X-ray Laser Research Articles

Electrochemical carboxylation: Green synthesis of atrolactic acid using boron-doped diamond electrodes

Electrochemical CO2 fixation is vital for sustainability in the chemical industry, yet the selective synthesis of multi-carbon products remains challenging. Organic electrosynthesis offers promise by enabling precise control over reaction conditions and facilitating novel reactivity patterns. One such technique, electrochemical carboxylation, involves coupling CO2 with organic molecules to produce carboxylic acids. Specifically, electro-carboxylation of acetophenone yields atrolactic acid, a valuable precursor for nonsteroidal anti-inflammatory drugs, providing a greener alternative to traditional production methods. This study focuses on the synthesis and characterization of boron-doped diamond (BDD) films using the microwave plasma-assisted chemical vapor deposition (MP-CVD) method and synthesized BDD electrodes were then used for the electrolytic carboxylation of acetophenone. Various analytical techniques, including X-ray diffraction (XRD), Raman spectroscopy, and laser microscopy, etc. were employed to characterize the BDD films. Various BDD films synthesized for different durations were utilized in the electrolytic carboxylation of acetophenone, with the highest yield of atrolactic acid (25 %) achieved using a BDD film synthesized over 6 h. Also, the effect of BDD surface modification i.e. oxygen and hydrogen terminated BDD on the synthesis of atrolactic acid was studied. Additionally, different electrolytes were employed in the synthesis process of atrolactic acid. A comparative study between Pt and BDD electrodes for the electrolytic carboxylation of acetophenone was conducted, and a mechanism for the formation of atrolactic acid was proposed.

Origin and distribution of clay minerals in semi-arid Sahelian soils: case of Kori Ouallam watershed, south-western Niger

Abstract This study examines the origin and distribution of clay minerals of the pedological horizons of Kori Ouallam watershed (south-western Niger). It is based on field sampling campaigns and a series of laboratory analyses. A total of 49 samples were analysed, 28 from surface horizons (0–10 cm depth) and 21 from pedological profiles (0–1 m depth). The samples were analysed by X-ray diffraction on bulk and clay (<2 μm) fractions, X-ray fluorescence spectrometry, laser granulometry, organic matter and calcium carbonate content, macroscopic observations (binocular loupe) and scanning electron microscopy equipped with an energy-dispersive spectrometry system. The pedological horizons are characterized by low organic matter contents (<1%) and no calcium carbonate. The particle-size distribution shows net textural differentiation, with a predominance of sandy loam to sandy clay loam textures in the upper horizons and clay loam to clay in the deep horizons. The main major oxides were SiO2 (46.3–89.0%), Al2O3 (5.0–24.2%) and Fe2O3 (1.0–27.9%). Kaolinite (64–98%) is the predominant clay mineral at all horizons, associated with low to moderate proportions of illite (1–34%) and traces of chlorite. Kaolinite is essentially inherited from the parent rock, whereas illite results from chemical alteration by bisialitization of the primary minerals initially rich in potassium feldspar contained in the parent rock. However, soil texture and organic matter vary independently with clay mineralogy. An extended study of all of the pedological facies that make up south-western Niger, combined with supplementary analyses, would further improve our understanding of clay mineralogy in the Sahelian zone.

Ultrafast X-ray laser-induced explosion: How the depth influences the direction of the ion trajectory

Single particle imaging using X-ray lasers is a technique aiming to capture atomic resolution structures of biomolecules in their native state. Knowing the particle's orientation during exposure is crucial for method enhancement. It has been shown that the trajectories of sulfur atoms in a Coulomb exploding lysozyme are reproducible, providing orientation information. This study explores if sulfur atom depth influences explosion trajectory. Employing a hybrid collisional-radiative/molecular dynamics model, we analyze the X-ray laser-induced dynamics of a single sulfur ion at varying depths in water. Our findings indicate that the ion spread-depth relationship depends on pulse parameters. At a photon energy of 2 keV, high-charge states are obtained, resulting in an increase of the spread with depth. However, at 8 keV photon energy, where lower charge states are obtained, the spread is essentially independent with depth. Finally, lower ion mass results in less reproducible trajectories, opening a promising route for determining protein orientation through the introduction of heavy atoms.

Оценка влияния вредных факторов производственной среды в литейном цехе

Harmful factors in the working area of foundry operators are considered. The complexity of workflows affects the quality of air in the foundry. The casting process is accompanied by the generation of a significant amount of dust as well as high levels of noise and vibration. The relevant aspect of the study is the assessment of the state of occupational safety, considering the harmful factors at the production in question. Dust content has been thoroughly investigated by dispersive and elemental analysis of dust using X-ray fluorescence analysis and laser diffraction. The impact of the vibroacoustic factor has been studied. An analysis of the sound pressure level in the working areas of the foundry has been provided. The authors have proposed technical measures to reduce dust content and the level of impact of the vibroacoustic factor. The development of a system of measures to minimize harmful impact has been based on a combined analysis of factors. Methods to reduce noise and dust content at workplaces are proposed as follows: organizing a highly efficient system of post-treatment of dust emissions, increasing equipment sound absorption, installing structures to reduce noise pollution, and using a coating system made of dense rubber structures (compounds). Ensuring safe working conditions in working areas of the foundry has been studied; the improvement of working conditions due to the improvement of existing and installation of new noise and vibration protection means has been proposed. An integrated approach to the assessment of production factors has been provided, which has been the key element for the development of engineering and organizational protection measures. The integrated analysis helped identify the degree of impact of harmful factors such as noise, and dust content on machine operators during the casting process and to conduct a comparative assessment of sound pressure levels. The sound pressure can be reduced by 8–10 dB using improved mechanisms of shot-blasting chamber operator protection. More extensive dust protection measures are proposed due to the sample content of 85% of the dust mass less than 100 microns and multicomponent dust with a high content of silicon and iron. The findings provide a technical value for the substantiation of the modernization of noise and dust reduction systems at foundry operator workplaces.

X-ray and photoelectron spectroscopy of surface chemistry; from bonding via femtosecond to operando

For the 60th anniversary of Surface Science, I present here a personal account of some of the most significant contributions I have made to the field over the past three decades. The utilisation of X-rays serves as the foundation for these studies, encompassing X-ray spectroscopy for the mapping of surface chemical bonds, probing of surface reactions on ultrafast timescales, and X-ray photoelectron spectroscopy under operando conditions. The direct projection of electronic states onto the adsorbed atom allowed the detection of bonding and anti-bonding states within the d-band model. The selective probing of orbitals of different symmetries on the two atoms in adsorbed N2 provided a fundamental understanding of the nature of diatomic bonding to surfaces. Ultrafast optical pumping and X-ray laser techniques allowed the study of CO undergoing desorption leading to the observation of the precursor state. Pump-probed studies of co-adsorbed CO and O on Ru enabled the means to detect transition state species during catalytic CO oxidation. The use of operando X-ray photoelectron spectroscopy at near-atmospheric pressures opened the door to probe the surface chemistry and gain insight into the reaction mechanism during hydrogenation reactions to produce ammonia, hydrocarbons, methanol and ethanol. By inserting an electrochemical cell into the spectroscopic chamber, both fuel cell and water splitting electrocatalysis could be studied giving insight about the reaction mechanism.

Using a multiple regression model for predicting the soft X-ray laser gain coefficient from laser plasmas

Using a multiple regression model for predicting the soft X-ray laser gain coefficient from laser plasmas

Fully relativistic energies, transition properties, and lifetimes of lithium-like germanium

Abstract Employing two fully relativistic methods, the multi-reference configuration Dirac–Hartree–Fock (MCDHF) method and the relativistic many-body perturbation theory (RMBPT) method, we report energies and lifetime values for the lowest 35 energy levels of the (1s2)nl configurations (where the principal quantum number n = 2–6 and the angular quantum number l = 0, …, n–1) of lithium-like germanium (Ge XXX), as well as complete data on the transition wavelengths, radiative rates, absorption oscillator strengths, and line strengths between the levels. Both the allowed (E1) and forbidden (magnetic dipole M1, magnetic quadrupole M2, and electric quadrupole E2) ones are reported. The results from the two methods are consistent with each other and align well with previous accurate experimental and theoretical findings. We assess the overall accuracies of present RMBPT results to be likely the most precise ones to date. The present fully relativistic results should be helpful for soft x-ray laser research, spectral line identification, plasma modeling and diagnosing. The datasets presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00135.

Comparing single-shot damage thresholds of boron carbide and silicon at the European XFEL.

Xray free-electron lasers (XFELs) enable experiments that would have been impractical or impossible at conventional X-ray laser facilities. Indeed, more XFEL facilities are being built and planned, with their aim to deliver larger pulse energies and higher peak brilliance. While seeking to increase the pulse power, it is quintessential to consider the maximum pulse fluence that a grazing-incidence FEL mirror can withstand. To address this issue, several studies were conducted on grazing-incidence damage by soft X-ray FEL pulses at the European XFEL facility. Boron carbide (B4C) coatings on polished silicon substrate were investigated using 1 keV photon energy, similar to the X-ray mirrors currently installed at the soft X-ray beamlines (SASE3). The purpose of this study is to compare the damage threshold of B4C and Si to determine the advantages, tolerance and limits of using B4C coatings.

New approaches in the tomographic visualization of joints using X-ray contrast nanoparticles and laser radiation

New approaches in the tomographic visualization of joints using X-ray contrast nanoparticles and laser radiation

Free electrons spin-dependent Kapitza–Dirac effect in two-dimensional triangular optical lattice

Abstract The free electron spin dynamics in Kapitza–Dirac (KD) effect had been studied theoretically in one-dimensional standing wave of EUV to X-ray laser with extremely high intensity, which is far beyond experimental realization. Here, we propose to achieve the free electron spin-dependent KD effect in two-dimensional triangular optical lattice with spatial inversion symmetry breaking, and the theoretical results reveal that laser with wavelength in visible or near-IR and five orders of magnitude decreased intensity could lead to obvious spin-dependent KD effect. This work provides the way to realize the free electron spin-dependent KD effect experimentally.

Application of Recycled Ultrafiltration Membranes in an Aerobic Membrane Bioreactor (aMBR): A Validation Study.

A validation study using recycled ultrafiltration membranes (r-UF) on an aerobic membrane bioreactor (aMBR) was conducted for the first time. Four different polyethersulfone (PES) membranes were tested using synthetic urban wastewater (COD 0.4-0.5 g/L) during two experimental periods: (i) recycled ultrafiltration membrane (r-UF) and commercial UF membrane (molecular weight cut-off (MWCO) 150 kDa) (c-150 kDa); (ii) r-UF membrane modified by dip-coating using catechol (CA) and polyethyleneimine (PEI) (mr-UF) and c-20 kDa membrane. Permeability, fouling behavior, and permeate quality were evaluated. Extensive membrane characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX), and confocal laser scanning microscopy (CLSM). Permeate quality for r-UF and mr-UF membranes was excellent and comparable to that obtained using commercial membranes under similar conditions. Additionally, r-UF and mr-UF membranes presented a steadier performance time. Additionally, r-UF membrane demonstrated less tendency to be fouled (Rf, m-1) r-UF 7.92 ± 0.57 × 1012; mr-UF 9.90 ± 0.14 × 1012, c-150 kDa 1.56 ± 0.07 × 1013 and c-20 kDa 1.25 ± 0.50 × 1013. The r-UF membrane showed an excellent antibiofouling character. Therefore, r-UF membranes can be successfully implemented for wastewater treatment in aMBR, being a sustainable and cost-effective alternative to commercial membranes that can contribute to overcome membrane fouling and membrane replacement issues.

Power Density Titration of Reversible Photoisomerization of a Fluorescent Protein Chromophore in the Presence of Thermally Driven Barrier Crossing Shown by Quantitative Millisecond Serial Synchrotron X-ray Crystallography.

We present millisecond quantitative serial X-ray crystallography at 1.7 Å resolution demonstrating precise optical control of reversible population transfer from Trans-Cis and Cis-Trans photoisomerization of a reversibly switchable fluorescent protein, rsKiiro. Quantitative results from the analysis of electron density differences, extrapolated structure factors, and occupancy refinements are shown to correspond to optical measurements of photoinduced population transfer and have sensitivity to a few percent in concentration differences. Millisecond time-resolved concentration differences are precisely and reversibly controlled through intense continuous wave laser illuminations at 405 and 473 nm for the Trans-to-Cis and Cis-to-Trans reactions, respectively, while the X-ray crystallographic measurement and laser illumination of the metastable Trans chromophore conformation causes partial thermally driven reconversion across a 91.5 kJ/mol thermal barrier from which a temperature jump between 112 and 128 K is extracted.

MolDStruct: Modeling the dynamics and structure of matter exposed to ultrafast x-ray lasers with hybrid collisional-radiative/molecular dynamics.

We describe a method to compute photon-matter interaction and atomic dynamics with x-ray lasers using a hybrid code based on classical molecular dynamics and collisional-radiative calculations. The forces between the atoms are dynamically determined based on changes to their electronic occupations and the formation of a free electron cloud created from the irradiation of photons in the x-ray spectrum. The rapid transition from neutral solid matter to dense plasma phase allows the use of screened potentials, reducing the number of non-bonded interactions. In combination with parallelization through domain decomposition, the hybrid code handles large-scale molecular dynamics and ionization. This method is applicable for large enough samples (solids, liquids, proteins, viruses, atomic clusters, and crystals) that, when exposed to an x-ray laser pulse, turn into a plasma in the first few femtoseconds of the interaction. We present four examples demonstrating the applicability of the method. We investigate the non-thermal heating and scattering of bulk water and damage-induced dynamics of a protein crystal using an x-ray pump-probe scheme. In both cases, we compare to the experimental data. For single particle imaging, we simulate the ultrafast dynamics of a methane cluster exposed to a femtosecond x-ray laser. In the context of coherent diffractive imaging, we study the fragmentation as given by an x-ray pump-probe setup to understand the evolution of radiation damage in the time range of hundreds of femtoseconds.

Higher order quantum waves in fractal dimensions from nonlocal complex derivative operator

In this study, we introduced a new nonlocal complex derivative operator in fractal dimension based concurrently on the concept of “nonlocal generalized complex backward-forward coordinates” and the “product-like fractal measure”. The quantization of the theory in fractal dimension leads to a higher order Schrödinger equation characterized by a higher order energy operator. As an illustration, we have discussed the cases of infinite quantum well and power-law potentials. Their associated zero-point energies were found to depend on the numerical value of the fractal dimension. For the infinite well, the decrease in zero-point energy with fractal dimension may result in the emission of large wavelengths photons observed experimentally in X-ray laser bursts emitted from the solid.

Theoretical Studies of Anisotropic Melting of Ice Induced by Ultrafast Nonthermal Heating.

Water and ice are routinely studied with X-rays to reveal their diverse structures and anomalous properties. We employ a hybrid collisional-radiative/molecular-dynamics method to explore how femtosecond X-ray pulses interact with hexagonal ice. We find that ice makes a phase transition into a crystalline plasma where its initial structure is maintained up to tens of femtoseconds. The ultrafast melting process occurs anisotropically, where different geometric configurations of the structure melt on different time scales. The transient state and anisotropic melting of crystals can be captured by X-ray diffraction, which impacts any study of crystalline structures probed by femtosecond X-ray lasers.

Sub-photon accuracy noise reduction of a single shot coherent diffraction pattern with an atomic model trained autoencoder

Single-shot imaging with femtosecond X-ray lasers is a powerful measurement technique that can achieve both high spatial and temporal resolution. However, its accuracy has been severely limited by the difficulty of applying conventional noise-reduction processing. This study uses deep learning to validate noise reduction techniques, with autoencoders serving as the learning model. Focusing on the diffraction patterns of nanoparticles, we simulated a large dataset treating the nanoparticles as composed of many independent atoms. Three neural network architectures are investigated: neural network, convolutional neural network and U-net, with U-net showing superior performance in noise reduction and subphoton reproduction. We also extended our models to apply to diffraction patterns of particle shapes different from those in the simulated data. We then applied the U-net model to a coherent diffractive imaging study, wherein a nanoparticle in a microfluidic device is exposed to a single X-ray free-electron laser pulse. After noise reduction, the reconstructed nanoparticle image improved significantly even though the nanoparticle shape was different from the training data, highlighting the importance of transfer learning.

On the self-assembly of polarization domain observed in the relaxor ferroelectric Pb[(Mg1/3Nb2/3)0.722Ti0.278]O3

Self-assembly of polarization domain in relaxor-ferroelectrics Pb[(Mg1/3Nb2/3)0.722Ti0.278]O3 is discussed based on the observation of the coherent soft X-ray laser reflection. We investigate the autocorrelation of the polarization domain at the early stage of evolution. Local order of the polarization domain become in phase and periodic over 600 μm as the temperature of the crystal cool down to 383 K keeping with almost thermal equilibrium condition. Minimum domain formation free energy is discussed qualitatively.

Milling amorphous FeSiB ribbons with vibratory ball and disc mills

Fe, Si and B powders, mixed with atomic composition Fe78Si9B13, are subjected after arc melting to a melt spinning process, which is optimized to obtain the greatest amount of amorphous ribbon. The amorphous ribbons are milled to powder form in a vibratory ball mill and a vibratory disc mill, taking care of maintaining the amorphous character. Ribbons and powders have been characterized by X-ray diffraction (XRD), laser diffraction, SEM and TEM microscopy, and differential scanning calorimetry (DSC). The amorphous character and particle size of the powders are characterized as a function of the mill charge and the milling time. It is shown that the use of the ball mill is appropriate for obtaining small quantities of amorphous or nanocrystalline powder, while the disc mill can process larger quantities of powder in a shorter time. The particle sizes obtained for milling times between 10 and 150 min range between 26 and 412 μm, ready for use in powder metallurgy processes.

New Approaches in the Tomographic Visualization of Joints Using X-ray Contrast Nanoparticles and Laser Radiation

New Approaches in the Tomographic Visualization of Joints Using X-ray Contrast Nanoparticles and Laser Radiation

Capillary discharge in the high repetition rate regime

Plasma discharge in the capillary is used to develop x-ray lasers, waveguides for high power laser pulses, and as active plasma lenses to focus high energy charged particle beams. Capillary discharges in the high repetition rate regime are of interest for applications that require large average values, such as luminosity and/or electric current of laser accelerated particles. In the present paper, we study the capillary discharge in the high repetition rate regime in connection with the ultrashort laser pulse guiding for laser electron acceleration. Using magnetohydrodynamic computer simulations and theoretical scaling, we investigate the filling of the capillary with the gas, the electric discharge development leading to outflow of the plasma from the capillary, and the recovery of gas distribution after the discharge end. In the next cycle, these processes are repeated. As a result, we found the characteristic cycle time, which determines the upper limit on the repetition rate allowed by the capillary parameters. In the case of the capillary discharges used for acceleration of sub-GeV electron beams, e.g., needed for compact free electron lasers, an upper limit on the repetition rate is approximately equal to 10 kHz. Published by the American Physical Society 2024