Resonant X-ray Diffraction Research Articles

Synthesis, characterization, In-silico and In-vitro investigation of sulfonamide based esters

In this study three new esters; methyl 4-((4-methoxyphenylsulfonamido)methyl)cyclohexane carboxylate; C16H23NO5S (I), ethyl 4-((4-methoxyphenylsulfonamido)methyl)cyclohexane carboxylate; C17H25NO5S (II) and isopropyl 4-((4-methoxyphenylsulfonamido)methyl)-cyclohexane carboxylate; C18H27NO5S (III) were synthesized in crystalline (I and II) and amorphous (III) form. Structural confirmation of these synthesized compounds was done using fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), Mass and single crystal X-ray diffraction. The synthesized compounds were further subjected to their computational studies. All the synthesized compounds were screened for their in-vitro biological applications in term of antimicrobial, enzyme inhibition and free radical scavenging studies using spectrophotometric protocols. It was depicted from result that III gave higher antibacterial as well as antifungal activity comparable to the standard drugs. While, ester I showed profound antiradical scavenging activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) radical. The compounds were also screened against esterase family; Acetylcholine esterase (AChE) and Butyrylcholine esterase (BChE) and it was found that I gave excellent inhibition activity towards AChE (91.1±0.7 %) as well as against BChE (84.1±0.9 %). In order to check the interactions of the compounds towards active sites of the respective enzyme, docking studies were carried out which confirmed that such compounds have good interaction to the amino acids residues on the active sites.

Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through in Situ Resonant X-ray Diffraction Combined with ab Initio Modeling

Charge Reorganization at the Adsorbate Covered Electrode Surface Probed through <i>in Situ</i> Resonant X-ray Diffraction Combined with <i>ab Initio</i> Modeling

Development of holmium doped eutectic Sn-Ag lead-free solder for electronic packaging

PurposeThis study aims to summarize the effects of minor addition of Ho REE on the structure, mechanical strength and thermal stability of binary Sn- Ag solder alloys for high-performance applications.Design/methodology/approachThis study investigates the effect of a small amount of holmium addition on the microstructure, thermal stability, mechanical behaviour and wettability of environmentally friendly eutectic melt-spun process Sn – Ag solder alloys. Dynamic resonance technique, X-ray diffraction (XRD) and scanning electron microscopy were carried to study stiffness, identification of the phases and the morphology features of the solder. Structure and microstructure analysis indicated that presence of rhombohedral ß-Sn phase in addition to orthorhombic IMC Ag3Sn phase dispersed in Sn-matrix. Also, the results showed that Ho rare earth addition at a small trace amount into Sn-Ag system reduces and improves the particle size of both rhombohedral ß-Sn and orthorhombic IMC Ag3Sn based on the adsorption effect of the active RE element. The adsorption of Ho at grain boundaries resulted in Ag3Sn more uniform needle-like which is distributed in the ß-Sn matrix. The fine and uniform microstructure leads to improvement of mechanical strength. The microstructure refinement is due to the high surface free energy of IMC Ag3Sn grains, and it prevents the dislocation slipping. This maybe enhance the micro-hardness and micro-creep hence delays the breaking point of the solder. Ho (RE) trace addition could enhance the melting temperature and contact angle up to 215°C and 31°, Respectively, compared with plain solder. All results showed that Ho trace addition element has an effective method to enhance new solder joints.FindingsEffect of rare earth element Ho particles on the microstructure and mechanical behavior of eutectic Sn-3.5Ag solder alloy was studied. Some important conclusions are summarized in the following: microstructure investigations revealed that the addition of Ho particles to eutectic Sn-3.5Ag inhibited in reducing and refines the crystallite size as well as the Ag3Sn IMC which reinforced the strength of plain solder alloy. The mechanical properties values such as Young’s modulus, Vickers microhardness of Sn-3.5Ag solder alloy can be significantly improved by adding a trace amount of Ho particles compared with plain solder due to the existence of finer and higher volume fraction of Ag3SnIMC. These variations can be understood by considering the plastic deformation. The strengthening mechanism of the Sn-3.5Ag-Ho solder alloy could be explained in terms of Ho harden particles and finer IMC, which are distributed within eutectic regions because they act as pinning centres which inhibited the mobility of dislocation that concentrated around the grain boundaries. The results show that the best creep resistance is obtained when the addition of Ho 0.5 is compared to plain solder. The addition of Ho on Sn-3.5Ag lead-free solder alloy decreases the melting temperature to few degrees.Originality/valueDevelopment of holmium-doped eutectic Sn-Ag lead-free solder for electronic packaging.

Unraveling the Charge Distribution at the Metal-Electrolyte Interface Coupling in Situ Surface Resonant X-Ray Diffraction with Ab Initio Calculations

The comprehension of the mechanisms underlying the charge distribution at the electrochemical interface is a fundamental step in sight of the performance of catalytic materials. Several techniques allow the atomic structure of the metal surface to be characterized, while no experimental method enables to obtain the charge distribution at the catalyst surface and in the electrolyte in the interfacial region. Combining experimental and ab initio calculations, we succeeded in quantitatively describing the charge distribution at the electrochemical interface of the archetypal system Pt(111) in an acidic medium. In our approach, we couple in situ surface resonant X-ray diffraction, a site-sensitive experimental technique probing both the atomic and the electronic surface structures, with ab initio calculations, recently implemented to describe the Helmholtz double layer formed at the metal-solution interface. In the potential region in between the hydrogen desorption and the (bi)sulfate adsorption, we could determine the charge distribution on each of the metal surface layers and the distance separating the metal from the oppositely charged disordered ionic plane. We could reveal the presence of an electric dipole over the two outermost platinum layers. Our results demonstrate the potential of this original approach to unveil the electronic densities at the electrochemical interfaces, a challenging topic for the understanding of electrochemical reactivity.

Competition between helimagnetic and ferroquadrupolar ordering in a monoaxial chiral magnetDyNi3Ga9studied by resonant x-ray diffraction

Successive phase transitions in a rare-earth monoaxial chiral magnet ${\mathrm{DyNi}}_{3}{\mathrm{Ga}}_{9}$ have been investigated by resonant x-ray diffraction. Magnetic dipole and electric quadrupole degrees of freedom arising from the large angular moment of $J=15/2$, in combination with the symmetric and antisymmetric exchange interactions and the crystal field anisotropy, give rise to competing ordered phases. We show that the antiferromagnetically coupled Dy moments in the $ab$ plane form an incommensurate helimagnetic order with $\mathbit{q}\ensuremath{\sim}(0,0,0.43)$ just below ${T}_{\text{N}}=10$ K, which further exhibits successive first-order transitions to the commensurate helimagnetic order with $\mathbit{q}=(0,0,0.5)$ at ${T}_{\text{N}}^{\ensuremath{'}}=9.0$ K, and to the canted antiferromagnetic order with $\mathbit{q}=(0,0,0)$ at ${T}_{\text{N}}^{\ensuremath{''}}=8.5$ K, both with large coexistence regions. The relation of the magnetic helicity and the crystal chirality in ${\mathrm{DyNi}}_{3}{\mathrm{Ga}}_{9}$ is also uniquely determined. Splitting of the (6,0,0) Bragg peak is observed below ${T}_{\text{N}}^{\ensuremath{''}}$, reflecting the lattice distortion due to the ferroquadrupole order. In the canted antiferromagnetic phase, a spin-flop transition takes place at 5 K when the temperature is swept in a weak magnetic field. We discuss these transitions from the viewpoint of the competing energies described above.

Resolving the backbone tilt of crystalline poly(3-hexylthiophene) with resonant tender X-ray diffraction.

The way in which conjugated polymers pack in the solid state strongly affects the performance of polymer-based optoelectronic devices. However, even for the most crystalline conjugated polymers the precise packing of chains within the unit cell is not well established. Here we show that by performing resonant X-ray diffraction experiments at the sulfur K-edge we are able to resolve the tilting of the planar backbones of crystalline poly(3-hexylthiophene) (P3HT) within the unit cell. This approach exploits the anisotropic nature of the X-ray optical properties of conjugated polymers, enabling us to discern between different proposed crystal structures. By comparing our data with simulations based on different orientations, a tilting of the planar conjugated backbone with respect to the side chain stacking direction of 30 ± 5° is determined.

A New Phenolic Diterpene From the Leaves ofRosmarinus officinalis

As part of our continuous studies on dietary supplements for diabetes, 1 new phenolic diterpene, 7-butoxyrosmanol (1), and 3 known ones (2-4) were isolated from Rosmarinus officinalis. The new structure was elucidated based on comprehensive spectroscopic methods, including multiple nuclear magnetic resonance techniques, mass spectrometry, and x-ray diffraction analysis. In addition, compound 1 showed moderate activity against pancreatic lipase with an IC50value of 46.2 μM.

Development of Pulse-by-pulse Helicity Switching of a Circularly Polarized XFEL Beam and its Application to Time-resolved Resonant X-ray Diffraction Experiment

Development of Pulse-by-pulse Helicity Switching of a Circularly Polarized XFEL Beam and its Application to Time-resolved Resonant X-ray Diffraction Experiment

Tuning iron-amine electronic coupling by different aromatic bridges based on ferrocene-ethynyl-triarylamine systems

The syntheses of a series of ferrocene (Fc)–ethynyl–triarylamine (TAA) inorganic–organic mixed-valence systems with different aromatic bridge linkers (Aryl = 1,4-phenyl [1], 1,4-naphthyl [2], 9,10-anthryl [3]) are reported in this study. These systems were accessible with good yields through the classical Sonogashira cross-coupling reactions of brominated intermediates, 1a, 2a, and 3a, with ethynylferrocene, respectively. Target compounds 1–3 were fully characterized by nuclear magnetic resonance, elemental analysis, and single-crystal X-ray diffraction analysis. Redox and electronic coupling properties were investigated by anodic voltammetry, UV–visible–near-infrared (NIR) spectroelectrochemistry, and density functional theory (DFT) calculations. Experimental results revealed that the first anodic steps of compounds 1–3 occur in ethynylferrocene units and the second redox process comes from triphenylamine moieties. This result is in accordance with the spin density distribution results. The Fe–N electronic coupling of singly oxidized species 1+–3+ observed by characteristic NIR bands proved the predicted electronic excitation of TAA to Fc from the time-dependent DFT calculations. The degree of electron coupling in 1+–3+ decrease with the increase in aromatic conjugation (phenyl, naphthyl, and anthryl).

Probing Molecular Motions in Metal-Organic Frameworks by Three-Dimensional Electron Diffraction.

Flexible metal–organic frameworks (MOFs) are known for their vast functional diversities and variable pore architectures. Dynamic motions or perturbations are among the highly desired flexibilities, which are key to guest diffusion processes. Therefore, probing such motions, especially at an atomic level, is crucial for revealing the unique properties and identifying the applications of MOFs. Nuclear magnetic resonance (NMR) and single-crystal X-ray diffraction (SCXRD) are the most important techniques to characterize molecular motions but require pure samples or large single crystals (>5 × 5 × 5 μm3), which are often inaccessible for MOF synthesis. Recent developments of three-dimensional electron diffraction (3D ED) have pushed the limits of single-crystal structural analysis. Accurate atomic information can be obtained by 3D ED from nanometer- and submicrometer-sized crystals and samples containing multiple phases. Here, we report the study of molecular motions by using the 3D ED method in MIL-140C and UiO-67, which are obtained as nanosized crystals coexisting in a mixture. In addition to an ab initio determination of their framework structures, we discovered that motions of the linker molecules could be revealed by observing the thermal ellipsoid models and analyzing the atomic anisotropic displacement parameters (ADPs) at room temperature (298 K) and cryogenic temperature (98 K). Interestingly, despite the same type of linker molecule occupying two symmetry-independent positions in MIL-140C, we observed significantly larger motions for the isolated linkers in comparison to those reinforced by π–π stacking. With an accuracy comparable to that of SCXRD, we show for the first time that 3D ED can be a powerful tool to investigate dynamics at an atomic level, which is particularly beneficial for nanocrystalline materials and/or phase mixtures.

Preparation, characterization, and antibiofilm activity of cinnamic acid conjugated hydroxypropyl chitosan derivatives

In this study, cinnamic acid (CA) conjugated hydroxypropyl chitosan (HPCS) derivatives (HPCS-CA) with different degrees of substitution (DS) were successfully synthesized. The reaction was divided into two steps: the first step was to modify chitosan (CS) to HPCS, and the second step was to graft CA onto HPCS. Structural characterization and properties were carried out employing elemental analysis, Fourier transform infrared (FT–IR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The solubility test revealed the better water solubility of derivatives than CS. In addition, in vitro antibacterial and antibiofilm tests were performed. As expected, HPCS-CA derivatives exhibited good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The MIC and MBC of HPCS-CA derivatives could reach 256 μg/mL and 512 μg/mL, respectively. Confocal laser scanning microscopy (CLSM) analysis proved the inhibitory effect of HPCS-CA derivatives on S. aureus and E. coli biofilms by disrupting the formation of biofilms, reducing the thickness of biofilms, and the number of live bacteria. These results suggest the potential applicability of HPCS-CA derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of novel CS-based antibacterial materials.

Physicochemical Characterization and Drug Release Properties of Methyl-Substituted Silica Xerogels Made Using Sol-Gel Process.

In this work, a multi-analytical approach involving nitrogen porosimetry, small angle neutron and X-ray scattering, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, X-ray diffraction, thermal analysis and electron microscopy was applied to organically modified silica-based xerogels obtained through the sol–gel process. Starting from a tetraethoxysilane (TEOS) precursor, methyltriethoxysilane (MTES) was added to the reaction mixture at two different pH values (2.0 and 4.5) producing hybrid xerogels with different TEOS/MTES molar ratios. Significant differences in the structure were revealed in terms of the chemical composition of the silica network, hydrophilic/hydrophobic profile, particle dimension, pore shape/size and surface characteristics. The combined use of structural characterization methods allowed us to reveal a relation between the cavity dimensions, the synthesis pH value and the grade of methyl substitution. The effect of the structural properties on the controlled Captopril release efficiency has also been tested. This knowledge facilitates tailoring the pore network for specific usage in biological/medical applications. Knowledge on structural aspects, as reported in this work, represents a key starting point for the production of high-performance silica-based hybrid materials showing enhanced efficacy compared to bare silica prepared using only TEOS.

The impact of the abnormal salinity enrichment in pore water on the thermodynamic stability of marine natural gas hydrates in the Arctic region

In this study, the thermodynamic and structural characteristics of natural gas hydrates (NGHs) retrieved from gas hydrate mounds (ARAON Mound 03 (AM03) and ARAON Mound 06 (AM06)) in the Chukchi Sea in the Arctic region were investigated. The gas compositions, crystalline structure, and cage occupancy of the NGHs at AM03 and AM06 were experimentally measured using gas chromatography (GC), 13C nuclear magnetic resonance (NMR), Raman spectroscopy, and powder X-ray diffraction (PXRD). In the NGHs from AM03 and AM06, a significantly large fraction of CH4 (> 99%) and a very small amount of H2S were enclathrated in small (512) and large (51262) cages of sI hydrate. The NGHs from AM03 and AM06 were almost identical in composition, guest distributions, and existing environment to each other. The salinity of the residual pore water in the hydrate-bearing sediment (AM06) was measured to be 50.32‰, which was much higher than that of seawater (34.88‰). This abnormal salinity enrichment in the pore water of the low-permeability sediment might induce the dissociation of NGHs at a lower temperature than expected. The saturation changes in the NGHs that corresponded with an increase in the seawater temperature were also predicted on the basis of the salinity changes in the pore water. The experimental and predicted results of this study would be helpful for understanding the thermodynamic stability of NGHs and potential CH4-releasing phenomena in the Arctic region.

Effects of Substituents on the Molecular Structure and Redox Behavior of Uranyl(V/VI) Complexes with N3O2-Donating Schiff Base Ligands.

Uranyl(VI) complexes with pentadentate N3O2-donating Schiff base ligands having various substituents at the ortho (R1) and/or para (R2) positions on phenolate moieties, R1,R2-Mesaldien2-, were synthesized and thoroughly characterized by 1H nuclear magnetic resonance, infrared, elemental analysis, and single-crystal X-ray diffraction. Molecular structures of UO2(R1,R2-Mesaldien) are more or less affected by the electron-donating or -withdrawing nature of the substituents. The redox behavior of all UO2(R1,R2-Mesaldien) complexes was investigated to understand how substituents introduced onto the ligand affect the redox behavior of these uranyl(VI) complexes. As a result, the redox potentials of UO2(R1,R2-Mesaldien) in dimethyl sulfoxide increased from -1.590 to -1.213 V with an increase in the electron-withdrawing nature of the substituents at the R1 and R2 positions. The spectroelectrochemical measurements and theoretical calculation [density functional theory (DFT) and time-dependent DFT calculations] revealed that the center U6+ of each UO2(R1,R2-Mesaldien) complex undergoes one-electron reduction to afford the corresponding uranyl(V) complex, [UO2(R1,R2-Mesaldien)]-, regardless of the difference in the substituents. Consequently, the redox active center of uranyl(VI) complexes seems not to be governed by the redox potentials but to be determined by whether the LUMO is centered on a U 5f orbital or on one π* orbital of a surrounding ligand.

New insights into correlated materials in the time domain—combining far-infrared excitation with x-ray probes at cryogenic temperatures

Modern techniques for the investigation of correlated materials in the time domain combine selective excitation in the THz frequency range with selective probing of coupled structural, electronic and magnetic degrees of freedom using x-ray scattering techniques. Cryogenic sample temperatures are commonly required to prevent thermal occupation of the low energy modes and to access relevant material ground states. Here, we present a chamber optimized for high-field THz excitation and (resonant) x-ray diffraction at sample temperatures between 5 and 500 K. Directly connected to the beamline vacuum and featuring both a Beryllium window and an in-vacuum detector, the chamber covers the full (2–12.7) keV energy range of the femtosecond x-ray pulses available at the Bernina endstation of the SwissFEL free electron laser. Successful commissioning experiments made use of the energy tunability to selectively track the dynamics of the structural, magnetic and orbital order of Ca2RuO4 and Tb2Ti2O7 at the Ru (2.96 keV) and Tb (7.55 keV) L-edges, respectively. THz field amplitudes up to 1.12 MV cm−1 peak field were demonstrated and used to excite the samples at temperatures as low as 5 K.

Acautalides A-C, Neuroprotective Diels-Alder Adducts from Solid-State Cultivated Acaulium sp. H-JQSF.

The solid-state cultivation of Acaulium sp. H-JQSF isolated from Armadillidium vulgare produces acautalides A-C (1-3) as skeletally unprecedented Diels-Alder adducts of a 14-membered macrodiolide to an octadeca-9,11,13-trienoic acid. The acautalide structures, along with the intramolecular transesterifications of 1-acylglycerols, were elucidated by mass spectrometry, nuclear magnetic resonance, chemical transformation, and single-crystal X-ray diffraction. Compounds 1-3 were found to be neuroprotective with antiparkinsonic potential in the 1-methyl-4-phenylpyridinium-challenged nematode model, with the magnitude impacted by the glycerol esterification.

Magnetic order and 5d1 multipoles in a rhenate double perovskite Ba2MgReO6

Structural and magnetic transitions in a double perovskite hosting 5d1 Re ions are discussed on the basis of recently published high-resolution x-ray diffraction patterns [D. Hirai, et al., Phys. Rev. Res. 2, 022063(R) (2020)]. A reported structural transition below room temperature, from cubic to tetragonal symmetry, appears not to be driven by T2g-type quadrupoles, as suggested. A magnetic motif at lower temperature is shown to be composed of two order parameters, associated with propagation vectors k = (0, 0, 1) and k = (0, 0, 0). Findings from our studies, for structural and magnetic properties of Ba2MgReO6, surface in predicted amplitudes for x-ray diffraction at rhenium L2 and L3 absorption edges, and magnetic neutron Bragg diffraction. Specifically, entanglement of anapole and spatial degrees of freedom creates a quadrupole in the neutron scattering amplitude. It would be excluded in an unexpected scenario whereby the rhenium atomic state is a manifold. Also, a chiral signature visible in resonant x-ray diffraction will be one consequence of predicted electronic quadrupole and magnetic dipole orders. A model Re wave function consistent with all current knowledge is a guide to electronic and magnetic multipoles engaged in x-ray and neutron diffraction investigations.

One pot synthesis of new cross-linked chitosan-Schiff' base: Characterization, and anti-proliferative activities

Four novel chitosan hydrogels were successfully synthesized through the cross-linking reaction of chitosan with different concentrations of ethyl 5-(3,5-dihydroxy-1,4-dioxan-2-yl)-2-methylfuran-3-carboxylate. Their structures were confirmed by Fourier transform infrared spectroscopy (FT-IR), 13C Cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS 13C NMR), ultraviolet-visible spectroscopy, thermogravimetric analysis (TGA, DTA), and X-ray diffraction (XRD). Cytotoxicity on hepatocellular carcinoma (HepG-2) cell line and a normal African green monkey kidney (Vero) cell line were studied using the MTT assay. The resultant hydrogels showed a good inhibitory effect comparing to the un-modified parent; the hydrogels with the lowest degree cross-linking (0.125 and 0.25 mol cross-linker per one chitosan residue) showed potent anticancer activity in the HepG2 cells with IC50 of 57.9 and 80.9 μg/ml, respectively. These results show that the newly synthesized cross-linked chitosan derivatives demonstrated more selectivity to the HepG2 than the Vero cells, indicating its potential for Investigation in the cure of hepatocellular carcinoma.

NMR Study of LiCo0.96Al0.04O2 As a Positive Electrode Material for Li-Ion Batteries: Homogeneity and Role of Doping on Mechanisms

LiCoO2 (LCO) is one of the most widely used positive electrode materials in lithium-ion batteries due to its high volumetric energy density which can be further improved by charging at high voltages. However, working at high potential (above 4.3 V vs. Li+/Li) causes a deterioration in cycling performance induced by structural instabilities, electrolyte oxidation and Co dissolution. Extensive studies have been devoted to increasing energy density by increasing the cutoff voltage. The substitution of cobalt with various metals is one of the classic methods, the choice of aluminum as dopant for example is based on several criteria: low cost and non-toxicity, a similar radius for Al3+ compared to Co3+ (0.535 Å vs. 0.545 Å) facilitates the replacement of the latter and maintains the structure leading to the complete solid solution LiCo1-yAlyO2.We will focus here on LiCo0.96Al0.04O2, synthesized by the solid route and characterized by 7Li, 27Al and 59Co Nuclear Magnetic Resonance (NMR) and synchrotron X-Ray Diffraction (XRD). In addition to the characterization of the mean structure by XRD, the NMR allows us to study the local environments of the different nuclei. 27Al MAS NMR and synchrotron XRD studies revealed that the Al-doping in this material is homogeneous. 7Li MAS NMR indicates that its stoichiometry (Li/M=1.00) is ideal. The electrochemical study has shown that the phase transitions occurring during delithiation of LiCoO2, were partially eliminated by aluminum doping even with a low doping amount and the high potential mechanisms appear to be different. In order to better understand the role of Al-doping on the mechanisms involved during cycling, several phases LixCo0.96Al0.04O2 were prepared by electrochemical deintercalation and studied by 7Li, 59Co, and 27Al NMR and by XRD.During lithium deintercalation, Co3+ is oxidized to Co4+ then one unpaired electron is generated in the t2g band of Co atoms (t2g 5eg 0). For 0.8 ≤ x ˂ 1.00 the 7Li MAS NMR shows that the system behaves locally as two phase domain: domain with localized electrons and domain with delocalized ones on Con+ ions (Knight shift), even for very low amount of deintercalation (x=0.98), thus the XRD results confirm the existence of the biphasic domain. Whereas, a single phase domain is observed for the deintercalated materials with 0.4 ≤ x ≤ 0.8 and also at the NMR time of scale a single signal (Knight shift) is observed. This signal increases in intensity at the expense of 0 ppm and shifts to the higher isotropic displacement values up to x=0.5 then decreases, thus the evolution of the chex lattice parameter is correlated with the signal shift. For x = 0.3 and x = 0.2: a new broad signal appears probably due to formation of new Li environment in stacking faulted layers (O1 type). These different contributions will be more detailed on the presentation.

Chirality and magnetic quadrupole order inPb(TiO)Cu4(PO4)4probed by interference scattering in resonant x-ray diffraction

Circular dichroism observed by resonant x-ray diffraction at the $\mathrm{Cu}\phantom{\rule{0.16em}{0ex}}{L}_{3}$ edge was investigated in a chiral antiferromagnet, $\mathrm{Pb}(\mathrm{TiO}){\mathrm{Cu}}_{4}{({\mathrm{PO}}_{4})}_{4}$, which shows magnetic quadrupole order $({T}_{\mathrm{N}}=7\phantom{\rule{0.16em}{0ex}}\mathrm{K})$. At temperatures above ${T}_{\mathrm{N}}$, space-group-forbidden reflection 100 is observed due to the anisotropic tensor of susceptibility (ATS) scattering. With decreasing temperature, the reflection intensity shows substantial circular dichroism below ${T}_{\mathrm{N}}$. We found one-to-one correspondence between the sign of the circular dichroism and that of the sample's crystallographic chirality. In addition, the reflection intensity depends on the product of poling magnetic and electric fields. The circular dichroism observed in this study is interpreted as the interference between the ATS and the magnetic scatterings. This finding shows that the interference scattering probes both the chirality and the order parameter of the magnetic quadrupole order in this chiral antiferromagnet.