1,721,485 research outputs found
Charoite, as an example of a structure with natural nanotubes
No full textCharoite from the Murun massif in Yakutiya, Russia (Vorob'ev 2008) was investigated using automated electron diffraction tomography (ADT) (Kolb et al. 2007, 2008; Mugnaioli et al. 2010) and precession electron diffraction (PED) (Mugnaioli et al. 2010, 2009), which allowed to determine the structure of charoite for the first time. The structure was solved ab initio in space group P21/m by direct methods using a fully kinematic approach. The least squares refinements with 2878 reflections F(hkl) >4sF converged to unweighted/weighted residuals R1/wR2 • 0.173/0.21 (Rozhdestvenskaya et al. 2010). © 2012 Springer-Verlag Berlin Heidelberg. All rights are reserved
Applications of automated diffraction tomography (ADT) on nanocrystalline porous materials
No full textMany porous materials, both inorganic and hybrid organic-inorganic, can only be synthesized as nanocrystals. X-ray powder diffraction delivers one-dimensional data from the overall sample and is therefore often limited by peak overlap at low or medium resolution and by peak broadening. Thus, structure solution of materials with large unit cells and low symmetry, disorder or pseudosymmetry, or available only in polyphasic systems, turns out to be problematic or even impossible. Electron diffraction allows collecting three-dimensional structure information from nanocrystalline materials, but is traditionally biased by low completeness of the diffraction data, dynamical scattering and beam damage. Recently, these limits have been significantly reduced by the development of automated diffraction tomography, a new method for electron diffraction data acquisition and analysis. In this paper we present several ab initio structure determinations of porous materials based on automated diffraction tomography data from single nano crystals. The possibility of collecting data sets of high completeness allows resolving the position of light atoms like oxygen and carbon. The impact of missing information caused by the missing cone effect, preferred orientation or residual beam damage for hybrid materials will be discussed. (C) 2012 Elsevier Inc. All rights reserved. RI Mugnaioli, Enrico/E-6237-201
"Ab initio" structure solution from electron diffraction data obtained by a combination of automated diffraction tomography and precession technique
No full textUsing a combination of our recently developed automated diffraction tomography (ADT) module with precession electron technique (PED), quasi-kinematical 3D diffraction data sets of an inorganic salt (BaSO(4)) were collected. The lattice cell parameters and their orientation within the data sets were found automatically. The extracted intensities were used for "ab initio" structure analysis by direct methods. The data set covered almost the complete set of possible symmetrically equivalent reflections for an orthorhombic structure. The structure solution in one step delivered all heavy (Ba, S) as well as light atoms (O). Results of the structure solution using direct methods, charge flipping and maximum entropy algorithms as well as structure refinement for three different 3D electron diffraction data sets were presented. (C) 2009 Elsevier B.V. All rights reserved. RI Kolb, Ute/A-2642-2011; Mugnaioli, Enrico/E-6237-201
3D electron diffraction applied to complex nanoparticles and nanominerals
No full text3D electron diffraction applied to complex nanoparticles and nanominerals
Enrico Mugnaioli (1), Mauro Gemmi (2)
(1) Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy. (2) Center for Materials Interfaces, Electron Crystallography, Istituto Italiano di Tecnologia, Pontedera (PI), Italy.
Electron diffraction has been long regarded as a purely quantitative method, due to poor accuracy and dynamical effects. Yet, in the late 2000’s the first attempts to collect single-crystal electron diffraction data and to use them for ab-initio structure determination revealed unexpectedly successful [1]. In the following ten years, the method has attracted the attention of mineralists, chemists, material scientists and structural biologists, because it has proved able to cover the missing gap between the smallest crystals tractable with X-rays (1-50 μm) and the smallest crystalline seeds (10-100 nm) [2].
The so-called 3D electron diffraction method is very efficient with organic compounds and macromolecules despite their beam sensitivity, but is especially powerful for inorganic materials. In fact, it is possible to collect reliable structural data from particles and areas as small as few tens of nanometers. Here we will show the recent characterization of a series of sub-micrometric crystalline phases found in corundum grains from Luobusa ophiolite, Tibet, China [3-4] (Figure 1). A rich collection of unexpected new minerals was discovered inside a handful of FIB lamellae. Moreover, we will display that 3D electron diffraction can be used for the structural characterization of complex synthetic nanoparticle systems [5-6], possibly besting more established crystallographic methods like powder X-ray diffraction and high-resolution (S)TEM imaging
True molecular conformation and structure determination of remarkable polycyclic aromatic hydrocarbons
No full textBack to Table of contents
ECM33 BOOK OF ABSTRACTS
279
MS39 Crystallography at the nanoscale
MS39-03
True molecular conformation and structure determination of remarkable polycyclic aromatic hydrocarbons
I. Andrusenko 1, E. Mugnaioli 2, M. Gemmi 1, W. Schmidt 3
1Istituto Italiano di Tecnologia, Center for Materials Interfaces, Electron Crystallography - Pontedera (Italy),
2Università di Pisa, Dipartimento di Scienze della Terra - Pisa (Italy), 3PAH Research - Igling-Holzhausen
(Germany)
Abstract
The true molecular conformation and the crystal structure of four large (30 – 46 C atoms) polycyclic aromatic
hydrocarbons (PAHs)1,2 were determined by direct methods from 3D electron diffraction (3D ED)3 data, a result
that could not be achieved by single crystal X-ray diffraction (XRD) due to limited crystal size and the thin leaflet
morphology of the samples. Additionally, three of such compounds were isolated as by-products in the synthesis
of similar materials and, therefore, were available only in very limited amount.
The main strength of 3D ED is the ability to perform single crystal diffraction on sub-micrometric areas. Therefore,
this technique can be used for structure determination when crystal size is the limiting factor for single crystal
XRD. Remarkably, this analytical protocol can be performed even on extremely small sample batches, which
cannot be conveniently prepared for conventional powder XRD.
Moreover, the molecular conformation of two compounds could not be determined via classical spectroscopic
methods due to the large size of the molecules and the occurrence of multiple and reciprocally connected
aromatic rings. On the other hand, 3D ED data provided not only ab-initio structure solution, but also the
unbiased determination of the internal molecular conformation. It is noteworthy that ab-initio crystal structure
determination does not require information about the molecular conformation, but only a rough estimation of the
atomic content of the unit cell.
The other two compounds were synthesised more than 50 years ago, but have hitherto remained structurally
unsolved. All molecules have a considerable interest due to their optoelectronic properties, which led to the
creation of a number of functionalised materials based on PAH backbones. Detailed synthetic routes,
spectroscopic analyses and promising properties are also discussed.
References
1. Hall, C. L., Andrusenko, I., Potticary, J., Gao, S., Liu, X., Schmidt, W., Marom, N., Mugnaioli, E., Gemmi, M.
& Hall, S. R. (2021) 3D Electron Diffraction Structure Determination of Terrylene, a Promising Candidate for
Intermolecular Singlet Fission. ChemPhysChem 22(15), 1631-1637.
2. Andrusenko, I., Hall, C. L., Mugnaioli, E., Potticary, J., Schmidt, W., Gao, S., Marom, N., Hall, S. R. & Gemmi,
M. (2022) True Molecular Conformation and Structure Determination by 3D Electron Diffraction of PAH By-
Products Potentially Useful for Electronic Applications, in preparation.
3. Gemmi, M., Mugnaioli, E., Gorelik, T. E., Kolb, U., Palatinus, L., Boullay, P., Hovmöller, S. & Abrahams, J. P.
(2019) 3D Electron Diffraction: The Nanoctystallography Revolution. ACS Cent. Sci. 5, 1315-1329
Structural Characterization of Organics Using Manual and Automated Electron Diffraction
No full textIn the last decade the importance of transmission electron microscopic studies has become increasingly important with respect to the characterization of organic materials, ranging from small organic molecules to polymers and biological macromolecules. This review will focus on the use of transmission electron microscope to perform electron crystallography experiments, detailing the approaches in acquiring electron crystallographic data. The traditional selected area approach and the recently developed method of automated diffraction tomography (ADT) will be discussed with special attention paid to the handling of electron beam sensitive organic materials. RI Kolb, Ute/A-2642-2011; Mugnaioli, Enrico/E-6237-201
Investigation of bio-related minerals by electron-diffraction tomography: Vaterite, dental hydroxyapatite, and crystalline nanorods in sponge primmorphs
No full textAutomated electron diffraction tomography - a new tool for nano crystal structure analysis
No full textAutomated electron Diffraction Tomography (ADT) comprises an upcoming method for "ab intio" structure analysis of nano crystals. ADT allows fine sampling of the reciprocal space by sequential collection of electron diffraction patterns while tilting a nano crystal in fixed tilt steps around an arbitrary axis. Electron diffraction is collected in nano diffraction mode (NED) with a semi-parallel beam with a diameter down to 50 nm. For crystal tracking micro-probe STEM imaging is used. Full automation of the acquisition procedure allowed optimisation of the electron dose distribution and therefore analysis of highly beam sensitive samples. Cell parameters, space group and reflection intensities can be determined directly within a reconstructed 3d diffraction volume using a dedicated software package (ADT3D). Intensity data sets extracted from such a volume usually show a high coverage and significantly reduced dynamical effects due to "off-zone" acquisition. The use of this data for "ab initio" structure solution by direct methods implemented in standard programs for X-ray crystallography is demonstrated. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim RI Mugnaioli, Enrico/E-6237-2011; Kolb, Ute/A-2642-201
Crystalline Nanorods as Possible Templates for the Synthesis of Amorphous Biosilica during Spicule Formation in Demospongiae
No full textHigh-resolution microscopy shows that during the initial stages of demosponge spicule formation, a primordial crystalline structure is formed within the axial filament. The recently developed electron diffraction tomography technique reveals that the nanorods have a layered structure that matches smectitic phyllosilicates. These intracellular nanorods have been considered as precursors of mature spicules. RI Kolb, Ute/A-2642-2011; Natalio, Filipe/D-4417-2011; Mugnaioli, Enrico/E-6237-201
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