Hydrogen Spectroscopy Research Articles

Synthesis and properties of a new environmentally friendly bicyclic imidazoline quaternary ammonium salt as a corrosion inhibitor of carbon steel

Abstract A new corrosion inhibitor, environment-friendly bicyclic imidazoline quaternary ammonium salt (DL-IM), was synthesized using DL-aspartic acid, hydroxyethyl ethylenediamine, and benzyl chloride as the main raw materials. The amidation, cyclization, and quaternization reactions were carried out at 140 °C for 4 h, 220 °C for 3 h, and 70 °C for 3 h, respectively. The structure of DL-IM was characterized by infrared spectroscopy and nuclear magnetic hydrogen spectroscopy. The corrosion experiments of carbon steel sheets (American Petroleum Institute, API 5CT N80, primarily used in well drilling operations to protect the wellbore), protected with or without DL-IM, demonstrated that DL-IM had a good anti-corrosion performance (with the inhibition efficiency and corrosion rate of 97.13% and 0.6528 mm/a, respectively) in the 1 M HCl solution at 60 °C. DL-IM was a kind of cathodic protection-type corrosion inhibitor confirmed by Tafel curves. The analysis of adsorption kinetics by quantum chemical simulations demonstrated that the imidazoline ring in the DL-IM molecule can form covalent bonds with the empty d-orbitals of Fe through charge sharing. Moreover, the dipole moment of DL-IM is 1.3931 D (1 D = 3.34×10-30 C·m), suggesting a good hydrophobicity of DL-IM. Therefore, the adsorption film formed by DL-IM on the surface of N80 can effectively isolate the corrosive medium from N80. Thus, successful synthesis of DL-IM provides a new insight into the design and synthesis of the environment-friendly corrosion inhibitor with stronger corrosion inhibition effect.

Laser excitation of the 1S–2S transition in singly-ionized helium

Laser spectroscopy of atomic hydrogen and hydrogen-like atoms is a powerful tool for tests of fundamental physics. The 1S–2S transition of hydrogen in particular is a cornerstone for stringent Quantum Electrodynamics (QED) tests and for an accurate determination of the Rydberg constant. We report laser excitation of the 1S–2S transition in singly-ionized helium (3He+), a hydrogen-like ion with much higher sensitivity to QED than hydrogen itself. The transition requires two-photon excitation in the challenging extreme ultraviolet wavelength range, which we achieve with a tabletop coherent laser system suitable for precision spectroscopy. The transition is excited by combining an ultrafast amplified pulse at 790 nm (derived from a frequency comb laser) with its 25th harmonic at 32 nm (produced by high-harmonic generation). The results are well described by our simulations and we achieve a sizable 2S excitation fraction of 10−4 per pulse, paving the way for future precision studies.

Effect of Modification by β-Amylase and α-Glucosidase on the Structural and Physicochemical Properties of Maize Starch.

Single enzymatic modifications are limited to starch. Complex modification with synergistic amylases will improve starch properties more significantly. In this study, maize starch was compound modified by β-amylase and α-glucosidase. The structure and physicochemical properties of the corn starch were determined by scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance hydrogen spectroscopy (1HNMR), high-performance anion-exchange chromatography (HPAEC-PAD), differential scanning calorimetry (DSC) and Rapid Visco analyzer (RVA) to determine the changes in the structure and physicochemical properties of maize starch before and after the dual enzyme modification. The branching degree (4.95-7.10%) of maize starch was increased after bi-enzymatic modification, the amylose content (28.77-18.60%) was decreased, and the amylopectin content (70.79-81.71%) was elevated. The relative crystallinity (20.41-30.20%) and short-range ordered structure of the starch increased, and the dual enzyme modification led to a more compact structure. Dual enzyme-modified maize starch showed a decrease in long chains, an increase in short chains, and its degree of branching was elevated. Dual enzyme modification also affected the thermal stability, pasting, light transmittance (1.40-2.16%), solubility (20.15-13.76%), and swelling (33.97-45.79%) of maize starch. It can be concluded that the complex modification of maize starch by β-amylase and α-glucosidase significantly changed the amylose/amylopectin ratio of the starch and made its structure denser. These results can provide a theoretical basis for the enzymatic preparation of maize starch with different amylose/amylopectin ratios and the development and utilization of functional starches.

Narrow resonances in Rydberg hydrogen spectroscopy

Narrow resonances in Rydberg hydrogen spectroscopy

Electron temperature characterization of H2 processing plasma by optical emission spectroscopy

Optical emission spectroscopy of hydrogen (H2) plasma is performed to characterize the electron temperature, T e . The H2 Fulcher band emission and radiative dissociation continuum are measured, where the Fulcher band emission is recognized to be T e -sensitive, compared with the dissociation continuum. With this T e -sensitive nature, a simple way of determining T e is proposed, specifically using the intensity ratio of the Fulcher band emission to dissociation continuum. The T e determination is demonstrated for H2 processing plasmas generated by capacitively coupled discharges at different gas pressures.

Diffusion and Spectroscopy of H2 in Myoglobin

The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H2) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, and the vibrational spectroscopy was investigated using conventional empirical energy functions and improved models able to describe higher-order electrostatic moments of the ligand. Depending on the energy function used, H2 can occupy the same internal defects as already found for Xe or CO (Xe1 to Xe4 and B-state). Furthermore, four additional sites were found, some of which had been discovered in earlier simulation studies. Simulations using a model based on a Morse oscillator and distributed charges to correctly describe the molecular quadrupole moment of H2 indicate that the vibrational spectroscopy of the ligand depends on the docking site it occupies. This is consistent with the findings for CO in Mb from experiments and simulations. For H2, the maxima of the absorption spectra cover ∼20 cm−1 which are indicative of a pronounced Stark effect of the surrounding protein matrix on the vibrational spectroscopy of the ligand. Electronic structure calculations show that H2 forms a stable complex with the heme iron (stabilized by ∼−12 kcal/mol), but splitting of H2 is unlikely due to a high activation energy (∼50 kcal/mol).

Lignin‐based nitrogen and phosphorus‐containing polylactic acid with flame‐retardant performances

AbstractPolylactic acid (PLA) is a new type of biodegradable material that has been applied in many fields such as extrusion, injection molding, film drawing, and spinning. In contrary, it does not have flame retardancy. In this paper, N‐PCDL was synthesized by amidation reaction between COOH of PCDL and NH2 of tetraethylenepentamine (TEPA), followed by an Atherton‐Todd reaction of unreacted NH2 at the other end of TEPA with PH of DOPO to prepare a novel lignin‐based flame retardant containing nitrogen and phosphorus (NP‐PCDL). The Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic hydrogen spectroscopy (1H NMR) analysis results showed that proton peaks of CONH, PN, and NH appeared in the NP‐PCDL spectrum, while the characteristic absorption peak of PH bond disappeared in DOPO, the X‐ray photoelectron spectroscopy (XPS) results showed that the degraded lignin consisted of elements C and O, while NP‐PCDL consisted of elements C, O, N and P. The above results indicated that NP‐PCDL was successfully prepared. NP‐PCDL accounted for 3% (mass percentage, the same below), 5% and 10% of PLA, then lignin based flame‐retardant PLA composites were prepared by internal mixing and injection molding. Thermogravimetric analysis (TGA) showed that the residual carbon of PLA/3% NP‐PCDL, PLA/5% NP‐PCDL and PLA/10% NP‐PCDL at 800°C were higher than that of pure PLA, with the increase of 56.56%, 97.54%, and 301.64%, respectively; The analysis of SEM, XPS, and Raman showed that PLA/NP‐PCDL formed dense, regular and highly graphitized residual carbon with phosphorus nitrogen structure during the combustion process. At the same time, NH3, H2O and PO˙ free radicals were released, which could dilute combustible gases, destroy free radical chain reaction, isolate combustible gases and heat, so as to play a flame‐retardant role.

A novel and sustainable approach to efficiently modify cotton material via a physical flash-explosion with sub- or SCF-CO2 as medium

A novel and eco-friendly approach to modify natural cotton fiber by flash-explosion with a sub- or supercritical fluid of carbon dioxide (sub- or SCF-CO2) for improving its structure and properties was constructed for the first time. The achieved results demonstrate that remarkable improvements in the coloration performance of cotton fiber by 71.1 % and the water retention by 1001.2 % against the control could be readily available by employing the flashily-explosion method at a recommended condition with 4-cycle explosion in sub- or SCF-CO2, and system temperature, fluid treatment duration and explosion number exhibited much more pronounced positive influences among all parameters. Additionally, minimal influences from the supercritical explosion on cotton fiber micronaire value, thermal property and tensile breaking strength were also observed. The scanning electron microscopy (SEM) and porosity investigations clearly show that plenty of micropores and/or strip fissures were formed on the fiber surfaces and their inner phases, and notably improved fiber surface area, pore volume and size were also obtained after a subsupercritical flash-explosion. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) analysis disclose that numbers of hydrogen bonds between the fiber macrochains and/or from their intramolecular chains were broken by generating numerous free hydroxyl groups, which reasonably supported the improvements of the dye uptake behaviors and water retention properties, etc. The Energy-dispersive X-ray spectroscopy (EDS) analysis on the fiber cross-sections further confirms that a loosening of the inner aggregation structure of the cotton fiber was achieved after a flash explosion by significantly enhancing its coloration performance, etc. This innovative approach provides a promising idea and possibility as an alternative to chemical methods via mechanically and physically modifying fiber or other materials with sub- or SCF-CO2 fluid in an eco-friendly and sustainable manner.

A novel biobased prepreg from flax and thermosetting poly(lactic acid): Synthesis, curing and processing

Flax fiber-reinforced thermosetting poly (lactic acid) (PLA) composites, a fully degradable plant fiber-reinforced composites, were prepared by hot-melt pre-impregnation, which consists of two processes, the preparation and curing of the prepreg. Firstly, thermosetting PLA with intrinsic flame-retardancy was synthesized and its molecular structure was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The non-isothermal viscosity of the thermosetting PLA resin system was investigated to determine the film-formation temperature (55°C) and the impregnation temperature (65°C) during the preparation of the prepreg. On this basis, novel flax fiber-reinforced thermosetting PLA prepreg was prepared and its curing kinetics was investigated using differential scanning calorimetry (DSC). A curing simulation model of the prepreg was developed using the finite difference method, which was used to design and optimize the curing cycle of the flax fiber-reinforced thermosetting PLA prepreg. Finally, the flax fiber-reinforced thermosetting PLA composites with different lay-ups were prepared using the optimal curing cycles and their mechanical and flame retardant properties were investigated, with tensile and flexural strengths up to 128 MPa and 98.8 MPa, and flame retardant ratings up to UL-94 V-1. Overall, the results of this study can provide an important basis for expanding the application of flax fiber reinforced thermosetting PLA composites.

Synthesis and performance study of amphoteric polymer suspension stabilizer for cementing slurry at ultra-high temperature

As the number of ultra-deep wells increases, maintaining the suspension stability of cement slurry at ultra-high temperatures becomes increasingly challenging; the development of a suspension stabilizer suitable for ultra-high temperature environments is imperative. Therefore, this study synthesized a temperature-resistant polymer suspension stabilizer (LHAP) using 2-acrylamide-2-methylpropanesulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAA), 4-acryloylmorpholine (ACMO), and quaternary ammonium cationic hydrophobic long-chain monomer hexadecyl dimethylallyl ammonium chloride (DMAAC-16) as raw materials. It was applied to maintain the suspension stability of cement slurry at ultra-high temperatures. The molecular structure and molecular weight of LHAP were characterized and tested using infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, and Ubbelohde viscometer. The thermal stability and viscosity-temperature performance of LHAP were measured using thermogravimetric analysis and rheometer, respectively. Through the segmented density difference testing of cement stone columns, the suspension stability effect of LHAP on cement slurry under high temperature was evaluated. The suspension stabilization mechanism of LHAP was studied through fluorescence probe testing, variable temperature UV visible light testing, variable temperature particle size distribution testing, Zeta potential analysis, Environmental Scanning Electron Microscopy (ESEM) analysis, and scanning electron microscopy (SEM) analysis. The results indicated that the polymer suspension agent LHAP had excellent temperature resistance, and the molecules didn’t undergo significant thermal degradation below 302 ℃. At high temperatures of 220 ℃, LHAP could maintain the suspension stability of cement slurry, and the segmented density difference of cement columns was less than 0.01 g/cm3. Mechanism analysis revealed that in addition to enhancing temperature resistance by introducing sulfonic acid groups and rigid rings, LHAP also effectively maintains the stability of the slurry suspension at ultra-high temperatures by coordinating electrostatic interactions and molecular associations. LHAP can effectively solve the settlement instability problem of cement slurry under ultra-high temperature, which is beneficial for improving the safety and quality of cementing construction in ultra-deep wells.

Fundamental physicochemical properties, intermolecular interactions and CO2 absorption properties of binary mixed solutions of monoethanolamine + diethylenetriamine

This work presents experimental data on the density (ρ), viscosity (η), and surface tension (γ) of monoethanolamine (MEA), diethylenetriamine (DETA), and their binary mixed solutions across 298.15–318.15 K. Using these physicochemical data, the work also explored properties like excess molar volume (VmE) and viscosity deviation (Δη) of the solutions. The experimental results were modeled using the Jouyban-Acree model, McAllister four-body model, and Redlich-Kister (R-K) equation. The application of these parametric models confirmed strong intermolecular interactions (The length (1.911 Å) and energy (HF value: −2237.54 kJ/mol and Des: −21.61 kJ/mol) of hydrogen bond) within the MEA + DETA binary mixed solutions. Spectroscopic analyses, including Raman and nuclear magnetic resonance hydrogen spectroscopy, revealed the presence of intermolecular hydrogen bonding (OH⋯N(H2)) in the MEA + DETA binary mixed solutions. Lastly, the CO2 absorption capacity of the solutions was experimentally studied, providing a theoretical foundation and reference data for future experiments and process design of CO2 capture.

Modification mechanism of green polyurethane modified asphalt prepared by in-situ polymerization

In order to investigate the modification mechanism of green polyurethane (PU) modified asphalt prepared by in-situ polymerization, PU was separated from PU modified asphalt (PUMA) and the molecular fragmentation information of synthesized PU and separated PU was characterized by pyrolysis-gas chromatography-mass spectrometry. The binding forms of the asphalt molecules to the PU were deduced, and the deduced structures were validated by infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, gel chromatography, elemental analysis, and molecular dynamics simulation. The results showed that compared to synthetic PU, the PU molecular fragments separated from modified asphalt additionally contained active asphalt components. Meanwhile, infrared and hydrogen spectra verified that the active components in the asphalt can chemically with -NCO in the PU prepolymer. The extension of curing time led to more combinations of asphalt molecules and PU prepolymers, which were manifested in the increases of the element contents of C, O, and S and the increase of molecular weight of PU separated from PUMA. The chain extender could not be completely reacted during the preparation and curing of PUMA and after curing for 6 months, the binding rate of PU prepolymer and chain extender was 24.80 %. PU prepolymer can react with the moisture in the air to generate amine group, and further generates urea group during the preparation and curing of PUMA. This work serves as a reference for the design and preparation of PUMA by in-situ polymerization.

Hydrophobic modification of biomass chitosan for treatment of oily wastewater and its demulsification mechanism

Traditional demulsifiers are commonly produced using raw materials like ethylene oxide and propylene oxide, which deplete significant petroleum resources and involve hazardous and complex manufacturing processes. In this investigation, a hydrophobically modified chitosan (HMC) was synthesized by grafting dodecyl diethanolamine onto natural chitosan to facilitate the separation of O/W emulsions. Characterization of HMC was conducted using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and scanning electron microscopy (SEM). The demulsification efficacy of HMC was assessed through a bottle test in an O/W emulsion containing 0.2 % crude oil. Results showed that at a HMC dosage of 40 mg/L, the light transmission (WT) and oil removal efficiency (WR) of the resulted water phase were 93.4 ± 0.8 % and 99.8 ± 0.1 %, respectively. Furthermore, the competitive adsorption between natural surfactants and HMC at the interface was investigated using interfacial tension (IFT), three-phase contact angle (CA), droplet coalescence time (CTA), and interfacial film substitution. A potential demulsifying mechanism was also proposed, emphasizing HMC’s hydrophilic core and dispersed hydrophobic alkyl chains that enable rapid diffusion to the oil–water interface, replacing interfacial active components to induce demulsification by destabilizing the composite film. The advantages of HMC demulsifier over commercial demulsifiers lie in its superior environmental benefits, diverse range of sources, higher efficiency, and outstanding demulsification performance.

Synthesis of suspension stabilizers for isolation fluids by response surface methodology and study of their properties

In order to solve the problem of unstable settling of isolation fluid at high temperatures, high-temperature-resistant suspension stabilizers for isolation fluids were prepared. Using the free radical aqueous solution method with 2-acrylamido-2-methylpropanesulfonic acid (AMPS), YX-1 (a monomer containing an amide group) as the main chain of the molecule, and N-Vinylpyrrolidone (NVP) and DX-2 (monomer containing hydrophobic groups) as the side chains of the molecule. We innovate the suspension stabilizer synthesis process, the synthesis conditions of the suspension stabilizer were optimized by using the one-factor experimental design and response surface analysis. The elemental composition and structure of the polymer suspension stabilizers were tested and analyzed by using X-ray spectroscopy (XPS), infrared spectroscopy (FTIR) and nuclear magnetic resonance hydrogen spectroscopy (H NMR). The hydrophobic aggregation behaviour of the polymer molecular chains was demonstrated from a microscopic point of view using fluorescence spectroscopy tests and size analysis of polymer molecular aggregates. Oscillation experiments on the isolation solution with suspension stabiliser showed that the hydrophobic groups contained in the polymers can undergo the effect of joining and bridging, and can also form a strong spatial network structure at 220°C, leading to the enhanced elasticity of the isolation fluid, which helps to alleviate the sedimentation of barite. Sedimentation stability and compatibility were evaluated for the isolation fluid containing suspension stabilizers. It was found that the isolation solution suspension performance is good under the condition of 90–220℃, its density difference is less than 0.10 g/cm3. It can also effectively prevent the contact contamination of the drilling fluid cement slurry, which is conducive to the improvement of the quality of the deep well cementing.

Improving the Solubility, Stability, and Bioavailability of Albendazole through Synthetic Salts.

Albendazole (ABZ) is a highly effective yet poorly water-soluble antiparasitic drug known to form salts (ABZ-FMA, ABZ-DTA, and ABZ-HCl) with fumaric acid (FMA), D-tartaric acid (DTA), and hydrochloric acid (HCl). This research utilized a range of analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), powder X-ray diffraction (PXRD), dynamic vapor sorption (DVS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), to validate and characterize the solid-state properties of these drug salts. This study also assessed the solubility and intrinsic dissolution rate (IDR) of these salts under different pH conditions compared to the active pharmaceutical ingredient (API) and conducted stability studies. Moreover, the in vivo pharmacokinetic performance of ABZ salt was evaluated. The results of this study reveal that the new solid form of ABZ is primarily associated with amino acid esters and benzimidazole groups, forming intermolecular interactions. All three ABZ salts significantly improved the solubility and dissolution rate of ABZ, with ABZ-HCl demonstrating the optimal performance. Importantly, the drug salt exhibited robust physical stability when exposed to adverse conditions, including strong light irradiation (4500 ± 500 lux), high humidity (92.5 ± 5% relative humidity), elevated temperatures (50 ± 2 °C), and accelerated test conditions (40 °C/75 ± 5% relative humidity). Lastly, the in vivo pharmacokinetic analysis demonstrated that ABZ salt led to a substantial increase in AUC(0-24) and Cmax compared to ABZ. This elevation in solubility in aqueous solvents signifies that ABZ salt exhibits characteristics that can enhance oral bioavailability and pharmacokinetics. These findings provide potential solutions for the development of more effective and innovative drug formulations.

Method for measuring the charge radii of charged hyperons from the time-like region

We propose a novel method for measuring the charge radii of charged stable hadrons, with which the first measurement of the charge radii of the Σ+ and the Ξ− is foreseen. The method explores the facts that the Dalitz decay ψ(2S)→YY¯e+e− contains the hyperon form factors and the lowest measurable four-momentum transfer squared can be as low as ∼4me2=1.05×10−6GeV2 in the time-like region. We identify a kinematic region where the hyperon form factors are essential and propose a method for subtracting the background from the data. It is estimated that the hyperon charge radii can be measured to a precision of about 0.2 fm with the BESIII experiment and one order of magnitude better at the future Super τ-Charm Facility. Moreover, the same method can be used to measure the charge radius of the proton, which provides an independent cross-check on the extraction of proton radius from elastic ep scattering or leptonic hydrogen spectroscopy.

Preparation of a low-temperature demulsifier derived from natural cottonseed oil

In this study, a low-temperature demulsifier (TEP-L) was synthesized by a simple method using polyethylene glycol 1000, and low-cost and readily accessible cottonseed oil as raw materials. The cottonseed oil was first hydrolyzed and then directly reacted with polyethylene glycol 1000 to obtain TEP-L. The chemical composition of TEP-L was determined by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance hydrogen spectroscopy (1H NMR). A comprehensive investigation was conducted to explore the demulsification performance of TEP-L in water-in-oil (W/O) emulsion. The investigation notably considered the effect of demulsifier dosage, temperature, settling time, pH value, and salinity on the demulsification process. The results demonstrated that the dehydration rate (DR) could reach 100 % with 1000 mg/L of TEP-L at 40 ℃ for 21 h, or a dosage of 500 mg/L at 60 ℃ for 240 min. Moreover, TEP-L exhibited a DR exceeding 90 % over a broad pH range of 8–12 and displayed remarkable resistance to salt. Characterization methods such as surface tension (SFT), dynamic interface tension (IFT), zeta potential, and optical microscopy observation were utilized to investigate the demulsification mechanisms.

Preparation of benzothiocyanine‐carboxymethyl cellulose composite film and its antimicrobial properties

AbstractCellulose has a wide range of uses. It could be modified to create cellulose‐based hydrophobic materials and cellulose‐based conductive and stable flexible films, but it did not have antibacterial properties and was susceptible to bacterial erosion. In order to improve the utilization of cellulose materials and broaden the application of cellulose materials, cellulose could be given certain antibacterial properties by combining it with antimicrobial agents. This study focused on creating an organic antimicrobial agent, Benzothiocyanine (TCMTB), from CH2ClBr, and then developing a TCMTB‐CMC composite antimicrobial film by combining TCMTB with CMC. The successful synthesis of TCMTB was confirmed through NMR hydrogen spectroscopy testing. By varying the proportions of TCMTB in CMC, three types of composite antimicrobial cellulose film were produced. The study also assessed the impact of TCMTB on the mechanical strength of CMC film and tested the antimicrobial effectiveness of the composite film using the plate counting method. Results showed that the composite film had high inhibition rates, with 96.2% against Escherichia coli and 98.6% against Staphylococcus aureus. To establish a theoretical foundation for its use in seed encapsulation, leather preservation, and other applications.

Photocurrent, electrochemical characteristic and photodegradation of two Ag20 cage isomers co-constructed by thiol and carboxylate/sulfonate and induced by CO32– template

Assembly of AgStBu and PhCOOH ligands with the assistance of soluble silver salt CH3COOAg/CF3SO3Ag in methanol, N, N-dimethylformamide (DMF) and dichloromethane solution, yielded two Ag20 cage isomers co-constructed by thiol and carboxylate/sulfonate ligands encapsulating a CO32– anion template, [(CO32–)@Ag20(StBu)10(PhCOO)4(CH3COO)4(DMF)4] (1) and [(CO32–)@Ag20(StBu)10(PhCOO)6(CF3SO3)2(DMF)4]·2DMF (2). The CO32– anion template was generated in situ by fixing atmospheric CO2. The precise structures of 1 and 2 were confirmed by single-crystal X-ray diffractometry (SCXRD). The thermal stability of compounds 1 and 2 was proved by thermogravimetric (TG) analysis, and their solution stability was characterized by nuclear magnetic resonance hydrogen spectroscopy (1H NMR). The absorption spectra, photocurrent responses, and luminescence of compounds 1 and 2 were investigated. In addition, the photodegradation of methylene blue (MB) and cyclic voltammetry characteristic curves of 1 and 2 were also studied.

Electromagnetic form factors of the nucleon from Nf=2+1 lattice QCD

There is a long-standing discrepancy between different measurements of the electric and magnetic radii of the proton. Lattice QCD calculations are a well-suited tool for theoretical investigations of the structure of the nucleon from first principles. However, all previous lattice studies of the proton’s electromagnetic radii have either neglected quark-disconnected contributions or were not extrapolated to the continuum and infinite-volume limit. Here, we present results for the electromagnetic form factors of the proton and neutron computed on the (2+1)-flavor coordinated lattice simulations (CLS) ensembles including both quark-connected and -disconnected contributions. From simultaneous fits to the Q2-, pion-mass, lattice-spacing, and finite-volume dependence of the form factors, we determine the electric and magnetic radii and the magnetic moments of the proton and neutron. For the proton, we obtain as our final values ⟨rE2⟩p=(0.672±0.014(stat)±0.018(syst)) fm2, ⟨rM2⟩p=(0.658±0.012(stat)±0.008(syst)) fm2, and μMp=(2.739±0.063(stat)±0.018(syst). The magnetic moment is in good agreement with the experimental value, as is the one of the neutron. On the one hand, our result for the electric (charge) radius of the proton clearly points towards a small value, as favored by muonic hydrogen spectroscopy and the recent ep-scattering experiment by PRad. Our estimate for the magnetic radius, on the other hand, is well compatible with that inferred from the A1 ep-scattering experiment. Published by the American Physical Society 2024