Nano-contact microscopy of supracrystals

Sweetman, Adam; Goubet, Nicolas; Lekkas, I.; Pileni, Marie Paule; Moriarty, Philip

Abstract

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.

Citation

Sweetman, A., Goubet, N., Lekkas, I., Pileni, M. P., & Moriarty, P. (2015). Nano-contact microscopy of supracrystals. Beilstein Journal of Nanotechnology, 6, https://doi.org/10.3762/bjnano.6.126

• Journal Article Type: Article
• Publication Date: May 29, 2015
• Deposit Date: Feb 16, 2016
• Publicly Available Date: Feb 16, 2016
• Journal: Beilstein Journal of Nanotechnology
• Print ISSN: 2190-4286
• Electronic ISSN: 2190-4286
• Publisher: Beilstein-Institut
• Peer Reviewed: Peer Reviewed
• Volume: 6
• DOI: https://doi.org/10.3762/bjnano.6.126
• Keywords: dynamic force microscopy; nanoparticle; non-contact atomic force microscopy; point contact imaging; scanning probe microscopy; supracrystal
• Public URL: https://nottingham-repository.worktribe.com/output/751066
• Publisher URL: http://www.beilstein-journals.org/bjnano/single/articleFullText.htm?publicId=2190-4286-6-126