Nano-contact microscopy of supracrystals

Sweetman, Adam and Goubet, Nicolas and Lekkas, I. and Pileni, Marie Paule and Moriarty, Philip (2015) Nano-contact microscopy of supracrystals. Beilstein Journal of Nanotechnology, 6 . pp. 1229-1236. ISSN 2190-4286

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Background: Highly ordered three-dimensional colloidal crystals (supracrystals) comprised of 7.4 nm diameter Au nanocrystals (with a 5% size dispersion) have been imaged and analysed using a combination of scanning tunnelling microscopy and dynamic force microscopy.

Results: By exploring the evolution of both the force and tunnel current with respect to tip–sample separation, we arrive at the surprising finding that single nanocrystal resolution is readily obtained in tunnelling microscopy images acquired more than 1 nm into the repulsive (i.e., positive force) regime of the probe–nanocrystal interaction potential. Constant height force microscopy has been used to map tip–sample interactions in this regime, revealing inhomogeneities which arise from the convolution of the tip structure with the ligand distribution at the nanocrystal surface.

Conclusion: Our combined STM–AFM measurements show that the contrast mechanism underpinning high resolution imaging of nanoparticle supracrystals involves a form of nanoscale contact imaging, rather than the through-vacuum tunnelling which underpins traditional tunnelling microscopy and spectroscopy.

Item Type: Article
Keywords: dynamic force microscopy; nanoparticle; non-contact atomic force microscopy; point contact imaging; scanning probe microscopy; supracrystal
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Physics and Astronomy
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Depositing User: Hatton, Mrs Kirsty
Date Deposited: 16 Feb 2016 09:02
Last Modified: 16 Sep 2016 17:14

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