Isotope Separation Research Articles

Production and purification of molecular 225Ac at CERN-ISOLDE

AbstractThe radioactive nuclide 225Ac is one of the few promising candidates for cancer treatment by targeted-$$\alpha$$ α -therapy, but worldwide production of 225Ac faces significant limitations. In this work, the Isotope Separation On-Line method was used to produce actinium by irradiating targets made of uranium carbide and thorium carbide with 1.4-GeV protons. Actinium fluoride molecules were formed, ionized through electron impact, then extracted and mass-separated as a beam of molecular ions. The composition of the mass-selected ion beam was verified using time-of-flight mass spectrometry, $$\alpha$$ α - and $$\gamma$$ γ -ray decay spectrometry. Extracted quantities of $$^{225}\textrm{Ac}^{19}\textrm{F}_2^{+}$$ 225 Ac 19 F 2 + particles per $$\upmu$$ μ C of incident protons were $$3.9(3)\times 10^7$$ 3.9 ( 3 ) × 10 7 from a uranium carbide target and $$4.3(4)\times 10^7$$ 4.3 ( 4 ) × 10 7 for a thorium carbide target. Using a magnetic mass separator, the long-lived contamination 227 Ac is suppressed to $$<5.47\times 10^{-7}$$ < 5.47 × 10 - 7 (95% confidence interval) with respect to 225Ac by activity. Measured rates scale to collections of 108 kBq$$\upmu$$ μ A$$^{-1}$$ - 1 h$$^{-1}$$ - 1 of directly produced $$^{225}\textrm{Ac}^{19}\textrm{F}_2^{+}$$ 225 Ac 19 F 2 + .

Optimization of Liquid Phase Catalytic Exchange Process for Hydrogen Isotope Separation Using Orthogonal Experiment Design

Optimization of Liquid Phase Catalytic Exchange Process for Hydrogen Isotope Separation Using Orthogonal Experiment Design

Stable isotopic evidence for increased terrestrial productivity through geological time

Marine life on Earth is known back to the Archean Eon, when life on land is assumed to have been less pervasive than now. Precambrian life on land can now be tested with stable isotopes because living soil CO2 is isotopically distinct for both carbon and oxygen from both marine and volcanic CO2. Our novel compilation of previously published oxygen and carbon isotopic compositions of pedogenic and paleokarst carbonate can be compared with the coeval marine record. Long-term enrichment (to heavier isotopic composition) of oxygen, but no significant trend in carbon through time, long apparent from marine carbonate, is now demonstrated also for pedogenic and paleokarst carbonate. Oxygen isotopic enrichment is not due to changing global temperature or hypsometry, but to increased evapotranspiration and photosynthesis on larger continents. Differences in isotopic composition between land and sea have increased in an episodic fashion, peaking at times of major evolutionary innovations for life on land, and also at times of ice ages. The δ13C and δ18O divergences between land and sea correspond to terrestrial productivity spikes including evolution of Neoproterozoic (635 Ma) lichens, middle Ordovician (470 Ma) non-vascular land plants, middle Devonian (385 Ma) forests, early Cretaceous (125 Ma) angiosperms, and middle Miocene (20 Ma) sod grasslands.

The Throttle Effect in Metal-Organic Frameworks for Distinguishing Water Isotopes.

Metal-organic frameworks (MOFs) have been widely used for separation, but amplifying subtle differences between similar molecules to achieve effective separation remains a great challenge. In this study, we utilize the fluorescent molecule uranine (Ura) to modulate the pores of zeolitic-imidazolate framework 8 (ZIF8), creating an unusual throttle effect. By monitoring fluorescence intensity changes in Ura, the transport diffusion process could be quantified to reveal the diffusion constant of solvents. When we pushed the Ura occupancy to its limit (from 59% to 76% and 98%), the diffusion rate decreases by 2 orders of magnitude. Most importantly, there is a significant dissymmetry between the two-way exchange rates of solvents, and the rates of H2O and D2O became distinguishable. Such unusual throttle effects disappear at low Ura occupancy of 59% and 76%. We believe that the throttle effect with small-molecule loading could provide a universal design principle for MOF-based applications, especially for isotope separation.

Thermal conductivity of WC: Microstructural design driven by first-principles simulations

The relationships between the microstructure and the thermal conductivity of binderless WC have been quantified, considering crystal orientation, isotopic abundance, porosity, and grain size. A significantly higher conductivity is predicted in the out-of-plane (c-axis) direction vs. the in-plane (a-axis) direction, using first principles simulations. Isotopic enrichment of the tungsten sublattice is predicted to increase conductivity, e.g., by a factor of 4–5 in the absence of boundary scattering. The results suggest that for an isotopically pure single crystal a thermal conductivity exceeding 1000 W m−1 K−1 may be achievable normal to the basal plane. The conductivity of samples with various porosities could be well fit by a minimum surface area (exponential) model, with a porosity exponent of b = 4.4. Experiment and simulation show a strong grain size dependence to conductivity below 1 µm, with a saturation beyond ∼10 µm. The experimental plateau values for κ were ∼45 % lower than those of the simulations due to deviations from perfect stoichiometry. We also find a higher scattering coefficient in the experiments, likely due to effects of grain size distribution and elongation. Our study clarifies the physical origin of disagreeing literature reports as being predominantly due to grain boundary scattering and enables microstructural design for thermally demanding environments.

Predicting Behavior and Fate of Atmospheric Mercury in Soils: Age-Dating METAALICUS Hg Isotope Spikes with Fallout Radionuclide Chronometry.

Soils accumulate anthropogenic mercury (Hg) from atmospheric deposition to terrestrial ecosystems. However, possible reemission of gaseous elemental mercury (GEM) back to the atmosphere as well as downward migration of Hg with soil leachate influence soil sequestration of Hg in ways not sufficiently understood in global biogeochemical models. Here, we apply fallout radionuclide (FRN) chronometry to understand soil Hg dynamics by revisiting the METAALICUS experiments 20 years after enriched isotope tracers (198Hg, 200Hg, 201Hg, and 202Hg) were applied to two boreal watersheds in northwestern Ontario, Canada. Hg spikes formed well-defined peaks in organic horizons of both watersheds at depths of 3-6 cm and were accurately dated to the year of spike application in 6 of 7 cases (error = -0.8 ± 1.2 years). A seventh site was depleted by ca. 90% of both the 200Hg spike and background Hg, and the spike was dated 16 years older than its application. Robust FRN age models and mass balances demonstrate that loss of Hg is attributable to its specific physicochemical behavior at this site, but more work is required to attribute this to reemission or leaching. This study demonstrates the potential of FRN chronometry to provide insights into Hg accumulation, mobilization, and fate in forest soils.

Interaction regimes of surface water and groundwater in a hyper-arid endorheic watershed on Tibetan Plateau: Insights from multi-proxy data

The interaction between surface water and groundwater is crucial for the management of water resources and the preservation of ecosystems within arid basins, but knowledge on their interaction regimes at the watershed scale remains relatively limited. The present research synthesizes a range of multi-proxy data, including satellite thermal infrared remote sensing, water piezometric level, hydrochemical analyses, and isotopic signatures (2H, 18O and 222Rn), to elucidate the interaction dynamics and patterns between surface water and groundwater within a representative hyper-arid closed basin on Tibetan Plateau. The findings indicate that the water in the basin originates primarily from the glacier/snow melt water and precipitation in the mountainous regions, and would experience multiple but spatially heterogeneous interactions between river and aquifers from the mountain pass to the tail salt lakes after entering the basin. Water interaction in the piedmont alluvial plain is dominated by the pattern of river seepage into aquifers with a water flux of 25.82 m3/s, which drives the development of hierarchical groundwater flow systems in the basin. The interaction pattern converts to groundwater discharge of the local groundwater flow system at the front of alluvial fan plain, which forms the principal spring-fed rivers and the predominant overflow zone in the basin with the groundwater discharge flux of 3.22 m3/s. Most of these discharged groundwaters would infiltrate back into the aquifers in the middle-upper part of the loess plain with the river water leakage flux of 2.89 m3/s. River water and phreatic groundwater present a gradual enrichment of hydrochemcial components and water stable isotopes (2H and 18O) along the flow path due to the intense evaporation in the loess plain. The multiple water interactions between surface water and groundwater lead to the anomalous distribution of fresh water in the middle-lower stream area, which is related to the intermediate groundwater flow system and the local variable groundwater flow system. Water interaction in the lowest salt-marsh plain is in the pattern of regional groundwater flow system discharge into the tail salt lakes under natural condition, but evolves to only discharge into the artificial brine extraction canals rather than the tail salt lakes after decades of brine exploitation. Our findings provide a conceptual and preliminarily quantificational understanding of the interaction regimes between surface water and groundwater in large arid closed basins at the watershed scale.

Separation of radioactive isotope 227Ac from LaBr3 via vacuum evaporation for low-background scintillating detectors

Both radioactive isotopes 138La and 227Ac in LaBr3:Ce crystal typically produce considerable intrinsic background signals, and thus hinder their applications with low count rates. Since the complete separation of 138La is almost impossible, the contamination of 138La is stubbornly present in all La-halide based scintillators. In this study, an efficient purification protocol based on vacuum distillation was developed to separate 227Ac from feedstock and reduce intrinsic background signal at 1.6–3 MeV introduced by 227Ac in LaBr3:Ce crystals. Through combined theoretical and experimental analysis, the alpha contamination from 227Ac in LaBr3: Ce was reduced exploiting the different evaporation behaviors of LaBr3 and AcBr3. Additional impurities were also reduced to lower levels, as confirmed by glow discharge mass spectrometry (GDMS). The purified material, distilled at various temperatures (1203 K, 1253 K, and 1303 K), was used to grow LaBr3:Ce single crystals for performance evaluation. The crystals distilled at 1203 K demonstrated enhanced scintillation performance, featuring lower background counts (0.0181 counts·s−1·cm−3 @1.6–3 MeV) by approximately 50%–60 % of untreated sample and excellent energy resolution (2.47 %@662 KeV). This study presents an effective approach for preparing low-background lanthanum bromide, so as to offer valuable insights for isotope separation in scintillation crystals by vacuum distillation.

Sustainable production of radionuclidically pure antimony-119

BackgroundRadiopharmaceutical therapy (RPT) uses radionuclides that decay via one of three therapeutically relevant decay modes (alpha, beta, and internal conversion (IC) / Auger electron (AE) emission) to deliver short range, highly damaging radiation inside of diseased cells, maintaining localized dose distribution and sparing healthy cells. Antimony-119 (119Sb, t1/2 = 38.19 h, EC = 100%) is one such IC/AE emitting radionuclide, previously limited to in silico computational investigation due to barriers in production, chemical separation, and chelation. A theranostic (therapeutic/diagnostic) pair can be formed with 119Sb’s radioisotopic imaging analogue 117Sb (t1/2 = 2.80 h, Eγ = 158.6 keV, Iγ = 85.9%, β+ = 262.4 keV, Iβ+ = 1.81%).ResultsWithin, we report techniques for sustainable and cost-effective production of pre-clinical quality and quantity, radionuclidically pure 119Sb and 117Sb, novel low energy photon measurement techniques for 119Sb activity determination, and physical yields for various tin target isotopic enrichments and thicknesses using (p, n) and (d, n) nuclear reactions. Additionally, we present a two-column separation providing a radioantimony yield of 73.1% ± 6.9% (N = 3) and tin separation factor of (6.8 ± 5.5) x 105 (N = 3). Apparent molar activity measurements for deuteron produced 117Sb using the chelator TREN-CAM were measured at 42.4 ± 25 MBq 117Sb/µmol (1.14 ± 0.68 mCi/µmol), and we recovered enriched 119Sn target material at a recycling efficiency of 80.2% ± 5.5% (N = 6) with losses of 11.6 mg ± 0.8 mg (N = 6) per production.ConclusionWe report significant steps in overcoming barriers in 119Sb production, chemical isolation and purification, enriched target material recycling, and chelation, helping promote accessibility and application of this promising therapeutic radionuclide. We describe a method for 119Sb activity measurement using its low energy gamma (23.87 keV), negating the need for attenuation correction. Finally, we report the largest yet-measured 119Sb production yields using proton and deuteron irradiation of natural and enriched targets and radioisotopic purity > 99.8% at end of purification.

Calix[4]arene-decorated polymers of intrinsic microporosity for lithium isotopes separation

Due to the importance of lithium isotopes in the nuclear energy industry, there are increasing number of researchs on the lithium isotopes separation in recent years. However, the adsorbents used for lithium isotopes separation suffer from the low adsorption capacity and isotopes separation factor in aqueous phase, and is difficult to meet the requirements for industrial lithium isotopes production. In this work, two types of calix[4]arenes with different rim groups were incorporated into the polymer backbone. Both calix[4]arene decorated PIMs exhibited good lithium adsorption capacities in aqueous phase. Among them, 4-tert-butyl-calix[4]arene decorated PIM showed excellent lithium isotopes separation performance with a maximum lithium adsorption capacity of 67.99 mg·g−1 and an isotopes separation factor of 1.034 ± 0.003 in aqueous phase. The ease of preparing and stable cycling performance makes it potentially useful for industrial lithium isotopes production.

Isotope Reverse-Labeled Infrared Spectroscopy as a Probe of In-Cell Protein Structure.

While recent years have seen great progress in determining the three-dimensional structure of isolated proteins, monitoring protein structure inside live cells remains extremely difficult. Here, we examine the utility of Fourier transform infrared (FTIR) spectroscopy as a probe of protein structure in live bacterial cells. Selective isotope enrichment is used both to distinguish recombinantly expressed NuG2b protein from the cellular background and to examine the conformation of specific residues in the protein. To maximize labeling flexibility and to improve spectral resolution between label and main-band peaks, we carry out isotope-labeling experiments in "reverse-labeling" mode: cells are initially grown in 13C-enriched media, with specific 12C-labeled amino acids added when protein expression is induced. 1 Because FTIR measurements require only around 20 μL of sample and each measurement takes only a few minutes to complete, isotope-labeling costs are minimal, allowing us to label multiple different residues in parallel in simultaneously grown cultures. For the stable NuG2b protein, isotope difference spectra from live bacterial cultures are nearly identical to spectra from isolated proteins, confirming that the structure of the protein is unperturbed by the cellular environment. By combining such measurements with site-directed mutagenesis, we further demonstrate that the local conformation of individual amino acids can be monitored, allowing us to determine, for example, whether a specific site in the protein contributes to α-helix or β-sheet structures.

Highly enriched carbon and oxygen isotopes in carbonate-derived CO2 at Gale crater, Mars

Carbonate minerals are of particular interest in paleoenvironmental research as they are an integral part of the carbon and water cycles, both of which are relevant to habitability. Given that these cycles are less constrained on Mars than they are on Earth, the identification of carbonates has been a point of emphasis for rover missions. Here, we present carbon (δ13C) and oxygen (δ18O) isotope data from four carbonates encountered by the Curiosity rover within the Gale crater. The carbon isotope values range from 72 ± 2‰ to 110 ± 3‰ Vienna Pee Dee Belemnite while the oxygen isotope values span from 59 ± 4‰ to 91 ± 4‰ Vienna Standard Mean Ocean Water (1 SE uncertainties). Notably, these values are isotopically heavy (13C- and 18O-enriched) relative to nearly every other Martian material. The extreme isotopic difference between the carbonates and other carbon- and oxygen-rich reservoirs on Mars cannot be reconciled by standard equilibrium carbonate-CO2 fractionation, thus requiring an alternative process during or prior to carbonate formation. This paper explores two processes capable of contributing to the isotopic enrichments: 1) evaporative-driven Rayleigh distillation and 2) kinetic isotope effects related to cryogenic precipitation. In isolation, each process cannot reproduce the observed carbonate isotope values; however, a combination of these processes represents the most likely source for the extreme isotopic enrichments.

Proton permeation and selective separation of hydrogen isotopes through fullerene nanocages (X12Y12): A DFT insights

To resolve the problem of mobile electrolytes for the permeation of hydrogen isotopes in fuel cells, we have studied herein heteronuclear fullerene nanocages (Al12N12, Al12P12, B12N12, and B12P12) for the separation and permeation of hydrogen isotopes. The separation and permeation of fullerene nanocages for hydrogen isotopes are studied at ωB97XD functional of DFT along with 6–31g (d,p) pople basis set. Zero-point energy (ZPE) is calculated for Protium (H+) and its heavier isotopes including deuterium (D+) and tritium (T+). The Arrhenius equation is employed to calculate the selectivity of protium to deuterium (H+/D+) and deuterium to tritium (H+/T+) isotopes. The selectivity is calculated by using the zero-point energy difference (ZPE) of protium (H+) to its heavier isotopes. The proposed fullerene nanocages estimated better selectivity for proton isotopes. The phosphide-based nanocages (Al12P12, B12P12) provide superior selectivity values of H+/D+ and H+/T+ compared to nitrogen-based nanocages (Al12N12, B12N12). This study provides insights into separation pathways for proton isotopes through nanocages for many industrial applications in the energy sector.

Feasibility of Photonuclear Transmutation of Long-Lived Fission Products Extracted from Used Nuclear Fuel

To achieve the goal of net-zero carbon emission in energy production, nuclear power capacity and waste generation are expected to expand significantly in the next few decades. In the condition of continuous fuel recycling, long-lived fission products (LLFPs) are dominant contributors to the disposal impacts of nuclear waste. In this study, six LLFPs, including 99Tc, 129I, 135Cs, 126Sn, 93Zr, and 79Se, were identified as the primary contributors to more than 99% of long-term radiotoxicity of disposed nuclear waste across a wide range of fuel cycle scenarios. To reduce the amounts of LLFPs sent to geological repositories, the nuclear transmutation of LLFPs is being pursued. Specifically, this work systematically assessed the feasibility of transmuting LLFPs via photonuclear reactions. Photon transmutation is physically viable for the identified primary LLFPs except for 99Tc. For the five transmutable LLFPs, the achievable photon transmutation performance without isotopic separation was evaluated based on scoping calculations and consideration of nuclear data uncertainties. Using an extremely intense laser Compton photon source of 1019 γ /s, the effective transmutation half-life can be reduced to a few years. However, the absolute transmutation rates of LLFPs remain below 1 kg/yr. The energy required to power the photon source for transmuting all LLFPs produced in a nuclear reactor exceeds the net energy output of the reactor. Several potential strategies for improving photon transmutation performance were analyzed. None can substantially enhance the performance to make it practical for industrial applications.

A model framework for atmosphere–snow water vapor exchange and the associated isotope effects at Dome Argus, Antarctica – Part 1: The diurnal changes

Abstract. Ice-core water isotopes contain valuable information on past climate changes. However, such information can be altered by post-depositional processing after snow deposition. Atmosphere–snow water vapor exchange is one such process, but its influence remains poorly constrained. Here we constructed a box model to quantify the atmosphere–snow water vapor exchange fluxes and the associated isotope effects at sites with low snow accumulation rates, where the effects of atmosphere–snow water vapor exchange are suspected to be large. The model reproduced the observed diurnal variations in δ18O, δD, and deuterium excess (d-excess) in water vapor at Dome C, East Antarctica. According to the same model framework, we found that under average summer clear-sky conditions, atmosphere–snow water vapor exchange at Dome A can cause diurnal variations in atmospheric water vapor δ18O and δD of 4.8 ‰ ± 2.6 ‰ and 29 ‰ ± 19 ‰, with corresponding diurnal variations in surface snow δ18O and δD of 0.80 ‰ ± 0.35 ‰ and 1.6 ‰ ± 2.7 ‰. The modeled results under summer cloudy conditions display similar patterns to those under clear-sky conditions but with much smaller magnitudes of diurnal variations. However, under winter conditions at Dome A, the model predicts few to no diurnal changes in snow isotopes, consistent with the stable boundary condition in winter that inhibits effective vapor exchange between the atmosphere and snow. In addition, after 24 h and continuous simulations of 11 d, the model predicts significant enrichments in snow isotopes under summer conditions, while in winter, the depletions also accumulate after each 24 h simulation but with a much smaller magnitude of change compared to the results from summer simulations. If the modeled snow isotope enrichments in summer conditions and the depletions in winter conditions represent the general situation at Dome A, this likely suggests that atmosphere–snow water vapor exchange tends to increase snow isotope seasonality, and the annual net effect would be overall enrichments in snow isotopes since the effects in summer appear to be greater than those in winter. This trend will need to be further explored in the future with more comprehensive model studies and/or field observations and experiments.

Isotope Evidence for Rice Accumulation of Newly Deposited and Soil Legacy Cadmium: A Three-Year Field Study.

Biogeochemical processes of atmospherically deposited cadmium (Cd) in soils and accumulation in rice were investigated through a three-year fully factorial atmospheric exposure experiment using Cd stable isotopes and diffusive gradients in thin films (DGT). Our results showed that approximately 37-79% of Cd in rice grains was contributed by atmospheric deposition through root and foliar uptake during the rice growing season, while the deposited Cd accounted for a small proportion of the soil pools. The highly bioavailable metals in atmospheric deposition significantly increased the soil DGT-measured bioavailable fraction; yet, this fraction rapidly aged following a first-order exponential decay model, leading to similar percentages of the bioavailable fraction in soils exposed for 1-3 years. The enrichment of light Cd isotopes in the atmospheric deposition resulted in a significant shift toward lighter Cd isotopes in rice plants. Using a modified isotopic mass balance model, foliar and root uptake of deposited Cd accounted for 47-51% and 28-36% in leaves, 41-45% and 22-30% in stems, and 45-49% and 26-30% in grains, respectively. The implications of this study are that new atmospheric deposition disproportionately contributes to the uptake of Cd in rice, and managing emissions thus becomes very important versus remediation of impacted soils.

Evidence for Surprising Heavy Nitrogen Isotopic Enrichment in Comet 46P/Wirtanen’s Hydrogen Cyanide

46P/Wirtanen is a Jupiter-family comet, probably originating from the solar system’s Kuiper Belt, that now resides on a 5.4 yr elliptical orbit. During its 2018 apparition, comet 46P passed unusually close to the Earth (within 0.08 au), presenting an outstanding opportunity for close-up observations of its inner coma. Here we present observations of HCN, H13CN, and HC15N emission from 46P using the Atacama Compact Array. The data were analyzed using the SUBLIME non-LTE radiative transfer code to derive 12C/13C and 14N/15N ratios. The HCN/H13CN ratio is found to be consistent with a lack of significant 13C fractionation, whereas the HCN/HC15N ratio of 68 ± 27 (using our most conservative 1σ uncertainties), indicates a strong enhancement in 15N compared with the solar and terrestrial values. The observed 14N/15N ratio is also significantly lower than the values of ∼140 found in previous comets, implying a strong 15N enrichment in 46P’s HCN. This indicates that the nitrogen in Jupiter-family comets could reach larger isotopic enrichments than previously thought, with implications for the diversity of 14N/15N ratios imprinted into icy bodies at the birth of the solar system.

Effects of Short‐Term Climate Variations on Young Water Fraction in a Small Pre‐Alpine Catchment

AbstractContinuous and extended observations of hydrometeorological parameters, alongside the analysis of the isotopic composition across diverse waters within catchments, can significantly enhance our understanding of the potential ramifications of climate change on the hydrological response. In this study, a comprehensive analysis of hydrometeorological and isotopic data was conducted over 10 hydrological years (October 2012–September 2022) within a small, forested catchment in the Italian pre‐Alps, aiming to investigate the impacts of short‐term climatic changes on the isotopic composition of waters and the young water fraction (Fyw). The results showed that the catchment experienced climate conditions with rapid warming and drying trends. Significant isotopic enrichments were observed in all sampled water sources, driven primarily by air temperature. Fyw was estimated to be 0.64 ± 0.06, 0.45 ± 0.07, and 0.16 ± 0.03 for stream water, soil water, and shallow groundwater based on the whole‐period sinusoidal fittings, respectively. Comparative analyses comprising different approaches for the estimation of Fyw showed that time‐windows scenarios and detrending corrections yielded smaller Fyw than approaches based on the whole‐period fitting and discharge‐sensitivity modeling. Such differences can be attributed to an uneven temporal distribution of stream water isotopic data, the difficulties in capturing high flows in a humid catchment characterized by a fast runoff response during rainfall‐runoff events, and the presence of isotopic trends. Our findings underscore the imperative of integrating interannual isotopic trends and adopting appropriate sampling strategy and methodological approaches to ensure a robust Fyw estimation.

Metal-doped amorphous microporous carbon for isotope separation: Pore size modulation and selective deuterium adsorption

Efficient hydrogen isotope separation is crucial for applications in energy production and advanced scientific research, but separation of these poses significant challenges. In this study, we developed amorphous microporous carbon (AMC) derived from a zeolite template and explored hydrogen isotope separation using quantum sieving. Thermal desorption spectroscopy (TDS) technique was used to evaluate the selectivity of hydrogen (H2) and deuterium (D2) isotope separation. The doping of metal ions, such as Ca2⁺, Mg2⁺, Ni2⁺, and Cu2⁺, in the porous carbon modulates the physicochemical properties of the pores. The metal-doped carbon samples demonstrated D2vs H2 selectivity (SD2/H2) of over 10, compared to the pristine carbon's SD2/H2 of less than 8. Density functional theory (DFT) calculation infers that pore modulation through metal doping enhanced the binding affinity of materials towards D2 resulting in increased separation selectivity compared to pristine carbon samples. This approach not only boosts separation efficiency but also provides a scalable and cost-effective solution for industrial applications.

High-Precision Mass Measurements of Neutron Deficient Silver Isotopes Probe the Robustness of the N=50 Shell Closure.

High-precision mass measurements of exotic ^{95-97}Ag isotopes close to the N=Z line have been conducted with the JYFLTRAP double Penning trap mass spectrometer, with the silver ions produced using the recently commissioned inductively heated hot cavity catcher laser ion source at the Ion Guide Isotope Separator On-Line facility. The atomic mass of ^{95}Ag was directly determined for the first time. In addition, the atomic masses of β-decaying 2^{+} and 8^{+} states in ^{96}Ag have been identified and measured for the first time, and the precision of the ^{97}Ag mass has been improved. The newly measured masses, with a precision of ≈1 keV/c^{2}, have been used to investigate the N=50 neutron shell closure, confirming it to be robust. Empirical shell-gap and pairing energies determined with the new ground-state mass data are compared with the state-of-the-art abinitio calculations with various chiral effective field theory Hamiltonians. The precise determination of the excitation energy of the ^{96m}Ag isomer in particular serves as a benchmark for abinitio predictions of nuclear properties beyond the ground state, specifically for odd-odd nuclei situated in proximity to the proton dripline below ^{100}Sn. In addition, density functional theory calculations and configuration-interaction shell-model calculations are compared with the experimental results. All theoretical approaches face challenges to reproduce the trend of nuclear ground-state properties in the silver isotopic chain across the N=50 neutron shell and toward the proton dripline.