Sarah Hoppe Pratt

Time-Resolved 3D Imaging of Ion Beam Induced Surface Damage in Gold Nanoparticles

Many properties of nanoparticles (NPs) are closely tied to their size, shape, surface, and internal structures [1, 2]. Different synthesis methods can produce an array of NP sizes and shapes, but it is also desirable to have methods to modify existing NPs. Extensive research on ion beam induced surface modification of bulk materials [3] has led to a strong understanding of ion-solid interactions, and positioned ion beams as promising tools for modifying NPs. However, fewer studies have explored the effects that these energetic ions have on nanomaterials [4, 5]. Electron tomography is a useful tool for exploring the 3D shape of small structures, and can be applied to study ion beam induced structural modification in NPs. While general trends in NP shape evolution during ion bombardment can be obtained by ex situ irradiation followed by microscopy, such techniques cannot reliably track the evolution of individual particles. Additionally, diffusion may obscure subtle details of surface structures and sputtered material left immediately following an ion collision before it is possible to observe the specimen. In situ ion irradiation TEM addresses this issue by allowing nanometer-scale observation of samples in real time during bombardment by a variety of ion species and energies. By combining in situ irradiation and electron tomography techniques, samples can be continually monitored for changes, then immediately examined in greater depth when such changes occur.