Supplemental information
Nonylphenol polyethoxylate coated BCC-iron nanocrystals
for ferrofluids with technical applications
D. Ortega*1, N. Pérez2, J. L. Vilas2, J. S. Garitaonandia3, K. Suzuki4, J. R. Marín2 and M.
Rodríguez2
1
Dept. of Physics and Astronomy, University College London, Gower Street WC1E 6BT
London, UK
2
3
4
Kimika Fisikoa Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko
Unibertsitatea, Bilbao, Spain
Fiska Aplikatua II Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko
Unibertsitatea, Bilbao, Spain
Department of Materials Engineering, Monash University, Melbourne, Australia
Electron microscopy: processing of experimental images and simulations.
For their observation, NPs were re-suspended in excess of hexane under sonication and deposited onto
holey-carbon copper TEM grids, which were subsequently covered to avoid contamination and
allowed to dry at 30 ºC in a heater for 24 hours. This procedure ensures a good dispersion and fixation
of NPs on the carbon film while minimizing the sample drift under the electron beam due to solvent
evaporation. Digital diffraction patterns (DDPs) obtained from experimental HRTEM images
correspond to the log-scaled power spectrum of the Fourier transform of the intensity distribution in
the images. These DDPs allow measuring the associated lattice fringe spacings and angles by pointing
the intensity maximum in the diffraction spots. Identification of crystalline phases has been carried
out using the software package EJEZ developed by J. A. Pérez-Omil et al1, departing from the
available crystallographic data for iron and computing the correlation between the experimental
interplanar spacings and angles obtained from DDPs. Calculations have been made establishing
numerical tolerances of 0.30 Å for spacings and 3.00 degrees for angles. Simulations of HRTEM
images have been calculated using the multislice method2, which assumes that the samples are divided
into thin slices normal to the incident electron beam and the final surface wavefunction formed by
propagating the electron wavefunction through such slices.
Figure S1. Set of HRTEM simulations corresponding to Fig. 3c under the [001] zone axis of iron
performed for a range of thickness-defocus combinations at 200 kV.
Figure S2. Set of HRTEM simulations corresponding to Fig. 3d under the [111] zone axis of iron
performed for a range of thickness-defocus combinations at 200 kV.
References
1
2
S. Bernal, F. Botana, J. Calvino, C. Lopez-Cartes, J. Perez-Omil, and J. RodriguezIzquierdo, Ultramicroscopy 72, 135 (1998).
E. J. Kirkland, Advanced computing in electron microscopy (Springer Verlag, 2010).