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Item type:Publication, Access status: with files , Multimodal synchrotron X-ray analysis of palm-leaf manuscripts: structural and compositional signatures of botanical genus, manufacture, and provenance(Springer, 2026-10-06); ; ; ; Palm-leaf manuscripts are cultural artifacts from South and Southeast Asia, yet diverse preparation methods and degradation histories complicate material characterization and comparison. We use a multimodal synchrotron approach combining small- and wide-angle X-ray scattering with X-ray fluorescence to extract structural and compositional descriptors from unprocessed leaves, writing supports, and manuscripts. Supervised learning evaluates differences related to genus, processing stage, and geographical origin. The processing stage is classified reliably, whereas genus separation is clearer in processed materials than in unprocessed leaves. Origin classification shows partial separability, with distinct regional profiles and overlaps reflecting shared preparation traditions, class imbalance, and botanical and degradation-related factors. Classification relies on multivariate combinations of crystallinity, fibril orientation, and elemental descriptors. This scalable, non-destructive framework supports comparison of collections and investigation of material similarities among traditions. The classifications represent comparative material profiles rather than definitive provenance assignments and must be combined with codicological and historical evidence.Publicationtype: Journal Article22 5 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Transition-metal azo Schiff base complexes: nonlinear optics across solutions, thin films and nanocomposites(Wiley, 2025-10-24); ; ; ; This paper investigates the nonlinear optical (NLO) properties of azo-based Schiff base ligand and its corresponding complexes incorporating Cu(II) and Zn(II) metal cations, designed upon the previous synthesis work. Both 2nd and 3rd order NLO properties are examined, with a particular focus on their potential for optoelectronic and photonic applications. The Z-scan technique is employed to analyze NLO refraction and NLO absorption in solution. All samples exhibit positive NLO phenomena, with Zn(L)2 showing the highest values (𝝌(3) = 27.95 × 10−22 m2 V−2, 𝜸 = 54.44 × 10−47 m5 V−2), attributed to enhanced ligand-to-metal charge transfer (LMCT). Additionally, thin films deposited via the spin coating method undergo 3rd order NLO analysis through the Maker fringe technique. THG analysis further confirms superior 3rd order NLO performance in Zn(L)2, exceeding several benchmark transition-metal complexes. 2nd order NLO properties are also explored in hybrid nanocomposites designed from Zn(L)2 embedded in nanoporous pSiO2 membrane. This structure exhibits anisotropic SHG behavior, with 𝝌 (2) = 0.11 pm V−1 under s-p polarization, suggesting polarization confinement within nanochannels. The results clearly demonstrate that transition-metal azo Schiff base complexes, particularly Zn(L)2, exhibit strong NLO responses, positioning them as potential candidates for applications in all-optical switching and frequency conversion.Publicationtype: Journal Article22 18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Colossal effect of nanopore surface ionic charge on the dynamics of confined water(American Chemical Society (ACS), 2025-09-29); ; 31 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Self-assembly of bent-core nematics in nanopores(American Chemical Society (ACS), 2025-06-17); ; ; ; Bent-core nematic liquid crystals exhibit unique properties, including giant flexoelectricity and polar electro-optic responses, making them ideal for energy conversion and electro-optic applications. When confined in nanopores, they can stabilize chiral nanostructures, enhance polar order, and enable defect-driven switching -- offering potential in nanofluidics, sensing, and adaptive optics. Here we examine the thermotropic ordering of the bent-core dimer CB7CB confined in anodic aluminum oxide (AAO) and silica membranes with precisely engineered cylindrical nanochannels -- ranging from just a few nanometers to several hundred nanometers. These well-aligned nanochannels enable high-resolution polarimetry studies of optical anisotropy, revealing how geometric confinement affects molecular organization and phase behavior. Under weak confinement, CB7CB forms a layered heterophase structure, with nematic, splay-bent, and twist-bent heliconical phases likely arranged concentrically. As confinement increases, a Landau-de Gennes analysis shows that ordered phases are suppressed, leaving only a paranematic phase under strong spatial constraints. Remarkably, temperature-dependent changes in optical birefringence under confinement closely resemble those seen under applied electric fields, revealing a parallel between geometric and electro-optic effects. Overall, our work demonstrates how nanoconfinement allows one to systematically tailor the self-assembly and optical behavior of bent-core nematics, enabling novel functionalities in responsive and anisotropic materials.Publicationtype: Preprint18 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Self-assembly of bent-core nematics in nanopores(Wiley, 2025); ; ; Bent-core nematic liquid crystals exhibit unique properties, including giant flexoelectricity and polar electro-optic responses, making them ideal for energy conversion and electro-optic applications. When confined in nanopores, they can stabilize chiral nanostructures, enhance polar order, and enable defect-driven switching – offering potential in nanofluidics, sensing, and adaptive optics. The thermotropic ordering of the bent-core dimer CB7CB confined in anodic aluminum oxide (AAO) and silica membranes with precisely engineered cylindrical nanochannels – ranging from just a few nanometers to several hundred nanometers–is examined. These well-aligned nanochannels enable high-resolution polarimetry studies of optical anisotropy, revealing how geometric confinement affects molecular organization and phase behavior. Under weak confinement, CB7CB forms a layered heterophase structure, with nematic, splay-bent, and twist-bent heliconical phases likely arranged concentrically. As confinement increases, a Landau-de Gennes analysis shows that ordered phases are suppressed, leaving only a paranematic phase under strong spatial constraints. Remarkably, temperature-dependent changes in optical birefringence under confinement closely resemble those seen under applied electric fields, revealing a parallel between geometric and electro-optic effects. Overall, this work demonstrates how nanoconfinement allows one to systematically tailor the self-assembly and optical behavior of bent-core nematics, enabling novel functionalities in responsive and anisotropic materials.Publicationtype: Journal Article25 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Wafer-scale fabrication of mesoporous silicon functionalized with electrically conductive polymers(Elsevier, 2024-08-01); ; ; The fabrication of hybrid materials consisting of nanoporous hosts with conductive polymers is a challenging task, since the extreme spatial confinement often conflicts with the stringent physico-chemical requirements for polymerization of organic constituents. Here, several low-threshold and scalable synthesis routes for such hybrids are presented. First, the electrochemical synthesis of composites based on mesoporous silicon (pSi) and the polymers PANI, PPy and PEDOT is discussed and validated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Polymer filling degrees of ≥74 % are achieved. Second, the production of PEDOT/pSi hybrids, based on the solid-state polymerization (SSP) of DBEDOT to PEDOT is shown. The resulting amorphous structure of the nanopore-embedded PEDOT is investigated via in-situ synchrotron-based X-ray scattering. In addition, a twofold increase in the electrical conductivity of the hybrid compared to the porous silicon host is shown, making this system particularly promising for thermoelectric applications.Publicationtype: Journal Article15 55 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Self-assembly of ionic superdiscs in nanopores(American Chemical Society (ACS), 2024-06-04); ; ; ; Discotic ionic liquid crystals (DILCs) consist of self-assembled superdiscs of cations and anions that spontaneously stack in linear columns with high one-dimensional ionic and electronic charge mobility, making them prominent model systems for functional soft matter. Compared to classical nonionic discotic liquid crystals, many liquid crystalline structures with a combination of electronic and ionic conductivity have been reported, which are of interest for separation membranes, artificial ion/proton conducting membranes, and optoelectronics. Unfortunately, a homogeneous alignment of the DILCs on the macroscale is often not achievable, which significantly limits the applicability of DILCs. Infiltration into nanoporous solid scaffolds can, in principle, overcome this drawback. However, due to the experimental challenges to scrutinize liquid crystalline order in extreme spatial confinement, little is known about the structures of DILCs in nanopores. Here, we present temperature-dependent high-resolution optical birefringence measurement and 3D reciprocal space mapping based on synchrotron X-ray scattering to investigate the thermotropic phase behavior of dopamine-based ionic liquid crystals confined in cylindrical channels of 180 nm diameter in macroscopic anodic aluminum oxide membranes. As a function of the membranes’ hydrophilicity and thus the molecular anchoring to the pore walls (edge-on or face-on) and the variation of the hydrophilic-hydrophobic balance between the aromatic cores and the alkyl side chain motifs of the superdiscs by tailored chemical synthesis, we find a particularly rich phase behavior, which is not present in the bulk state. It is governed by a complex interplay of liquid crystalline elastic energies (bending and splay deformations), polar interactions, and pure geometric confinement and includes textural transitions between radial and axial alignment of the columns with respect to the long nanochannel axis. Furthermore, confinement-induced continuous order formation is observed in contrast to discontinuous first-order phase transitions, which can be quantitatively described by Landau-de Gennes free energy models for liquid crystalline order transitions in confinement. Our observations suggest that the infiltration of DILCs into nanoporous solids allows tailoring their nanoscale texture and ion channel formation and thus their electrical and optical functionalities over an even wider range than in the bulk state in a homogeneous manner on the centimeter scale as controlled by the monolithic nanoporous scaffolds.Publicationtype: Journal Article17 18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Impact of confinement and polarizability on dynamics of ionic liquids(American Institute of Physics (AIP), 2022-02-08); ; ; ; Polarizability is a key factor when it comes to an accurate description of different ionic systems. The general importance of including polarizability into molecular dynamics simulations was shown in various recent studies for a wide range of materials, ranging from proteins to water to complex ionic liquids and for solid-liquid interfaces. While most previous studies focused on bulk properties or static structure factors, this study investigates in more detail the importance of polarizable surfaces on the dynamics of a confined ionic liquid in graphitic slit pores, as evident in modern electrochemical capacitors or in catalytic processes. A recently developed polarizable force field using Drude oscillators is modified in order to describe a particular room temperature ionic liquid accurately and in agreement with recently published experimental results. Using the modified parameters, various confinements are investigated and differences between non-polarizable and polarizable surfaces are discussed. Upon introduction of surface polarizability, changes in the dipole orientation and in the density distribution of the anions and cations at the interface are observed and are also accompanied with a dramatic increase in the molecular diffusivity in the contact layer. Our results thus clearly underline the importance of considering not only the polarizability of the ionic liquid but also that of the surface.Publicationtype: Journal ArticleScopus© Citations 9 105 367 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dynamics of Water Confined in Mesopores with Variable Surface Interaction(2021-03-07); ; ; ; We have investigated the dynamics of liquid water confined in mesostructured porous silica (MCM-41) and periodic mesoporous organosilicas (PMOs) by incoherent quasielastic neutron scattering experiments. The effect of tuning the water/surface interaction from hydrophilic to more hydrophobic on the water mobility, while keeping the pore size in the range 3.5-4.1 nm, was assessed from the comparative study of three PMOs comprising different organic bridging units and the purely siliceous MCM-41 case. An extended dynamical range was achieved by combining time-of-flight (IN5B) and backscattering (IN16B) quasielastic neutron spectrometers providing complementary energy resolutions. Liquid water was studied at regularly spaced temperatures ranging from 300 K to 243 K. In all systems, the molecular dynamics could be described consistently by the combination of two independent motions resulting from fast local motion around the average molecule position and the confined translational jump diffusion of its center of mass. All the molecules performed local relaxations, whereas the translational motion of a fraction of molecules was frozen on the experimental timescale. This study provides a comprehensive microscopic view on the dynamics of liquid water confined in mesopores, with distinct surface chemistries, in terms of non-mobile/mobile fraction, self-diffusion coefficient, residence time, confining radius, local relaxation time, and their temperature dependence. Importantly, it demonstrates that the strength of the water/surface interaction determines the long-time tail of the dynamics, which we attributed to the translational diffusion of interfacial molecules, while the water dynamics in the pore center is barely affected by the interface hydrophilicity.Publicationtype: Journal Article68 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adaptive photonic metamaterials by self-assembly of liquid crystals in nanoporous solidsSelf-organized multiscale porosity in terms of precise pore size, shape, and orientation has been achieved in many base materials. Here we exemplify that in combination with self-assembly of liquid crystals in pore space this provides particularly versatile pathways for the engineering of photonic metamaterials. We present temperature-dependent structuralcharacterizations of the thermodynamic and structural self-assembly behavior of the liquid crystals confined in nanoporous silicon, silica and alumina in combination with experiments on the resulting effective optics of the hybrid materials.Publicationtype: Conference Paper28