Investigation Of Irradiation Effect On Gold Nanowires Induced By Heavy Ions

In the past,researchers have got a large number of results and created several models to explain the related experimental phenomenon during studying the interaction of heavy ion and bulk materials,which can explain the defects generation in bulk materials and predict the property changes of solid materials after irradiation.Nowadays,with the fast development of nanoscience,nanomaterials have permeated many fields,including ion irradiation area.As an important member of nanomaterials,one-dimensional nanomaterial has been attracted wide attention for its huge aspect ratio and small size characteristics.One-dimensional nanomaterials include nanobelt,nanospiral,nanotube and nanowire,and nanowire is the most common one.Nanowire's one-dimensional structure makes it have great application prospect in the energy transmission.Nanowire can be used in field emission,thermoelectricity and photoelectricity electronic devices and so on.Heat transmission in nanowire is different with its bulk counterpart,because heat diffusing is along all directions in bulk materials,but mainly along the long axis direction in nanowire,which extend the thermodynamic process in nanowire.The different transmission behavior of thermal energy makes the heating effect induced by incident ion in nanomaterial is different with bulk materials.Therefore,people begin to the study of heavy ion interact with nanowires and its corresponding effects.Recently,the study of irradiation effect on nanowires mainly focuses on ceramics,insulator and semiconductor nanowire,and there are few researches on metal nanowires with excellent conductivity.So,the study of heavy ion irradiation effect on gold nanowires is helpful for us to understand the basic interact process of heavy ion and metal nanowires and the influence of ion irradiation effect onthe structure if nanowire further.In this work,nanowires were prepared in heavy ion track templates(polycarbonate PC)by assisting electrochemical deposition method.The morphology and crystal structure of pristine gold nanowires were characterized by scanning electron telescope(SEM)and transmission electron telescope(TEM)get the surface and structure information.The gold nanowires were irradiated with different conditions(including different species,ion energy,irradiation dose and dose rate)at 320 k V experiment platform and heavy ion accelerator(HIRFL)in Institute of modern physics,Chinese Academy of Science.After irradiation,the morphology and structure information of irradiated gold nanowires were characterized again by SEM and TEM.By comparatively analyzing the date to evaluate the irradiation damage on gold nanowires induced by heavy ion,the damage degree difference at different irradiation condition and different diameter nanowires were provided.The low-energy heavy ions with energy between 1.4 Me V and 4 Me V can rough the nanowire surface,and generate many cavities and protrusions on gold nanowire,which are related to the spike process in the near surface.Heavy ion irradiation etched surface and sputtered nanoscale particles from gold nanowires.In addition,the damage degree was different on the nanowires with different diameter.By accounting the nanoparticles sputtered from different diameter,the size distribution of particles sputtered from nanowires in different diameter was obtained,indicating that the average size of sputtered nanoparticles increased with the nanowire diameter increasing.The phenomenon was strongly related to the adsorption energy of gold nanowire.A great number of SFTs were observed in irradiated nanowires by using HRTEM,and the size of SFT seemed to be positive correlation to the nuclear energy loss of incident heavy ions.Large bumps on the surface of gold nanowires were generated after irradiation by heavy ions with the energy of 414 Me V additionally,and bump size was in the dozens nanometer.The tetrahedron and cone shapes of created bumps were confirmed by high resolution SEM.The formation of these bumps is related to the electron energy loss of SHI in gold nanowires.Electrons in gold nanowires can be ionized and excited by impacting with SHIs,then they can pass energy to gold atoms by electron-phonon coupling.Subsequently elastic thermal spike can be formed and caused the gold melting.When molten gold recrystallize,bumps on surface of gold nanowire can be formed.