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Title: Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C{sub 61}-butyric acid methyl ester

We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surface topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of “molecular terraces” whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction.
Authors:
;  [1] ; ; ;  [2] ; ;  [3]
  1. National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom)
  2. Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom)
  3. Department of Materials Science, Imperial College London, London SW7 2AZ (United Kingdom)
Publication Date:
OSTI Identifier:
22489418
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 5; Other Information: (c) 2016 Crown; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC FORCE MICROSCOPY; BUTYRIC ACID; ESTERS; INTERFEROMETERS; LASERS; LATTICE PARAMETERS; MATHEMATICAL SOLUTIONS; MICROSCOPES; MIRRORS; MONOCRYSTALS; RESOLUTION; SOLVENTS; SUBSTRATES; SURFACES; TOPOGRAPHY; WAVELENGTHS; X-RAY DIFFRACTION