Bridging the gap: 3D real-space characterization of colloidal assemblies via FIB-SEM tomography

Abstract

† Electronic Supplementary Information (ESI) available: Movies S1-12 show the transmission electron tomography, FIB-SEM tomography and confocal microscopy data stacks and 3D reconstructions. Figures S1-4 give additional information on our image processing methods and show extra electron tomography data. SeeInsight in the structure of nanoparticle assemblies up to a single particle level is key to understand the collective properties of these assemblies, which critically depend on the individual particle positions and orientations. However, the characterization of large, micron sized assemblies containing small, 10-500 nanometer, sized colloids is highly challenging and cannot easily be done with the conventional light, electron or X-ray microscopy techniques. Here, we demonstrate that focused ion beam-scanning electron microscopy (FIB-SEM) tomography in combination with image processing enables quantitative real-space studies of ordered and disordered particle assemblies too large for conventional transmission electron tomography, containing particles too small for confocal microscopy. First, we demonstrate the high resolution structural analysis of spherical nanoparticle assemblies, containing small anisotropic gold nanoparticles. Herein, FIB-SEM tomography allows the characterization of assembly dimensions which are inaccessible to conventional transmission electron microscopy. Next, we show that FIB-SEM tomography is capable of characterizing much larger ordered and disordered assemblies containing silica colloids with a diameter close to the resolution limit of confocal microscopes. We determined both the position and the orientation of each individual (nano)particle in the assemblies by using recently developed particle tracking routines. Such high precision structural information is essential in the understanding and design of the collective properties of new nanoparticle based materials and processes. arXiv:1903.09989v1 [cond-mat.soft]

3D test sample for the calibration and quality control of super-resolution and confocal microscopes

“…In the direction of crystal growth (Y in Figure 1c) the distance to the nearest neighbor was ∼4% smaller than in the two other nearest neighbor directions of the hexagon. This is in agreement with earlier studies using X-ray diffraction and FIB-SEM tomography where a similar crystal growth method was used 26,28 . This slightly anisotropic deformation of the close-packed layers is almost certainly caused by the strong capillary forces between the drying liquid and the particles and the orientation of the layers with respect to the drying front.…”

“…To characterize the structure of the sample, a crystal grown using the same method, but with slightly larger particles was imaged using focused ion beam scanning electron microscopy (FIB-SEM) tomography 25,26 (see Supplementary Note 1). From the recorded FIB-SEM data the coordinates of the particles were determined, as described in ref.…”

“…From the recorded FIB-SEM data the coordinates of the particles were determined, as described in ref. 26. From the coordinates we could identify the crystal structure as face-centered cubic (FCC) with stacking faults of hexagonal close-packed (HCP) order using bond orientational order parameters 27 .…”

Gold/Silica Particles for Various Applications in (CLEM) Microscopy

“…The coordinates of the particles in the crystal were determined from the FIB-SEM tomogram as described in ref. [146].…”

“…The raw data was processed for optimal particle identification. Next, the coordinates of the particles were determined using recently developed particle tracking routines as described by van Hoeven et al [146]. From the coordinates of the particles it was possible to identify the crystal structure of the colloidal crystal using bond orientation order parameters [154], see figure 5.6b and c. The colloidal crystal structure was found to be face-centered cubic (FCC) with hexagonal close-packed (HCP) stacking faults.…”