Monolayer-Based Single-Photon Source in a Liquid-Helium-Free Open Cavity Featuring 65% Brightness and Quantum Coherence
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36 MATERIALS SCIENCE↗
SEARCH · Engineering Papers
Results for “resonance structures”
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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Unlocking Efficient Ultrafast Bound-Electron Optical Nonlinearities via Mirror Induced Quasi Bound States in the Continuum
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77 NANOSCIENCE AND NANOTECHNOLOGY↗
Ring-Opening in the Actinide Cyclopropyl Complexes [Cp 3 U(2,2-Diphenylcyclopropyl)] n – ( n = 0, 1)
The reaction of [Cp 3 UCl] with in situ generated 1-lithium-2,2-dipenylcyclopropane results in the formation of [Cp 3 U(2,2-diphenylcyclopropyl)] (1) in good yield. Reduction of 1 with KC 8 , in the presence of 2.2.2-cryptand, results in the formation of a rare U(III) alkyl complex, [K(2.2.2-cryptand)][Cp 3 U(2,2-diphenylcyclopropyl)] (2). Thermolysis or photolysis of 1 for 10 d in toluene results in isomerization to the U(IV) η 1 -allyl complex, [Cp 3 U(η 1 -3,3-diphenylallyl)] (3). Moreover, photolysis of 2 in THF for 9 h at room temperature results in isomerization to the U(III) η 1 -allyl complex, [K(2,2,2-cryptand)][Cp 3 U(η 1 -3,3-diphenylallyl)] (4). Both 3 and 4 were fully characterized. Additionally, selective labeling of the C α positions of 1 and 2 with deuterium revealed that cyclopropyl ring-opening occurs via distal C–C bond cleavage via a hypothesized η 3 -allyl intermediate.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
The Curious Case of [AnH(NR 2 ) 3 ] (An = Th, U; R = SiMe 3 ): Two Monomeric Actinide Hydrides Revisited
The reaction of AnCl 4 (DME) x (An = Th, x = 2; An = U, x = 0) with 4 equiv of NaNR 2 (R = SiMe 3 ) in THF at 65 °C results in the formation of [An{N(R)(SiMe 2 CH 2 )}(NR 2 ) 2 ] (An = U, 1; An = Th, 2), and not the reported monomeric actinide hydrides, [AnH(NR 2 ) 3 ], as expected. Furthermore, both complexes 1 and 2 were characterized by X-ray crystallography. Surprisingly, their unit cell parameters are remarkably close to those reported for [AnH(NR 2 ) 3 ], suggesting that the original crystals of [AnH(NR 2 ) 3 ] were, in fact, [An{N(R)(SiMe 2 CH 2 )}(NR 2 ) 2 ], but were misidentified. Reduction of 1 with 1.1 equiv of KC 8 in THF, in the presence of 1 equiv of 2.2.2-cryptand, results in the formation of [K(2.2.2-cryptand)][U{N(R)(SiMe 2 CH 2 )}(NR 2 ) 2 ] (3) in good yield. Likewise, the reaction of 1 with 1 equiv of bis(diisopropylamino)cyclopropenylidene (BAC) results in the formation of the BAC adduct, [(BAC)U{N(R)(SiMe 2 CH 2 )}(NR 2 ) 2 ] (4), in moderate yield. Finally, the addition of H 2 (10 bar) to 2 in C 6 D 6 at room temperature results in the formation of the targeted monomeric hydride, [ThH(NR 2 ) 3 ], in 32% yield, according to integrations against an internal standard. However, removal of the H 2 atmosphere results in rapid reformation of 2. In contrast, the addition of H 2 (10 bar) to 1 in C 6 D 6 at room temperature results in no apparent reaction.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Machine Intelligence-Centered System for Automated Characterization of Functional Materials and Interfaces
Classic design of experiment relies on a time-intensive workflow that requires planning, data interpretation, and hypothesis building by experienced researchers. Here, in this paper, we describe an integrated, machine-intelligent experimental system which enables simultaneous dynamic tests of electrical, optical, gravimetric, and viscoelastic properties of materials under a programmable dynamic environment. Specially designed software controls the experiment and performs on-the-fly extensive data analysis and dynamic modeling, real-time iterative feedback for dynamic control of experimental conditions, and rapid visualization of experimental results. The system operates with minimal human intervention and enables time-efficient characterization of complex dynamic multifunctional environmental responses of materials with simultaneous data processing and analytics. The system provides a viable platform for artificial intelligence (AI)-centered material characterization, which, when coupled with an AI-controlled synthesis system, could lead to accelerated discovery of multifunctional materials.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Detecting, Distinguishing, and Spatiotemporally Tracking Photogenerated Charge and Heat at the Nanoscale
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77 NANOSCIENCE AND NANOTECHNOLOGY↗
A Hybrid Molecular–Nanophotonic Platform for On-Chip Cavity Quantum Electrodynamics and Collective Interactions
We present a hybrid solid-state cavity quantum electrodynamics (QED) platform that integrates a high density of coherent organic molecules with high-quality-factor nanophotonics. Thin anthracene crystals doped with dibenzoterrylene (DBT) are mechanically transferred onto prefabricated silicon nitride photonic crystal cavities, preserving both the cavity quality and molecular coherence. This approach decouples emitter synthesis from nanofabrication, providing a pathway for integrating other types of emitters. The high density of molecular emitters results in up to ten molecules being coupled to a single cavity. By tuning pairs of molecules into resonance within a single cavity mode, we observe cavity-mediated interactions in both dispersive and dissipative regimes. Furthermore, these results establish an accessible route to deterministic on-chip single- and multiphoton sources.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Experimental Implementation of Achromatic Multiresonant Metasurface for Broadband Pulse Delay
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Magnetic Interactions in Substitutional Core-Doped Graphene Nanoribbons
The design of a spin imbalance within the crystallographic unit cell of bottom-up engineered 1D graphene nanoribbons (GNRs) gives rise to nonzero magnetic moments within each cell. Here, we demonstrate the bottom-up assembly and spectroscopic characterization of a one-dimensional Kondo spin chain formed by a chevron-type GNR (cGNR) physisorbed on Au(111). Substitutional nitrogen core doping introduces a pair of low-lying occupied states per monomer within the semiconducting gap of cGNRs. Charging resulting from the interaction with the gold substrate quenches one electronic state for each monomer, leaving behind a 1D chain of radical cations commensurate with the unit cell of the ribbon. In this work, scanning tunneling microscopy (STM) and spectroscopy (STS) reveal the signature of a Kondo resonance emerging from the interaction of $\textit{S}$ = 1/2 spin centers in each monomer core with itinerant electrons in the Au substrate. STM tip lift-off experiments locally reduce the effective screening of the unpaired radical cation being lifted, revealing a robust exchange coupling between neighboring spin centers. First-principles DFT-LSDA calculations support the presence of magnetic moments in the core of this GNR when it is placed on Au.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Tetravalent Cerium Alkyl and Benzyl Complexes
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Quantitative Determination of Electronic Effects in Free Radicals through Open-Shell Hammett Substituent Constants
Hammett substituent constants (σ), which quantify the electronic effects of functional groups, are widely used for predicting the properties of organic compounds and investigating reaction mechanisms. While these values have been obtained for a wide range of closed-shell substituents, measurements of analogous values for open-shell substituents are rare due to challenges associated with their short lifetimes. Here, in this report, we developed a combined experimental and computational approach for quantifying the electronic properties of open-shell substituents based on changes in nitrile vibrational frequencies (ν(C≡N)). By coupling pulse radiolysis and time-resolved infrared spectroscopy (PR-TRIR), we measured ν(C≡N) IR bands of 30 para - and meta -substituted benzonitriles bearing C-, N-, and S-centered radicals. A linear scaling relationship was obtained between these experimental values and values obtained from DFT calculations. Using these computed values, two different Hammett constants, σ m , and σ p + , were determined for a series of C-, N-, O-, S-, Si-, and B-centered radicals. The differences between σm and σp+ values enable the separate evaluation of inductive and resonance effects in these open-shell substituents. The results suggest that there are three classes of radicals: one is electron withdrawing (σ m , σ p + > 0), one is electron donating (σm, σp+ < 0), and one is inductively withdrawing but resonance donating (σ m > 0, σ p + < 0). Our study represents a general approach to the analysis of the electronic properties of open-shell species and has potential applications in a wide range of molecular processes involving free radical intermediates.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Observation of a correlated free four-neutron system
A long-standing question in nuclear physics is whether chargeless nuclear systems can exist. To our knowledge, only neutron stars represent near-pure neutron systems, where neutrons are squeezed together by the gravitational force to very high densities. The experimental search for isolated multi-neutron systems has been an ongoing quest for several decades, with a particular focus on the four-neutron system called the tetraneutron, resulting in only a few indications of its existence so far, leaving the tetraneutron an elusive nuclear system for six decades. Here we report on the observation of a resonance-like structure near threshold in the four-neutron system that is consistent with a quasi-bound tetraneutron state existing for a very short time. The measured energy and width of this state provide a key benchmark for our understanding of the nuclear force. The use of an experimental approach based on a knockout reaction at large momentum transfer with a radioactive high-energy 8 He beam was key.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Photoacoustic methane gas analyser based on a 3.3-μm optical parametric oscillator
We demonstrate a bench-scale prototype of a photoacoustic (PA) methane gas analyser that takes advantage of an optical parametric oscillator (OPO) based on a fan-out MgO : PPLN structure and resonant differential PA detector. The OPO emits in a repetitively pulsed mode (∼1750 Hz) at an idler wavelength of ∼3.3 μm with an average power of ∼40 – 50 mW. Using the prototype laser PA gas analyser, we experimentally demonstrate the feasibility of measuring the background methane concentration in air (∼2 – 3 ppm of CH{sub 4}). The threshold sensitivity of the PA gas analyser (1σ) is determined to be ∼ 49 ppb of CH{sub 4}. (paper)
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Experimental and theoretical evidence for hydrogen doping in polymer solution-processed indium gallium oxide
The field-effect electron mobility of aqueous solution-processed indium gallium oxide (IGO) thin-film transistors (TFTs) is significantly enhanced by polyvinyl alcohol (PVA) addition to the precursor solution, a >70-fold increase to 7.9 cm 2 /Vs. To understand the origin of this remarkable phenomenon, microstructure, electronic structure, and charge transport of IGO:PVA film are investigated by a battery of experimental and theoretical techniques, including In K-edge and Ga K-edge extended X-ray absorption fine structure (EXAFS); resonant soft X-ray scattering (R-SoXS); ultraviolet photoelectron spectroscopy (UPS); Fourier transform-infrared (FT-IR) spectroscopy; time-of-flight secondary-ion mass spectrometry (ToF-SIMS); composition-/processing-dependent TFT properties; high-resolution solid-state 1 H, 71 Ga, and 115 In NMR spectroscopy; and discrete Fourier transform (DFT) analysis with ab initio molecular dynamics (MD) liquid-quench simulations. The 71 Ga{ 1 H} rotational-echo double-resonance (REDOR) NMR and other data indicate that PVA achieves optimal H doping with a Ga···H distance of ~3.4 Å and conversion from six- to four-coordinate Ga, which together suppress deep trap defect localization. This reduces metal-oxide polyhedral distortion, thereby increasing the electron mobility. Finally, hydroxyl polymer doping thus offers a pathway for efficient H doping in green solvent-processed metal oxide films and the promise of high-performance, ultra-stable metal oxide semiconductor electronics with simple binary compositions.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Localizing resonant magnetic perturbations for edge localized mode control in KSTAR
An external 3D magnetic perturbation typically drives a resonant response at the rational surfaces from the core to the edge of tokamak plasmas, due to strong mode coupling and amplification. In this paper, we present a method to isolate the edge from core resonant fields using the ideal perturbed equilibrium code and to design an edge-localized resonant magnetic perturbation (RMP) for effective edge localized mode (ELM) control. A robust feature of the edge-localized RMP is the curtailed response to the field at the low-field-side (LFS) midplane, as opposed to typical RMPs which strongly resonate with the LFS fields. This emphasizes the importance of off-midplane coils to improve ELM control without provoking a large core response that could lead to devastating instabilities. The conceptual design of new ELM control coils based on the edge-localized RMP in KSTAR shows how this new insight can be utilized to enhance the efficiency of our ELM suppression capabilities. Simple window-pane coils matching the edge-localized resonant mode structure substantially expand in the ELM suppression window beyond the existing coil. Further optimization using the flexible optimized coils using space-curves code leads to additional enhancement in the edge-localized control.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Resonance-enhanced x-ray multiple ionization of a polyatomic molecule
Extremely high charge states of atoms and molecules can be created when they are irradiated by intense x-ray pulses. At certain x-ray photon energies, electron ejection from atoms can be drastically enhanced by transient resonances created during the sequential ionization process. In this study we report on the observation of such resonance effects in a molecule, CH 3 I, and show the photon-energy-dependent shift of resonance-induced structures in ion charge state distributions. By comparing the ion charge state distribution of CH 3 I with that from ionization of atomic xenon, molecule-specific features are observed, which can be attributed to ultrafast intramolecular charge rearrangement. In addition, we experimentally demonstrate that the charge-rearrangement-enhanced x-ray ionization of molecules, previously found with hard x rays, also plays a role in the soft x-ray regime.
74 ATOMIC AND MOLECULAR PHYSICS↗
Resonant contributions to inclusive nucleon structure functions from exclusive meson electroproduction data
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Solving the one-dimensional penetration problem for the fission channel in the statistical Hauser-Feshbach theory
Here we solve the Schrödinger equation for an arbitrary one-dimensional potential energy to calculate the transmission coefficient in the fission channel of compound nucleus reactions. We incorporate the calculated transmission coefficients into the statistical Hauser-Feshbach model calculation for neutron-induced reactions on 235,238 U and 239 Pu. The one-dimensional model reproduces the evaluated fission cross section data reasonably well considering the limited number of model parameters involved. A resonance-like structure appears in the transmission coefficient for a double-humped fission barrier shape that includes an intermediate well, which is understood to be a quantum mechanical effect in the fission channel. The calculated fission cross sections for the neutron-induced reactions on 235,238 U and 239 Pu all exhibit a similar structure.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗