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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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126 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Quantifying the Lewis Acidity of Mono-, Di-, and Trivalent Cations in Anhydrous Bis(trifluoromethylsulfonyl)imide Salts

While the bis(trifluoromethylsulfonyl)imide anion (TFSI – ; formula [N(SO 2 CF 3 ) 2 ] – ) has been noted for its practical utility, the use of TFSI – salts as sources of Lewis acidic metal cations for studies of cation-driven tuning effects has not been reported. Here, the effective Lewis acidity of mono-, di-, and trivalent cations (namely, K + , Na + , Li + , Ba 2+ , Ca 2+ , Mg 2+ , Zn 2+ , La 3+ , Y 3+ , Lu 3+ , and Sc 3+ ) in the form of their TFSI – salts is described, along with quantitative comparisons to salts of several other weakly coordinating anions (namely, SO 3 CF 3 – , PF 6 – , and BArF 24 – ). Triphenylphosphine oxide (TPPO) was used as a 31 P NMR probe in titration experiments for quantification of key parameters describing the effective Lewis acidity of the salts in acetonitrile (CH 3 CN) solutions. Notably, the TFSI – salts of di- and trivalent cations were found to display strong binding to TPPO with significant speciation and were found to be quite hygroscopic. Taken together, the measurements demonstrate that TFSI – salts are systematically better/stronger effective Lewis acids than their triflate analogues. And, considering the excellent solubility of TFSI – salts, these materials appear attractive for further use and development in Lewis-acidity-dependent applications, including catalysis and tuning of multimetallic materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

𝑁 = 8 Shell Breaking in 12 Be from a Single-Particle Perspective

Experimental observations of the low-lying states in 12 Be and their accurate modeling play an essential role in understanding the disappearance of the 𝑁 = 8 magic number. Long-standing experimental ambiguities have been clarified using an one-neutron adding (𝑑, 𝑝) reaction on 11 Be using the ISOLDE Solenoidal Spectrometer at CERN’s HIE-ISOLDE facility. The single-particle energies of 1⁢𝑠 1/2 , 0⁢𝑑 5/2 , and 0⁢𝑝 1/2 orbitals in 12 Be have been determined from the extracted spectroscopic factors. A significant reduction between the separation of 1⁢𝑠 1/2 and 0⁢𝑝 1/2 orbitals is found in comparison with the carbon isotones, highlighting the breakdown of the 𝑁 = 8 shell. These observations serve as an important test of different effects incorporated in theoretical models. It is found that two synergistic mechanisms, core deformation and weak binding, are responsible for the 𝑁 = 8 shell breaking and the exotic near-threshold phenomena observed in 12 Be, including the narrow unnatural-parity resonance $0^{-}_1$ and the possible halolike nature of the $0^+_2$ isomer.

Chen, Jie [Southern University of Science and Tech↗
DOE OSTI2024

Quantum Simulations of Radiation Damage in a Molecular Polyethylene Analog

Abstract An atomic‐level understanding of radiation‐induced damage in simple polymers like polyethylene is essential for determining how these chemical changes can alter the physical and mechanical properties of important technological materials such as plastics. Ensembles of quantum simulations of radiation damage in a polyethylene analog are performed using the Density Functional Tight Binding method to help bind its radiolysis and subsequent degradation as a function of radiation dose. Chemical degradation products are categorized with a graph theory approach, and occurrence rates of unsaturated carbon bond formation, crosslinking, cycle formation, chain scission reactions, and out‐gassing products are computed. Statistical correlations between product pairs show significant correlations between chain scission reactions, unsaturated carbon bond formation, and out‐gassing products, though these correlations decrease with increasing atom recoil energy. The results present relatively simple chemical descriptors as possible indications of network rearrangements in the middle range of excitation energies. Ultimately, the work provides a computational framework for determining the coupling between nonequilibrium chemistry in polymers and potential changes to macro‐scale properties that can aid in the interpretation of future radiation damage experiments on plastic materials.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

129 I, 99 Tc, and U Distribution Coefficients of Subsurface Sediments Collected from the Proposed Site of the Environmental Management Disposal Facility

Performance Assessment calculations were completed in 2020 to evaluate the Environmental Management Disposal Facility (EMDF), a proposed new low-level radioactive waste (LLW) disposal facility on the U.S. Department of Energy’s Oak Ridge Reservation (ORR). Among the large number of input parameters needed for such calculations, are distribution coefficients (K d values; radionuclide concentration solid: liquid ratio) that provide a measure of the tendency of radionuclides to bind to sediments. The objective of this study was to measure K d values of three radionuclides that may pose a disproportionately large amount of risk, U, iodine-129 ( 129 I) and technetium-99 ( 99 Tc). The average 129 I K d value for the 14 geological materials recovered from the proposed EMDF site was 37.8 mL/g and ranged from 0.45 to 140.9 mL/g. These values were consistent, but somewhat larger than previous measurements made with ORR sediments and were about an order of magnitude greater than those used in previous EMDF PA calculations. The median 99 Tc K d value was 365.7 mL/g, much greater than previously reported using ORR geological materials. Five of the 14 tested geological materials sorbed large quantities of 99 Tc, suggesting that the weakly sorbing 99 Tc(VII) species had been reduced to the sparingly soluble 99 Tc(IV) species. The five strongly sorbing sediments had apparent 99 Tc solubility values of approximately <10 -8 mol/L. The median U K d value was 5,726 mL/g. All of the tested geological materials had large K d values, ranging from 625 to >10,208 mL/g. Among the sediment samples that exhibited strong U binding, the apparent solubility value was approximately <10 -9 mol/L. Based on sediment properties and general ORR geological considerations, it was proposed that much of the 129 I and 99 Tc retention could be attributed to the site materials exhibiting low pH (average pH = 4.94), and/or the elevated levels of iron oxides, manganese oxides, and natural organic matter. Similarly, the extremely high U binding measured in these sediments may also be attributed to the low conditions of carbonates, which can complex and therefore solubilize uranyl in these tests due to the low pH, and also the relatively high concentrations of iron and organic coatings on these samples. An implication of this study is that the areas of the EMDF subsurface environment may have natural properties for attenuating 129 I, 99 Tc, and U movement, and potentially other radionuclides, thereby possibly reducing risk posed by burial of LLW at this site.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Enhancing Selective Hydrofluorocarbon Greenhouse Gas Capture via Halogenation of Metal–Organic Frameworks

Hydrofluorocarbons (HFCs) are anthropogenically produced greenhouse gases with longer atmospheric lifetimes and higher global warming potentials than those of carbon dioxide. General strategies to abate their emissions from industrial point sources, such as via adsorptive capture, remain scarce. Herein, we uncover the key structure–property relationships that lead to strong binding of HFCs such as fluoroform (CHF 3 ) and difluoromethane (CH 2 F 2 ) in metal–organic frameworks (MOFs) under the low pressures relevant to flue gas scrubbing. Extensive gas sorption and computational studies support that the Zr-based microporous framework MOF-801-Br or HHU-2-Br (HHU = Heinrich-Heine-University Düsseldorf) strongly binds HFCs due to its synergistic combination of Zr-OH sites on the nodes and bromine sites on the linkers. As such, MOF-801-Br demonstrates a record-setting performance for separating CHF 3 from N 2 under dilute conditions. Our work highlights that the combination of multiple hydrogen-bonding sites in microporous MOFs represents a generalizable strategy for HFC capture, enabling their selective removal from industrial waste streams.

adsorption↗
DOE OSTI2026

Protein Adhesion on Semi-Fluorinated Polystyrene Surfaces in Static and Dynamic Measurements

Reducing protein adhesion is a critical strategy in fouling-resistant material innovation, with broad applications spanning biomedical and healthcare devices, biosensors, industrial and environmental systems, and other important technological domains. Here, in this study, we elucidated protein adhesion behavior on polystyrene-based thin films by neutron reflectometry (NR) and quartz crystal microbalance with dissipation (QCM-D), using both lysozyme and bovine serum albumin (BSA) as model proteins. To this end, semifluorinated polystyrene thin films with gradient wettability and surface energy were fabricated through dry processing using plasma oxidation and gas-phase deposition. Although it is believed that a fully fluorinated alkyl chain offers extremely low surface energy, thus rejecting foulants, and has been used in many fouling-resistant surface designs, enhanced protein–surface interactions were observed consistently in NR and QCM-D results, due to the combined effects of surface morphology and chemistry. On the contrary, depositing shorter fluorinated silane onto a hydrophilic PS surface contributed to a more homogeneous nanoscale fluorine coating, resulting in less initial protein adsorption and improved surface recovery. Comparative analysis of proteins with different sizes on the nanopatterned semifluorinated surface revealed the influence of molecular characteristics on surface interactions. Lysozyme, being smaller and more compact, showed faster adsorption kinetics and higher surface coverage but largely reversible binding, whereas BSA, with its larger and more flexible structure, formed broader and more stable interfacial layers. This study fills the gap in understanding protein adhesion within the range of hydrophobicity (water contact angle ∼90°), as current strategies often associate with extreme hydrophilic and superhydrophobic surfaces due to hydration or low-surface-energy rejection mechanisms, respectively. It also provides in-depth insights into current combinatorial fouling-resistant surface design.

Yuan, Yue [Oak Ridge National Laboratory (ORNL), O↗
DOE OSTI2024

First-principles investigation of lanthanides diffusion in HCP zirconium via vacancy-mediated transport

The diffusion of lanthanide fission products plays an important role in the growth of the fuel-cladding chemical interaction (FCCI) region in metallic fuels. The use of a Zr interdiffusion barrier may mitigate the transport of lanthanides from the fuel to the cladding, but the efficacy of such a liner is not yet known. In this paper, the stability and vacancy-mediated diffusion of La, Ce, Pr, and Nd in hexagonal close-packed (HCP) Zr is investigated via density functional theory (DFT) calculations and self-consistent mean field (SCMF) analysis. DFT is used to calculate the formation, binding, and migration energies of vacancies and vacancy-solute pairs. The DFT energetics are used in the KineCluE code to calculate the Onsager transport coefficients. La is found to be the fastest diffusing species in HCP Zr and experiences an almost isotropic diffusion behavior. The other three species (Ce, Pr, and Nd) demonstrate anisotropic diffusion where the diffusion in the basal planes is significantly faster than that along the c-axis. Further, the calculated lanthanide diffusivities in HCP Zr are fitted to an Arrhenius relation and the activation energies and prefactors are reported for the first time. Furthermore, the vacancy drag and the segregation tendencies were analyzed using the calculated off-diagonal transport coefficients. According to our vacancy-mediated diffusion model, lanthanides are expected to be enriched at vacancy sinks at low temperatures, while at high temperatures, lanthanides are depleted at sinks and will preferably diffuse into the bulk. The enrichment/depletion transition temperature depends on the diffusion direction (basal or axial) and hence will be controlled by the grain texture and orientation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Understanding the effect of minor alloying elements on helium bubble formation in ferritic-martensitic steels

Ferritic-martensitic steels are promising structural materials for advanced nuclear reactors. To minimize long-term radioactivity, reduced-activation ferritic-martensitic steels have been developed by substituting high-activation elements like Ni and Mo with low-activation elements such as W. However, the impact of these alloying modifications on helium bubble formation, which plays a key role in material swelling, remains unclear. Here, in this study, we compared helium bubble formation in ferritic-martensitic steel T91 and reduced-activation ferritic-martensitic steel F82H. Both materials were irradiated with sequential 100 keV, 150 keV, and 200 keV helium ions to a dose of 0.5 dpa and a helium concentration of 9,000 appm at 500°C. The helium bubbles in F82H exhibited a larger average size and a lower density than those in T91, suggesting differences in minor alloying elements may influence the bubble growth. Here, to investigate the effects of these alloying elements, we characterized radiation-induced segregation near bubbles and grain boundaries. Prominent Ni-Mn-Si enriched clusters were found near bubbles in T91, while only Mn-Si enriched clusters were found near bubbles in F82H. In addition, the obvious Cr enrichment near grain boundaries was absent around bubbles in both steels. The different segregation trends among elements revealed the variations in element diffusion mechanisms and the different sink biases between bubbles and grain boundaries. Cr enrichment near grain boundaries is mostly driven by interstitial-mediated diffusion. However, since bubble growth relies on net vacancy flux, vacancy-mediated diffusion plays a dominant role in controlling element segregation near bubbles. Therefore, Cr enrichment was not found near bubbles. Because of preferential vacancy-drag diffusion for Ni, Si and Mn, these elements were enriched near bubbles. Due to the strong binding energies of vacancies with these solute atoms, the vacancy diffusivity can be reduced near these solutes. Therefore, the more prominent Ni-Si-Mn clustered near helium bubbles in T91 lead to stronger suppression of helium bubble growth compared to F82H.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Enhanced sensitivity for electron affinity measurements of rare elements

The electron affinity (EA), the energy released when a neutral atom binds an additional electron, is a fundamental property of atoms that is governed by electron-electron correlations and is strongly related to an element’s chemical reactivity. However, conventional techniques for EA determination lack the experimental sensitivity to probe very scarce samples. As a result, the EA for the heaviest elements of the periodic table is entirely uncharted. Here, we present a novel technique to determine EAs through Laser Photodetachment Threshold Spectroscopy, performed in an electrostatic ion beam trap to increase the samples’ exposure to laser photons and, thus, improve the experimental signal sensitivity by three orders of magnitude. Moreover, the additional exposure time allows the use of lower-power continuous-wave narrow-band lasers that reduce uncertainties associated with broadening effects induced by the laser bandwidth. By applying this technique, we measure the EA of 35 Cl to be 3.612720(44) eV, achieving state-of-the-art precision while employing five orders of magnitude fewer anions. The demonstrated sensitivity paves the way for systematic EA measurements across isotopic chains - including isotope shifts and hyperfine splittings - and ultimately for the first direct determination of electron affinities in superheavy elements.

Maier, F. M. [Univ. of Greifswald (Germany); Europ↗
DOE OSTI2025

Neutron matter from local chiral effective field theory interactions at large cutoffs

Neutron matter is an important many-body system that provides valuable constraints for the equation of state (EOS) of neutron stars. Neutron-matter calculations employing chiral effective field theory (EFT) interactions have been extensively used for this purpose. Among the various many-body methods, quantum Monte Carlo (QMC) methods stand out due to their nonperturbative nature and the achievable precision. However, QMC methods require local interactions as input, which leads to the appearance of stronger regulator artifacts compared to nonlocal interactions. To circumvent this, we employ large-cutoff interactions derived within chiral EFT (400 MeV ≤ Λ 𝑐 ≤ 700MeV) for studies of pure neutron matter. These interactions have been adjusted to nucleon-nucleon scattering phase shifts, the triton binding energy, as well as the triton 𝛽-decay half-life. We find that regulator artifacts significantly decrease with increasing cutoff, leading to a significant reduction of uncertainties in the neutron-matter EOS. We discuss implications for the symmetry energy and demonstrate how our new calculations lead to a reduction in the theoretical uncertainty of predicted neutron-star radii by up to 30% for low-mass stars.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Adsorption of terbium (III) on DGA and LN resins: Thermodynamics, isotherms, and kinetics

Two commercially available extraction chromatography (EXC) resins containing N,N,N’,N’-tetra-n-octyldiglycolamide (DGA Resin, Normal, 50 – 100 μm) and Bis(2-ethylhexyl) phosphate (LN Resin, 100 – 150 μm) were used as adsorbents to study fundamental adsorption properties such as thermodynamic values, equilibrium isotherms, and kinetic uptake models for terbium(III) adsorption. Weight distribution ratios (D w ) for terbium on DGA and LN resins were measured using a [ 160 Tb]Tb 3+ radiometric tracer in nitric acid as a function of acidity, temperature, initial analyte concentration, and equilibrium time. The D w values showed increasing binding affinity for DGA resin at high nitric acid concentrations and decreasing binding affinity for LN resins. Thermodynamic studies for DGA and LN resins revealed that the Gibbs free energy (ΔG) increased consistently with temperature. To model equilibrium data, increasingly higher parameter equilibrium isotherm models (Henry (1) < Langmuir, Freundlich (2) < Redlich-Peterson (3) < Fritz-Schluender (4)) were compared on their root mean squared errors (RMSE) and adjusted determination coefficients to determine the most applicable model. In all cases, the empirical four-parameter Fritz-Schluender isotherm demonstrated a superior fit. Similar comparisons for reaction-based kinetic models (Pseudo-first-order < Pseudo-second-order < Pseudo-n-order) revealed that the higher-order PNO model yielded a superior fit of kinetic data for both resins. Furthermore, in some cases, adsorption isotherms and kinetic models could also be modeled by a lower-order model with minimal change in error parameters. Weber-Morris plots revealed that two linear sections are observed for each resin, where the first linear segment is attributed to fast (film diffusion) adsorption of terbium, followed by slower intraparticle diffusion of terbium through the pores as the rate-limiting step. Based on the Weber-Morris plot, both film and intraparticle diffusion are involved in controlling the kinetic rate of adsorption for DGA and LN resins.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2026

Native Architecture of Wheat Straw Cell Walls: A Unified Model from X-ray Scattering and Solid-State NMR

Plant secondary cell walls constitute the dominant reservoir of renewable biomass, comprising tightly packed cellulose, hemicellulose, and lignin at the nanoscale. Recent advances in solid-state NMR spectroscopy and the availability of small-angle X-ray scattering for biomass characterization have led to an accumulation of experimental data on cell wall organization, yet no explicit structure model has simultaneously satisfied both Xray and NMR observations. Using wheat straw as a model system, we propose a structural framework consistent with current knowledge of cellulose biosynthesis, X-ray scattering data, and one- and two-dimensional 13 C solid-state NMR spectra. In this model, 18-chain elementary fibrils align in parallel and populate the cross-section at random. Arabinose-substituted xylan shows no conformational dependence for cellulose-binding in wheat, and only a minor fraction of 2-fold xylan appears in close proximity to cellulose, unlike in Arabidopsis, where xylan is more tightly attached to the cellulose surface. While NMR data cannot unambiguously resolve the internal arrangement of the 18 glucan chains, X-ray scattering profiles uniquely constrain the fibril size and exclude the possibility of tight bundling in the intact walls. The specific interaction between the matrix polymers and the cellulose elementary fibrils must be reconsidered in light of the small interfibril spaces, which bring the matrix components into spatial proximity with cellulose even in the absence of attractive interactions. These findings provide fundamental molecular-level insight into cellulose fibril architecture and matrix−polymer interactions, resolving longstanding discrepancies between spectroscopic and scattering data and advancing our understanding of biopolymer assembly into structurally and functionally versatile lignocellulosic biomaterials.

Carbohydrates↗
DOE OSTI2025

Energetic and Electronic Properties of UX +/0/– for X = Li and Be and Comparison of the Properties of the Uranium Atom Binding to 2nd Row Elements Li–F

The bonding and spectroscopic properties of ULi +/0/– and UBe +/0/– to complete the series for UX +/0/– for X = Li to F were investigated by high-level ab initio SO-CASPT2 and CCSD(T) electronic structure calculations. The low-lying spin–orbit states were obtained at the SA-CASPT2/aQ-PP level; bond dissociation energies (BDEs), ionization energies (IEs), adiabatic electronic affinities (AEAs), and vertical detachment energies (VDEs) were calculated at the Feller-Peterson-Dixon (FPD) level. A dense manifold of low-lying states was predicted for ULi +/0/– and UBe +/0/– . Here, the calculated BDEs for ULi (37.7 kJ/mol) and UBe (8.0 kJ/mol) show that UBe is weakly bound. For redox processes, the BDEs increased for ULi + (109.3 kJ/mol), ULi – (47.4 kJ/mol), UBe + (35.6 kJ/mol), and UBe – (72.3 kJ/mol). The IE(ULi) = 4.650 eV is lower than IE(Li); the IE(UBe) = 5.901 eV is close to the IE(U) and to the IEs of UB, UC, UN, UO, and UF. The AEAs of ULi (0.708 eV) and UBe (0.989 eV) are lower than those for UB, UC, UN, and UO but higher than that for EA(UF). Natural bond orbital (NBO) calculations show that ULi has the 5f 3 6d 1 7s 2 configuration for U and 2s 1 for Li, with a small partial negative charge slightly delocalized on U. UBe arises from the U(5f 3 6d 1 7s 2 ) and Be(2s 2 ) electron configurations with no charge separation. The same calculations were made for WX (X = Li, Be, C–F) to enable detailed comparisons of the properties for UX with WX (X = Li–F). For WX, BDE(WX) is higher than that for UX for X = Li to N and lower than BDE(UX) for X = O and F, mostly due to the higher IE of W than U as ionic character becomes more important going from Li to F.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Orientation-dependent enhanced ionization in acetylene revealed by ultrafast cross-polarized pulse pairs

We investigate the orientation dependence of enhanced ionization (EI) during strong-field-driven nuclear motion in acetylene (C 2 ⁢H 2 ). Here, we both initiate and probe molecular dynamics in acetylene with intense 6-fs cross-polarized pulse pairs, separated by a variable delay. Following multiple ionization by the first pulse, acetylene undergoes simultaneous elongation of the carbon-carbon and carbon-hydrogen bonds, enabling further ionization by the second pulse and the formation of a very highly charged state, [C 2 ⁢H 2 ] 6+ . At small interpulse delays (< 20 fs), this enhancement occurs when the molecule is aligned to the probe pulse. Conversely, at large delays (> 40 fs), formation of [C 2 ⁢H 2 ] 6+ occurs when the molecule is aligned to the pump pulse. By analyzing the polarization and time dependence of sequentially ionized [C 2 ⁢H 2 ] 6+ , we resolve two transient alignments that both contribute to a large increase in the multiple ionization yield. In conclusion, this cross-polarized pulse pair scheme uniquely enables selective probing of deeply bound orbitals, providing new insights on orientation-dependent EI in highly charged hydrocarbons.

Atomic & molecular clusters↗
DOE OSTI2025

Barium ion sensing with IPG K + molecular probes

Fluorophores covalently bound to azacrown ether ionophores can be assembled into sensitive turn-on chemosensors. The size specificity and electron-rich nature of the ionophore's binding domain contribute to both selectivity and strong turn-on fluorescence sensing by various mechanisms when properly constructed. Aza-18-crown-6 ethers are quite selective for binding to K + and Ba 2+ , yet the more electron-withdrawing dicationic nature of barium imposes a larger electronic effect on turn-on fluorescent sensors. Barium chemosensors can be important for measuring soluble Ba 2+ in drinking water and have gained recent attention for their potential to enhance the detection of rare events in xenon decay. Here we quantify the capability of three chemosensors, marketed for biologically useful K + sensing, as effective probes for Ba 2+ ions. Here, we present measurements from bulk spectrofluorometry to characterize the system in aqueous solutions and demonstrate the usefulness of these species for low-background single-ion fluorescence microscopy, revealing new candidates for Ba 2+ sensing.

Miller, R. L. [Department of Chemistry and Biochem↗
DOE OSTI2025

Resonant inelastic X-ray scattering tools to count 5 $f$ electrons of actinides and probe bond covalency

The actinides possess a complex electronic structure, making their chemical and physical properties among the least understood in the periodic table. Advanced spectroscopic tools, able to obtain deep insights into the electronic structure and binding properties of the actinides, are highly desirable. Here, we introduce two sensitive spectroscopic tools: one determines the number of localized 5f electrons on an actinide atom, and another assesses the covalent character of actinide-ligand bonding. Both tools are based on the multiplet structure present in actinide M 4 edge core-to-core resonant inelastic X-ray scattering (CC-RIXS) maps. The spectral intensity of different many-body final-state multiplets directly depends on the local many-electron ground-state symmetry including the local 5 f spin configuration. By comparing U M 4 edge CC-RIXS data for 21 U, Np, Pu and Am compounds, we demonstrate the ability to compare the number of localized 5 f electrons and bond covalency across the actinide series.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Exploring the onset of collectivity approaching 𝑁=40 with masses of manganese isotopes

Isotopes in the region of the nuclear chart below 68 Ni have been the subject of intense experimental and theoretical effort due to the potential onset of a new “island of inversion” when crossing the harmonic oscillator subshell closure at 𝑁=40. Here, we have measured the masses of 64−68 Mn using TITAN's multiple-reflection time-of-flight mass spectrometer, resulting in the first precision mass measurements of 67 Mn and 68 Mn. These results are compared to ab initio calculations and modern shell model calculations and show an increase in collectivity approaching 𝑁=40.

binding energy & masses↗