Electron-electron Interaction Research Articles

Ultrafine Ni-MoOx Nanoparticles Anchored on Nitrogen-Doped Carbon Nanosheets: A Highly Efficient Noble-Metal-Free Catalyst for Ammonia Borane Hydrolysis.

The development of low-cost and high-efficiency catalysts for the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3) is still a challenging technology. Herein, ultrafine MoOx-doped Ni nanoparticles (~3.0 nm) were anchored on g-C3N4@glucose-derived nitrogen-doped carbon nanosheets via a phosphate-mediated method. The strong adsorption of phosphate-mediated nitrogen-doped carbon nanosheets (PNCS) for metal ions is a key factor for the preparation of ultrasmall Ni nanoparticles (NPs). Notably, the alkaline environment formed by the reduction of metal ions removes the phosphate from the PNCS surface to generate P-free (P)NCS so that the phosphate does not participate in the subsequent catalytic reaction. The synthesized Ni-MoOx/(P)NCS catalysts exhibited outstanding catalytic properties for the hydrolysis of AB, with a high turnover frequency (TOF) value of up to 85.7 min-1, comparable to the most efficient noble-metal-free catalysts and commercial Pt/C catalyst ever reported for catalytic hydrogen production from AB hydrolysis. The superior performance of Ni-MoOx/(P)NCS can be ascribed to its well-dispersed ultrafine metal NPs, abundant surface basic sites, and electron-rich nickel species induced by strong electronic interactions between Ni-MoOx and (P)NCS. The strategy of combining multiple modification measures adopted in this study provides new insights into the development of economical and high-efficiency noble-metal-free catalysts for energy catalysis applications.

Post-modified linker functionalization of metal organic frameworks for high-efficiency adsorption and quantification of trace organophosphorus pesticides in environmental water

Water pollution caused by organophosphorus pesticides (OPPs) from agricultural production causes vital great threat to mankind lives and thus developing a method for rapid removal and detection of OPPs is urgent. In this work, we proposed the linker functionalization of metal organic frameworks (UiO-66) by post-modification to generate defects and active sites for tailoring their adsorption behavior. The metal organic frameworks (MOFs) modified by functional groups (amino and pyridine) exhibited similar physicochemical property and pore structure. The UiO-66-PA exhibited an excellent performance of rapid adsorption of OPPs in water with average capacity of 246.55 mg/g. Experimental characterizations and theoretical simulations revealed that the enhanced binding energy between UiO-66-PA and OPPs resulted from synergistic interaction between pyridine and OPPs via nucleophilic effect, π-π interaction, and metal electronic interaction, boosting the adsorption capacity and removal efficiency, which suggested that functional group plays important role in improving performance. When used it as adsorbent for analysis of OPPs in water coupled with ambient ionization source, UiO-66-PA exhibited an excellent performance of the quantitative detection of OPPs in water with limit of detections (LODs) of 0.076–––0.251 ng/mL and relative standard deviations (RSDs) of 1.13 % − 5.84 %. In addition, the proposed analytical method could be applied in analysis of three environmental water samples with great sensitivity, anti-interference and reusability, which demonstrated that UiO-66-PA afforded outstanding selectivity for OPPs and could be appropriate for high-throughput screening and on-site analysis. This work could provide a novel method to design MOFs-based adsorbents with functions of removal and purification via post-modification and exhibit a great potential to rapid analysis of OPPs in environmental water.

S-doped NiCo layered double hydroxides enable efficient and durable methanol oxidation and oxygen reduction reactions for Zn-methanol-air batteries

The employment of alcohol oxidation reactions (AORs) is thermodynamically more favorable to replace the anodic oxygen evolution reaction (OER) in rechargeable Zn-air batteries (ZABs). As a representative AOR-coupled ZAB, Zn-methanol-air battery (ZMAB) gratifyingly delivers a lower charge voltage, higher energy efficiency, longer cycle life and more valuable charge product in comparison with the traditional ZAB. For such emerging ZMABs, it is imperative to explore efficient, stable and cost-effective bifunctional electrocatalysts for both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). Herein, sulfur-doped NiCo layered double hydroxides (termed NiCo-LDH@SOH) are fabricated by a room-temperature surface sulfurization route. Remarkably, the NiCo-LDH@SOH heterostructure catalyst achieves a superb bifunctional activity for MOR and ORR, performing a low potential gap ΔE between the Ej10 for MOR and the half-wave potential E1/2 for ORR of only 0.596 V, far surpassing that (0.790 V) for Pt/C-IrO2 benchmark catalyst. The electronic interactions between S2− and transition metal ions significantly accelerate the charge transfer process and generate highly efficient Ni3+ and Co2+ active sites on NiCo-LDH@SOH, which account for the exceptional MOR and ORR performance, respectively. Thanks to the favorable replacement of OER with MOR and the excellent MOR/ORR bifunctional activity of NiCo-LDH@SOH, the ZMAB can output a comparable discharge power density (140 mW cm−2) to the traditional ZAB counterpart (149 mW cm−2), but a much lower charge voltage than the latter. In consequence, the ZMAB demonstrates an extraordinary long-term cyclability of 2880 cycles for 480 h (20 days) with almost no degradation, which is more than 5 times longer than that of the traditional ZAB.

Electronic metal-support interactions for defect-induced Ru/Co-Sm2O3 mesosphere to achieve efficient NaBH4 hydrolysis activity

Crafting resilient catalysts that promote H2 production through the hydrolysis of hydrogen storage materials like sodium borohydride stands paramount for the impending hydrogen economy. In this study, we propose a versatile metal–organic framework (MOF)-assisted approach to systematically explore the impact of electron-metal support interaction (EMSI) of Ru-modified Co-Sm2O3 (Ru/Co-Sm2O3) on H2 evolution from NaBH4 hydrolysis. Strategic annealing at 800 °C induces cobalt vacancies on the Ru/Co-Sm2O3 surface, optimizing the exposure of active sites and amplifying mass-charge transfer efficiency. Consequently, the defect-enriched Ru/Co-Sm2O3 showcases an impressive hydrogen generation rate (HGR = 0.430 mol min−1 gcatalyst−1) and outstanding cycling resilience, eclipsing the performance of most contemporary catalysts. Experimental findings reveal that Sm can not only adjust the Ru lattice spacing to accommodate more BH4−, but also modulate the Co vacancy concentration, thus bolstering the charge transport and ameliorating the catalyst's electrical conductivity. DFT calculations confirm that the Michaelis-Menten/Eley-Rideal mechanism is more appropriate to explain the hydrolysis of NaBH4.

Highly-dispersed 2D NiFeP/CoP heterojunction trifunctional catalyst for efficient electrolysis of water and urea

The electrocatalytic production of “green hydrogen”, such as through the electrolysis of water or urea has been vigorously advocated to alleviate the energy crisis. However, their electrode reactions including oxygen evolution reaction (OER), urea oxidation reaction (UOR), and hydrogen evolution reaction (HER) all suffer from sluggish kinetics, which urgently need catalysts to accelerate the processes. Herein, we design and prepare an OER/UOR/HER trifunctional catalyst by transforming the homemade CoO nanorod into a two-dimensional (2D) ultrathin heterojunction nickel–iron-cobalt hybrid phosphides nanosheet (NiFeP/CoP) via a hydrothermal-phosphorization method. Consequently, a strong electronic interaction was found among the Ni2P/FeP4/CoP heterogeneous interfaces, which regulates the electronic structure. Besides the high mass transfer property of 2D nanosheet, Ni2P/FeP4/CoP displays improved OER/UOR/HER performance. At 10 mA cm−2, the OER overpotential reaches 274 mV in 1.0 M KOH, and the potential of UOR is only 1.389 V in 1.0 M KOH and 0.33 M urea. More strikingly, the two-electrode systems for electrolysis water and urea-assisted electrolysis water assembled by NiFeP/CoP could maintain long-term stability for 35 h and 12 h, respectively. This work may help to pave the way for upcoming research horizons of multifunctional electrocatalysts.

Island-in-Sea Structured Pt3Fe Nanoparticles-in-Fe Single Atoms Loaded in Carbon Materials as Superior Electrocatalysts toward Alkaline HER and Acidic ORR.

In this work, Pt3Fe nanoparticles (Pt3Fe NPs) with the ordered internal structure and Pt-rich shells surrounded by plenty of Fe single atoms (Fe SAs) as active species (Pt3Fe NP-in-Fe SA) loaded in the carbon materials are successfully fabricated, which are abbreviated as island-in-sea structured (IISS) Pt3Fe NP-in-Fe SA catalysts. Moreover, the synergistic effect of O-bridging between Pt3Fe NPs and Fe SAs, and the ordered internal structured Pt3Fe NPs with Pt-rich shells of an optimal thickness contributes to the achievement of the local acidic environments on the surfaces of Pt3Fe NPs in the alkaline hydrogen evolution reaction (HER) and the enhancement of the desorption rate of *OH intermediate in the acidic oxygen reduction reaction (ORR). In addition, the electronic interactions between Pt3Fe NPs and dispersed Fe SAs cannot only provide efficient electrons transfer, but also prevent the aggregation and dissolution of Pt3Fe NPs. Furthermore, the overpotential and the half wave potential of the as-prepared IISS Pt3Fe NP-in-Fe SA catalysts toward the alkaline HER and toward the acidic ORR are 8mV at a current density of 10mAcm-2 and 0.933V, respectively, which is 29 lower and 86mV higher than those (37mV and 0.847V) of commercial Pt/C catalysts.

Computational insight into the spectroscopic and molecular docking analysis of estrogen receptor with ligand 2,3-dimethyl-N[2-(hydroxy)benzylidene] aniline

A comprehensive approach encompassing a blend of spectral techniques and Density Functional Theory (DFT) was employed to elucidate the electronic, vibrational, structural, and nonlinear optical properties of 2,3-dimethyl-N[2-(Hydroxy)benzylidene] aniline (DNHBA). The investigation of this chemical compound involved a meticulous examination using spectroscopic techniques (FTIR, FT-Raman). The DFT calculations utilized the B3LYP method in conjunction with 6-311G (d, p) basis sets. The findings were substantiated by comparing the estimated vibrational frequencies and molecule geometry with experimental data. Using the Time Dependent −Density Functional Theory (TD-DFT) method to calculate the energy band gap of the compound at different solvents. We looked into frontier molecular orbitals (FMO) Molecular electrostatic potential (MEP) and natural bond analysis (NBO) to determine the compound’s kinetic stability and chemical reactivity. Hirshfeld surface (HS) analysis calculated the O–H..O, H-H and intermolecular interaction energy of the compound. The electron density distribution, interactions, and excitation within the title molecule are illustrated by performing topological analyses (RDG, ELF and LOL) using the Multiwfn software. In addition to these assessments, molecular dynamics provides an understanding of the system's dynamic development over a predefined duration during which atoms and molecules are permitted to interact. Utilizing the molecular docking approach allows us to energize the atomic-level interplay between small molecules and proteins within the binding sites of target proteins. This approach enhances our comprehension of vital biochemical processes associated with the behavior of small molecule. The intricacy and hazards associated with drug discovery and development processes have increased dramatically, leading to higher drug research costs.

SHORYUKEN: An open-source software package for calculating nonlocal exchange interactions in nanowires

We present the open-source software package, SHORYUKEN (Streamlined High-level Operations in Real-space to Yield, Understand, and Keep Exchange in Nanowires), for calculating nonlocal exchange interactions in nanowires with arbitrary geometries, sizes, doping densities, and compositions. In addition to enabling new calculations of nonlocal exchange, the SHORYUKEN software package is a significant enhancement of our previous HADOKEN code and includes new algorithmic improvements as well as an improved treatment of surface states for nanowires with intrinsic polarization. Our calculations show that the inclusion of nonlocal exchange can have significant effects on the eigenenergy spectrum, number of occupied states, and distribution of electrons within these nanosystems. The SHORYUKEN software package is the first open-source code for calculating nonlocal exchange to predict electron gas formation in nanowire systems with arbitrary cross-sectional geometries. Program summaryProgram Title: SHORYUKENCPC Library link to program files:https://doi.org/10.17632/f77p84pbcv.1Licensing provisions: GNU General Public License 3Programming language: MATLABNature of problem: The SHORYUKEN code calculates nonlocal exchange interactions of electrons in nanowires by solving modified nonlocal exchange and Poisson-like equations self-consistently on a finite element grid. The software package is capable of performing calculations for core-multishell nanowires with arbitrary cross-sectional shapes.Solution method: iterative solution of the Schrödinger-Poisson equations with nonlocal exchange using finite element methods and sparse matrix linear algebra

Regulating lattice tensile strain of Ru-Co bimetallic nanoparticles on carbonized wood for boosting its hydrogen evolution reaction

The development of high-performance catalysts for hydrogen production originating from water electrolysis at the cathode is very crucial, but still a challenge. Here, trace Ru-doped Co bimetallic nanoparticles (named RuxCoy/CW-z, x/y and z represent the molar ratio and total molar content of metals) were in situ decorated on carbonized wood by the vacuum impregnation and high-temperature annealing method. Ru1Co10/CW-2 demonstrates good hydrogen evolution reaction (HER) intrinsic activity with the overpotential of −42 mV (at −10 mA/cm−2) and Tafel slope of 75 mV dec−1 in a 1.0 M KOH, indicating its favorable HER reaction kinetics, and Ru1Co10/CW-2 exhibits good stability for 100 h (at −50 mA/cm−2). The good performances of Ru1Co10/CW-2 can be ascribed to the adjustable lattice tensile strain and electronic interactions, while the porous carbonized wood promotes electron transfer, electrolyte transport and gas escape. This work combines the advantages of lattice tensile strain with self-supported porous carbonized wood for HER in alkaline solution, which provides a valuable reference for synthesizing carbonized wood electrode materials with very low Ru content.

Robust pseudocapacitive Na+ intercalation induced by MoS2 on active Mo2C current collector interface for high areal capacity sodium-ion batteries

Sodium-ion batteries (SIBs) have emerged as compelling alternatives in the realm of electrochemical energy devices, poised to substitute lithium-ion batteries (LIBs). The primary challenge encompasses not only the scarcity of anode materials exhibiting exceptional Na+ storage capacity but also the endeavor to achieve high areal capacity. To address this challenge, a comprehensive strategy is proposed that entails utilizing a highly conductive molybdenum dicarbide (Mo2C) current collector (denoted as CCM) as a supporting scaffold for the bottom-up growth of molybdenum disulfide nanosheets (MoS2, serving as the main active component) (denoted as CCM@MoS2). The CCM improves interfacial bonding with MoS2 nanosheets and offers additional capacity to accommodate the increased Na+ insertion activity. Both theoretical and kinetic analyses reveal that the enhanced Na+ storage properties primarily stem from favorable adsorption energy, reduced diffusion barrier, and intercalation pseudocapacitance due to the strong electronic interfacial interaction between active CCM and MoS2. Hence, the as-prepared optimized CCM@MoS2 electrode exhibits a superior areal capacity of 6.36 mAh cm−2 at 0.4 mA cm−2, excellent rate capability of 1.02 mAh cm−2 at 24 mA cm−2 and long cycle life up to 500 cycles at 4 mA cm−2. Interesting, our as-prepared CCM@MoS2 electrode shows better performance for Na+ storage than Li+ storage at higher current density, affirming the enhanced kinetics in our architecture. This work proposes a rational strategy to enhance the areal capacity and stability of MoS2-based anode for SIBs and beyond.

Computing the gamma-ray, charged particles and fast neutron-shielding performances of selected alloys

Gamma-ray, charged particles and neutron-shielding properties of ternary alloy materials, (97.3 – x) Pb – x Cd – 2.7Ag (x = 10, 18 and 30) have been theoretically investigated. First, the effectiveness of gamma-ray shielding for the alloys was studied by using the Phy-X/PSD programme. Mass and linear attenuation coefficients (MAC and LAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), effective atomic numbers (Zeff), effective electron densities (Neff) and effective conductivity (Ceff) were calculated for photon energy range 0.015–15 MeV. Second, the mass stopping powers (MSPs; dE/ρdx; MeVcm2/g) and ranges for electron, proton and alpha particle interactions were calculated at energy 0.01–20 MeV. Finally, the removal cross-section of fast neutron (FNRCS) for the alloys was calculated by the partial density method. Moreover, the neutrons and gamma-rays shielding effectiveness of ternary alloys were investigated using Monte Carlo (MCNP4b). The MCNP4b calculations were performed for neutrons in the energies 4 and 4.5 MeV. While the shielding parameters of gamma rays were done in the energy range of 0.015–15 MeV. The obtained results of radiation shielding showed that the P1 sample owns a good shielding effectiveness against neutrons and gamma rays compared to previously published studies. The comparison of the computed values has revealed a reasonable agreement between Phy-X/PSD and MCNP4b. This study gives essential data for potential applications of these materials in nuclear reactor core design and other industries for the evaluation of effective ionising radiation shielding materials.

Rational modulation of redox equilibrium over Mn modified Ce-Sn catalyst for low-temperature elimination of NO and Hg0

The synergistic catalytic removal of NO and Hg0 under low temperatures is still a great challenge. Here, we report a Mn-modified Ce-Sn catalyst for simultaneous removal of NO and Hg0 at low temperature. The optimum Mn0.2/Ce0.33Sn0.67 exhibited more than 95 % NO conversion and N2 selectivity above 86 % at 150–250 ℃ as well as Hg0 removal of nearly 100 % within 150–300 ℃. SnO2-promoted Ce-Sn solid solution enhanced the surface proportion of Ce3+, the number of surface chemisorbed oxygen and the electronic interaction within Ce-Sn linkage. Mn modification further reasonably promoted redox cycling at low temperatures and improved acidic distribution of catalyst. Under the cooperation of Ce-Sn and Mn sites, the presence of Hg0 could substantially facilitate the reduction of NO at 250–300 ℃ and the SCR atmosphere had a weak inhibitory effect on Hg0 removal. During the SCR process, the NH4+ and NH2 species that directly reacted with gaseous NO following the Eley − Rideal mechanism and the improved reactivity of NH2 with nitrates following the Langmuir − Hinshelwood mechanism enhanced the NO conversion efficiency at low temperature. Meanwhile, Mn modification could alleviate competitive adsorption of NH3 on Hg0 and promote the formation of more chemically adsorbed mercury species. This work will provide guidance for the design of low-temperature catalysts for the simultaneous removal of NO and Hg0 in flue gas.

Unveiling intermolecular mechanism and electronic properties between asphaltene and deep eutectic solvent for enhanced oil recovery using first principles calculation

Electronic structure and interaction energy calculations offer critical insights into non-bonded interactions in solute–solvent systems that can be used to extract heavy oil, particularly asphaltene, in enhanced oil recovery. The present study examines deep eutectic solvent (DES) interaction with asphaltene through first-principles calculations, revealing the role of hydrogen bonds, overall system stability, and its mechanism. The analysis reveals that the inclusion of asphaltene makes the DES-asphaltene structure less stable, i.e., increasing wettability with DES. DES formed non-bonded interactions with asphaltene's aliphatic segments but excluded aromatic rings due to strong π-π interactions. Among the studied DESs, DES1 (choline chloride and urea, 1:2 ratio) exhibited a strong interaction with asphaltene (-103.946 kJ/mol) and formed a hydrogen bond. All systems show negative binding energies, which indicate stability. Notably among them, DES2 (choline chloride and thiourea, 1:2) and DES3 (choline chloride and ethylene glycol, 1:2) displayed remarkable stability with asphaltene, evident in a widened band gap of 2.182 and 2.157 eV, respectively.

Anisotropic metal–insulator transition in strained VO2(B) single crystal

Mechanical strain can induce noteworthy structural and electronic changes in vanadium dioxide, imparting substantial scientific importance to both the exploration of phase transitions and the development of potential technological applications. Unlike the traditional rutile (R) phase, bronze-phase vanadium dioxide [VO2(B)] exhibits an in-plane anisotropic structure. When subjected to stretching along distinct crystallographic axes, VO2(B) may further manifest the axial dependence in lattice–electron interactions, which is beneficial for gaining insights into the anisotropy of electronic transport. Here, we report an anisotropic room-temperature metal–insulator transition in single-crystal VO2(B) by applying in-situ uniaxial tensile strain. This material exhibits significantly different electromechanical responses along two anisotropic axes. We reveal that such an anisotropic electromechanical response mainly arises from the preferential arrangement of a strain-induced unidirectional stripe state in the conductive channel. This insulating stripe state could be attributed to the in-plane dimerization within the distorted zigzag chains of vanadium atoms, evidenced by strain-modulated Raman spectra. Our work may open up a promising avenue for exploiting the anisotropy of metal–insulator transition in vanadium dioxide for potential technological applications.

Possible charge ordering and anomalous transport in graphene/graphene quantum dot heterostructure

Observations of superconductivity and charge density waves (CDW) in graphene have been elusive thus far due to weak electron–phonon coupling (EPC) interactions. Here, we report a unique observation of anomalous transport and multiple charge ordering phases at high temperatures ( T1∼213K , T2∼325K ) in a 0D−2D van der Waals (vdW) heterostructure comprising of single layer graphene (SLG) and functionalized (amine) graphene quantum dots (GQD). The presence of functionalized GQD contributed to charge transfer with shifting of the Dirac point ∼ 0.05 eV above the Fermi level (ab initio simulations) and carrier density n∼−0.3×1012 cm−2 confirming p-doping in SLG and two-fold increase in EPC interaction was achieved. Moreover, we elucidate the interplay between electron–electron and electron–phonon interactions to substantiate high temperature EPC driven charge ordering in the heterostructure through analyses of magnetotransport and weak anti-localization (WAL) framework. Our results provide impetus to investigate strongly correlated phenomena such as CDW and superconducting phase transitions in novel graphene based heterostructures.

Optical Microcavity‐Induced Moiré Exciton Localization in Twisted WSe2 Homobilayer

Abstract2D moiré superlattices offer a versatile platform for manipulating quantum materials, exploiting their spatially varying atomic registry to modify electronic structures, resulting in the emergence of flat electronic minibands, enhanced electronic interactions, and the onset of novel quantum phenomena. Despite extensive investigations into moiré excitons within twisted bilayer moiré superlattices, the interplay between moiré superlattices and optical microcavities remains elusive. Here, a WSe2 homobilayer with a small twist angle positioned on optical microcavities atop a SiO2 (285 nm)/Si substrate is investigated. Utilizing low‐temperature photoluminescence (PL) spectroscopy, it is observed that the twisted homobilayer at the edge of the optical cavity (Edge‐THB) exhibits enhanced localization of moiré excitons and a deeper moiré potential. This behavior is attributed to the combined influence of strain induced by the optical microcavity structure on the moiré superlattice and the amplification of the electromagnetic field. Furthermore, the existence of moiré excitons through a comprehensive analysis, encompassing temperature‐dependent PL spectra, circularly polarized PL spectra, and Landé g‐factor measurements for Edge‐THB is validated. These findings provide valuable insights into the intricate interaction between moiré superlattices and optical microcavities, paving the way for future applications in quantum technologies.

Janus electronic state of supported iridium nanoclusters for sustainable alkaline water electrolysis

Metal-support electronic interactions play crucial roles in triggering the hydrogen spillover (HSo) to boost hydrogen evolution reaction (HER). It requires the supported metal of electron-rich state to facilitate the proton adsorption/spillover. However, this electron-rich metal state contradicts the traditional metal→support electron transfer protocol and is not compatible with the electron-donating oxygen evolution reaction (OER), especially in proton-poor alkaline conditions. Here we profile an Ir/NiPS3 support structure to study the Ir electronic states and performances in HSo/OER-integrated alkaline water electrolysis. The supported Ir is evidenced with Janus electron-rich and electron-poor states at the tip and interface regions to respectively facilitate the HSo and OER processes. Resultantly, the water electrolysis (WE) is efficiently implemented with 1.51 V at 10 mA cm–2 for 1000 h in 1 M KOH and 1.44 V in urea-KOH electrolyte. This research clarifies the Janus electronic state as fundamental in rationalizing efficient metal-support WE catalysts.

DC electrical conductivity measurements of warm dense matter using ultrafast THz radiation

We describe measurements of the DC electrical conductivity of warm dense matter using ultrafast terahertz (THz) pulses. THz fields are sufficiently slowly varying that they behave like DC fields on the timescale of electron–electron and electron–ion interactions and hence probe DC-like responses. Using a novel single-shot electro-optic sampling technique, the electrical conductivity of the laser-generated warm dense matter was determined with <1 ps temporal resolution. We present the details of the single-shot THz detection methodology as well as considerations for warm dense matter experiments. We, then, provide proof-of-concept studies on aluminum driven to the warm dense matter regime through isochoric heating and shock compression. Our results indicate a decrease in the conductivity when driven to warm dense matter conditions and provide a platform for future warm dense matter studies.

Resonant Interactions Between Relativistic Electrons and EMIC Waves Modified by Partial Shell Proton Velocity Distributions

AbstractResonant interactions of relativistic electrons with electromagnetic ion cyclotron (EMIC) waves were previously considered under the cold plasma approximation or in hot plasmas with bi‐Maxwellian distributions. Here, we examine their resonant interactions in hot plasmas with partial shell distributions and find that such distributions can significantly alter the dispersion relation of EMIC waves and thus the corresponding wave‐induced electron pitch angle scattering rates and loss timescales compared to those under the cold plasma assumption. Regardless of wave band and frequency, partial shell distributed hot protons tend to uplift the electron minimum resonant energy, and reduce (raise) the pitch angle scattering rates of electrons at low (high) energies and large (small) pitch angles. Correspondingly, the loss timescales lengthen for low‐energy electrons but shorten for high‐energy electrons. Such tendencies are generally more significant for lower‐frequency EMIC waves and larger shell temperature, anisotropic degree, and concentration.

The Astrochemistry Low-energy Electron Cross-Section (ALeCS) database

Context. Electron–molecule interaction is a fundamental process in radiation-driven chemistry in space, from the interstellar medium to comets. Therefore, knowledge of interaction cross sections is key. There have been a plethora of both theoretical and experimental studies of total ionization cross sections spanning from diatomics to complex organics. However, the data are often spread over many sources or are not public or readily available. Aims. We introduce the Astrochemistry Low-energy Electron cross-section (ALeCS) database. This is a public database for electron interaction cross sections and ionization rates for molecules of astrochemical interest. In particular, we present here the first data release, comprising total ionization cross sections and ionization rates for over 200 neutral molecules. Methods. We include optimized geometries and molecular orbital energies at various levels of quantum chemistry theory. Furthermore, for a subset of the molecules, we have calculated ionization potentials. We computed the total ionization cross sections using the binary-encounter Bethe model and screening-corrected additivity rule, and we computed ionization rates and reaction network coefficients for molecular cloud environments. Results. We present the cross sections and reaction rates for >200 neutral molecules ranging from diatomics to complex organics, with the largest being C14H10. We find that the screening-corrected additivity rule cross sections generally significantly overestimate experimental total ionization cross sections. We demonstrate that our binary-encounter Bethe cross sections agree well with experimental data. We show that the ionization rates scale roughly linearly with the number of constituent atoms in the molecule. Conclusions. We introduce and describe the public ALeCS database. For the initial release, we include total ionization cross sections for >200 neutral molecules and several cations and anions calculated with different levels of quantum chemistry theory, the chemical reaction rates for the ionization, and network files in the formats of the two most popular astrochemical networks: the Kinetic Database for Astrochemistry, and UMIST. The database will be continuously updated for more molecules and interactions.