanostructures,field enhancement effect of metal nanostructures with different geometric parameters was studied by finite element method based on COMSOL software and electromagnetic field theory in this paper.A conclusion could be drew that geometric parameter of metal nanostructures is one of the key factors which affect near-field enhancement.For metal nanostructure processing aspect,gold nanorods were trial-produced by seed growth method.Silver nanowires were chose as processing object.Controllable processing means of silver nanowire structure was explored in this paper.A series of manipulation include cutting,bending and pushing of silver nanowires were carried on using nanolithography function of atomic force microscope.Any geometric dimension of sub-wavelength silver nanowire structures could be constructed.For the drift error of atomic force microscope in the process of manipulation,manipulation error experiment was carried out and the experimental results and error sources were analyzed,which provided an experimental basis in improving manipulation efficiency and precision.Finally,sub-wavelength single silver nanowire and single "L" type of silver nanowire structure were obtained through manipulation function of atomic force microscope.Scattering spectral characterization of metal nanostructures was realized based on the method of dark field microscopy imaging.Dark field scattering spectrum measuring system was designed and built.Scattering spectrum of the gap of two close-distance approximate parallel nanowires was tested to verify the reliability of the system.Scattering spectrum of single silver nanowire and single "L" type of silver nanowire structure was tested by the dark field measuring system.A conclusion could be drew that differences of scattering spectrum can preliminarily distinguish silver nanowire structures of different geometric size.