Felizitas Kirner

European Synchrotron Radiation Facility

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Elena V. Sturm

Ludwig-Maximilians-Universität München

Axel Lubk

TU Dresden

Sebastian Sturm

Ludwig-Maximilians-Universität München

Dmitry Lapkin

Deutsches Elektronen-Synchrotron DESY

Ivan A. Vartanyants

Deutsches Elektronen-Synchrotron DESY

Igor A. Baburin

Ludwig-Maximilians-Universität München

Alexandr Ignatenko

Deutsches Elektronen-Synchrotron DESY

Thomas Gemming

Leibniz Institute for Solid State and Materials Research

Knut Müller‐Caspary

Ludwig-Maximilians-Universität München

Helmut Cölfen

University of Konstanz

Cooperative Institutions

University of Konstanz

Deutsches Elektronen-Synchrotron DESY

TU Dresden

Leibniz Institute for Solid State and Materials Research

Max Planck Society

RWTH Aachen University

European Synchrotron Radiation Facility

Petersburg Nuclear Physics Institute

Russian Academy of Sciences

Institute for Solid State Physics and Optics

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Morphogenesis of Magnetite Mesocrystals: Interplay between Nanoparticle Morphology and Solvation Shell

Chemistry of Materials (2021)

Julian Brunner Britta Maier Sabrina L. J. Thomä Felizitas Kirner Igor A. Baburin

Nanoparticle assemblies with long-range packing order and preferred crystallographic orientation of building blocks, i.e., mesocrystals, are of high interest not only because of their unique physical properties but also due to their complex structure and morphogenesis. In this study, faceted mesocrystals have been assembled from the dispersion of truncated cubic-shaped iron oxide nanoparticles stabilized by oleic acid (OA) molecules using the nonsolvent "gas phase diffusion technique" into an organic solvent. The effects of synthesis conditions as well as of the nanoparticle size and shape on the structure and morphogenesis of mesocrystals were examined. The interactions of OA-capped iron oxide nanoparticles with solvent molecules were probed by analytical ultracentrifugation and double difference pair distribution function analysis. It was shown that the structure of the organic shell significantly depends on the nature and polarity of solvent molecules. For the nonpolar solvents, the interaction of the aliphatic chains of OA molecules with the solvent molecules is favorable and the chains extend into the solvent. The solvation shell around the nanoparticles is more extended in nonpolar and more compact in polar solvents. There is a clear trend for more spherical particles to be assembled into the fcc superlattice, whereas less truncated cubes form rhombohedral and tetragonal structures. The observed changes in packing symmetry are reminiscent of structural polymorphism known for "classical" (atomic and molecular) crystals.

Tetragonal crystal system

Solvation shell

10.1021/acs.chemmater.1c01941

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Exploring the Crystalline Structure of Gold Mesocrystals Using X-ray Diffraction

Crystals (2023)

Aleksandra Chumakova Felizitas Kirner Andrei Chumakov Stephan V. Roth Alexeï Bosak

Mesocrystals are a class of nanostructured material where individual nanocrystals are arranged in a distinct crystallographic orientation. The multiple-length-scale order in such materials plays an essential role in the emergent physical and chemical phenomena. Our work studies the structure of a faceted mesocrystal composed of polystyrene-functionalized single crystalline gold nanoparticles using complementary ultrasmall- and wide-angle X-ray scattering (USAXS and WAXS) with electron microscopy. The results of the data analysis shed some light on the details of the microscopic structure of mesocrystals and their structuration principle.

Small-angle X-ray scattering

Polystyrene

10.3390/cryst13081204

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Tomographic reconstruction of power density in electron beams used for machining

Proceedings of the IEEE (1983)

Felizitas Kirner

This letter describes a new method to measure the spatial distribution of the power density in electron beams. At various angles, the projections of the current density are taken by scanning the beam with a straight edge. The spatial distribution is reconstructed by using the "Convoluted Backprojection." The resolution obtained is about 3 percent.

Tomographic reconstruction

Power density

10.1109/proc.1983.12672

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Tailoring Plasmonics of Au@Ag Nanoparticles by Silica Encapsulation

arXiv (Cornell University) (2021)

Johannes Schultz Felizitas Kirner Pavel Potapov B. Büchner Axel Lubk

Hybrid metallic nanoparticles encapsulated in oxide shells are currently intensely studied for plasmonic applications in sensing, medicine, catalysis, and photovoltaics. Here, we introduce a method for the synthesis of Au@Ag@SiO$_2$ cubes with a uniform silica shell of variable and adjustable thickness in the nanometer range; and we demonstrate their excellent, highly reproducible, and tunable optical response. Varying the silica shell thickness, we could tune the excitation energies of the single nanoparticle plasmon modes in a broad spectral range between 2.55 and 3.25 eV. Most importantly, we reveal a strong coherent coupling of the surface plasmons at the silver-silica interface with the whispering gallery resonance at the silica-vacuum interface leading to a significant field enhancement at the encapsulated nanoparticle surface in the range of 100 % at shell thicknesses $t\,$$\simeq\,$20 nm. Consequently, the synthesis method and the field enhancement open pathways to a widespread use of silver nanoparticles in plasmonic applications including photonic crystals and may be transferred to other non-precious metals.

Plasmonic Nanoparticles

Nanometre

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Modular Toolkit of Multifunctional Block Copoly(2‐oxazoline)s for the Synthesis of Nanoparticles

Chemistry - A European Journal (2021)

Philipp Keckeis Enriko Zeller Carina M. Jung Patricia Besirske Felizitas Kirner

Abstract Post‐polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor‐made materials with superior properties. This concept was adapted to well‐defined block copolymers of the poly(2‐oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water‐soluble, alkyne‐ and alkene‐containing segments were synthesized and orthogonally modified with various low‐molecular weight functional molecules by copper(I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) and thiol‐ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.

Alkyne

Oxazoline

Alkene

10.1002/chem.202101327

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A Symmetry‐Based Kinematic Theory for Nanocrystal Morphology Design

Angewandte Chemie International Edition (2022)

Bing Ni Guillermo González‐Rubio Felizitas Kirner Siyuan Zhang Helmut Cölfen

The growth of crystalline nanoparticles (NPs) generally involves three processes: nucleation, growth, and shape evolution. Among them, the shape evolution is less understood, despite the importance of morphology for NP properties. Here, we propose a symmetry-based kinematic theory (SBKT) based on classical growth theories to illustrate the process. Based on the crystal lattice, nucleus (or seed) symmetry, and the preferential growth directions under the experimental conditions, the SBKT can illustrate the growth trajectories. The theory accommodates the conventional criteria of the major existing theories for crystal growth and provides tools to better understand the symmetry-breaking process during the growth of anisotropic structures. Furthermore, complex dendritic growth is theoretically and experimentally demonstrated. Thus, it provides a framework to explain the shape evolution, and extends the morphogenesis prediction to cases, which cannot be treated by other theories.

Lattice (music)

Growth theory

Morphology

10.1002/anie.202200753

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Revealing the impact of polystyrene-functionalization of Au octahedral nanocrystals of different sizes on formation and structure of mesocrystals

arXiv (Cornell University) (2023)

Dmitry Lapkin Shweta Singh Felizitas Kirner Sebastian Sturm Dameli Assalauova

The self-assembly of anisotropic nanocrystals (stabilized by organic capping molecules) with pre-selected composition, size, and shape allows for the creation of nanostructured materials with unique structures and features. For such a material, the shape and packing of the individual nanoparticles play an important role. This work presents a synthesis procedure for {\omega}-thiol-terminated polystyrene (PS-SH) functionalized gold nanooctahedra of variable size (edge length 37, 46, 58, and 72 nm). The impact of polymer chain length (Mw: 11k, 22k, 43k, and 66k g/mol) on the growth of colloidal crystals (e.g. mesocrystals) and their resulting crystal structure is investigated. Small-angle X-ray scattering (SAXS) and scanning transmission electron microscopy (STEM) methods provide a detailed structural examination of the self-assembled faceted mesocrystals based on octahedral gold nanoparticles of different size and surface functionalization. Three-dimensional angular X-ray cross-correlation analysis (AXCCA) enables high-precision determination of the superlattice structure and relative orientation of nanoparticles in mesocrystals. This approach allows us to perform non-destructive characterization of mesocrystalline materials and reveals their structure with resolution down to the nanometer scale.

Small-angle X-ray scattering

Polystyrene

Surface Modification

10.48550/arxiv.2306.14507

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Multiscale Reciprocal Space Mapping of Magnetite Mesocrystals (Adv. Mater. 2/2023)

Advanced Materials (2023)

Aleksandra Chumakova Tristan Steegemans Igor A. Baburin А. А. Мистонов Ilya S. Dubitskiy

Magnetite Mesocrystals Mesocrystals are a class of nanostructured materials where a multiple-length-scale structure is a prerequisite of many interesting phenomena. In article number 2207130, Aleksandra Chumakova, Elena V. Sturm, Alexeï Bosak, and co-workers describe the detailed analysis of X-ray diffraction from magnetite mesocrystals with different particle sizes and shapes, in tandem with electron microscopy. The revealed features provide valuable input to the models of mesocrystal growth.

Magnetite Nanoparticles

10.1002/adma.202370011

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Structural Study of a Self-Assembled Gold Mesocrystal Grain by Coherent X-ray Diffraction Imaging

arXiv (Cornell University) (2021)

Jérôme Carnis Felizitas Kirner Dmitry Lapkin Sebastian Sturm Y. Y. Kim

Mesocrystals are nanostructured materials consisting of individual nanocrystals having a preferred crystallographic orientation. On mesoscopic length scales, the properties of mesocrystals are strongly affected by structural heterogeneity. Here, we report the detailed structural characterization of a faceted mesocrystal grain self-assembled from 60 nm sized gold nanocubes. Using coherent X-ray diffraction imaging, we determined the structure of the mesocrystal with the resolution sufficient to resolve each gold nanoparticle. The reconstructed electron density of the gold mesocrystal reveals its intrinsic structural heterogeneity, including local deviations of lattice parameters, and the presence of internal defects. The strain distribution shows that the average superlattice obtained by angular X-ray cross-correlation analysis and the real, multidomain structure of a mesocrystal are very close to each other, with a deviation less than 10 percent. These results will provide an important impact to understanding of the fundamental principles of structuring and self-assembly including ensuing properties of mesocrystals.

Mesoscopic physics

Selected area diffraction

Coherent diffraction imaging

10.48550/arxiv.2103.01822

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Correction: Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging

Nanoscale (2021)

Jérôme Carnis Felizitas Kirner Dmitry Lapkin Sebastian Sturm Young Yong Kim

Correction for ‘Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging’ by Jerome Carnis et al., Nanoscale, 2021, DOI: 10.1039/D1NR01806J.

Coherent diffraction imaging

Gold standard (test)

10.1039/d1nr90126e

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Citations (1)