Abstract In this article, we investigate the propagation of electromagnetic waves (EW) within a different type of transmission line, combining a theoretical analysis based on the Transfer Matrix Method (TMM) and a numerical study based on the Finite Element Method (FEM). The proposed structure is composed of a segment filled with a right-handed material (RHM,〖 ε〗_1> 0 and 〖 μ〗_1> 0), coupled to a closed lateral transmission line resonator filled with a metamaterial ENG, RHM or an absorber with effective permittivity (ε_2 (f) and 〖 μ〗_2> 0). The transmission line resonator is modeled as a microwave circuit with lumped elements, including a series capacitor (C), a shunt inductor (L), and a resistor (R). The results demonstrate that adjusting the resonator length and its electrical parameters allows multiple transmission bands over a wide frequency range (up to 10 GHz), while finely controlling the reflection and absorption characteristics, resulting in very narrow resonance modes. These features make the proposed structure suitable as an integrated gigahertz selective filter for optimized filtering in advanced signal processing, telecommunications, radar, and satellite applications.

Optical metasurfaces supporting resonances with high quality factors offer an outstanding platform for applications such as nonlinear optics, light guiding, lasing, sensing, light-matter coupling, and quantum optics. However, their experimental realization typically demands elaborate multistep procedures such as metal or dielectric deposition, lift-off, and reactive ion etching. As a consequence, accessibility, large-scale production, and sustainability are constrained by reliance on cost-, time-, and labor-intensive facilities. We overcome this fabrication hurdle by repurposing poly(methyl methacrylate), which is usually employed as a temporary resist, as the resonator material, thereby eliminating all steps except for spin-coating, exposure, and development. Because the low refractive index of the polymer limits effective mode formation, we present a bilayer recipe that enables the convenient fabrication of a freestanding membrane to maximize the index contrast with its surroundings. Since etching induced defects are circumvented, the membrane features high quality nanopatterns. We further examine the suspended membrane with scanning electron microscopy and extract its position-dependent spring constant and pretension with nanoindentation experiments applied with the tip of an atomic force microscope. Our all-polymer metasurface hosting bound states in the continuum experimentally delivers high quality factors (up to 523) at visible and near-infrared wavelengths, despite the low refractive index of the polymer, and enables straightforward geometry-based tuning of both line width and resonance position. We envision this methodology to facilitate accessible, high performance metasurfaces with specialized use cases such as material blending, angled writing, and mechanically based resonance tuning.

The resonance lines of the 1H and 13C liquid NMR spectra of the linear peptide antibiotic gramicidin A were assigned by performing various 2D NMR experiments such as 2D 1H–13C HSQC, 2D 1H–15N HSQC, 1H–13C HMBC, 1H–1H COSY, and 1H–1H TOCSY. The spatial proximity among various protons and inter-nuclear distances were determined by a 2D 1H–1H NOESY NMR experiment. The detailed structure and nuclear spin dynamics of this peptide antibiotic were also determined by extracting the principal components of CSA (chemical shift anisotropy) parameters and spin-lattice relaxation times at the various 13C nuclear sites by applying advanced solid-state NMR methodologies. The CSA parameters were determined by employing a 13C 2DPASS CP-MAS SSNMR experiment; the site-specific spin-lattice relaxation time was determined by a method designed by Torchia, and the spatial proximity between 1H and 13C nuclei was determined by a 1H–13C PMLG HETCOR experiment. A higher degree of freedom was observed within this linear polypeptide by the spin-lattice relaxation measurements, which can be considered the origin of its antibacterial activity. The principal components of the CSA-parameters are substantially higher for the carbon-13 nuclei residing on the indole ring of the l-tryptophan amino acid residue due to magnetic shielding and deshielding effects and also due to the presence of intramolecular and intermolecular hydrogen bonds. Notably, 13C nuclei in the indole rings of l-tryptophan residues exhibited significantly larger values of the principal components of CSA parameters and longer spin-lattice relaxation times. These types of detailed analysis of the structure and dynamics of peptide antibiotics will augment the field of ‘NMR crystallography’ and will also serve as a foundation for formulating a new class of antimicrobial peptides.

We present X-shooter spectroscopic and photometric observations of a sample of 21 hydrogen-poor superluminous supernovae (SLSNe-I), spanning a redshift range of z = 0.13-0.95, aimed at searching for shells of circumstellar material (CSM). Specifically, we focused on identifying broad absorption features that are blueshifted by several thousand kilometers per second relative to the narrow absorption lines associated with the host galaxy. These broad features have previously been interpreted to arise from resonance line scattering of the SLSN continuum by rapidly expanding CSM ejected shortly before explosion. Utilizing high-quality near-ultraviolet spectra, we modeled the region around 2800 Å to characterize the Mg II Mg II line profiles, enabling us to either confirm their presence or place constraints on undetected CSM shells. We identified five objects in our sample that show broad absorption features consistent with the presence of CSM. While SN,2018ibb, SN,2020xga, and SN,2022xgc have been previously reported, we identified previously undiscovered CSM shells in DES15S2nr and DES16C3ggu. In the case of DES15S2nr, the CSM shell is located at ∼ 3.4 Mg II 10^ 15 ̊m cm and is moving with a maximum velocity of ∼ 4800̊m km s^ -1 . For DES16C3ggu, the shell lies at ∼ 4.8 ̊m cm and reaches up to ∼ 4700 ̊m km s^ 10^ 15 -1 . These shells were likely expelled approximately two and three months before the explosion of their respective associated SNe on timescales consistent with late-stage eruptive mass-loss episodes. We further found evidence that the velocities of the CSM shells in all objects lie within 3000-5000 ̊m km s^ -1 , which may reflect an intrinsic property and could hint at a similar mass-ejection mechanism. We did not find any correlations between the shell properties and the SN properties, except for a marginal correlation between the light curve decline timescale and the shell velocities. This correlation needs further work; however, if it applies, it is a powerful link between the late-time mass ejection and eventual explosion. We further demonstrate that CSM configurations similar to the majority of the detected shells would have been observable in spectra with a signal-to-noise $>5$ per resolution element, and that the lines from a shell are, in general, detectable except in cases where the shell is either very geometrically and/or optically thin. Therefore, we conclude that the non-detections are unlikely to arise from selection effects but they may instead point to the existence of a subclass of SLSN-I progenitors undergoing late-stage shell ejections shortly before explosion.

Photopumping of K/Xe vapor mixtures over a continuous spectral region >1.2 THz (>40 cm-1) in breadth yields lasing on the D1 line of atomic potassium (4p2P1/2 → 4s2S1/2) by populating the dissociative B2Σ1/2+ or weakly bound A2Π3/2 states of the KXe excimer molecule. Subsequent dissociation of the excited molecule populates the 4p2P3/2 and 4p2P1/2 levels of the K atom, the latter of which is the upper level for the 769.9 nm resonance line laser. Lasing over ∼60% of the 57.7 cm-1 gap lying between the spin-orbit split 4p2P3/2 - 4p2P1/2 states has been achieved, and single-pulse energies up to ∼35 µJ have been obtained when pumping the K/Xe mixture in the vicinity of the D2 line (766.5 nm) in a single-pass pumping configuration of the resonator. The quantum efficiency (>99%) and broad pump-acceptance bandwidth afforded by the KXe excimer lend this hybrid atomic/molecular photodissociation laser to pumping with free-running semiconductor laser arrays.

Rational catalyst design remains a significant challenge, with electronic structure, steric, and electrostatic effects known to contribute to activity. Recently, dynamics has been recognized as another factor that impacts catalysis, though identifying and predicting these effects have remained out of reach. Nickel-substituted rubredoxin (NiRd), a protein-based mimic of a hydrogenase enzyme, serves as a model catalytic system in which dynamics can be systematically investigated with respect to activity. While over 30 secondary-sphere mutants of NiRd have been shown to be catalytically active, no significant correlation has been observed between the rates and catalytic overpotential or electronic structure, prompting questions about the protein-derived factors that modulate activity. In this work, NMR spectroscopy was used to investigate the roles of substrate accessibility, protein dynamics, and protein stability in controlling catalysis. Significant paramagnetic effects from the nickel center (S = 1) isolate the methylene proton resonances of the metal-coordinating cysteine residues. The sensitivity of resonance positions and line widths to local environment offers an opportunity to study dynamic molecular changes around the metal center with high resolution. Machine learning algorithms were employed to identify correlations between the catalytic activity and the paramagnetic NMR spectra. These analyses revealed spectroscopic features of specific cysteine protons that report on catalytic overpotential and increased turnover rates, which are further supported by the results obtained using high-field NMR techniques. Collectively, these studies indicate the potential for multifrequency NMR techniques to resolve key contributors to catalytic activity and highlight the importance of local and outer-sphere dynamics.

Abstract Resonance lines encode rich information about astrophysical sources and their environments, yet fully analytic treatments of multi-line radiative transfer remain almost entirely unexplored. We present exact, closed-form solutions for steady-state resonant-line radiativeP transfer in “V-shaped” atomic networks, where a single ground state couples to multiple transitions. Starting from the full angle-dependent transfer equation, we generalise absorption and emission coefficients to an arbitrary number of lines, derive a modified Fokker–Planck expansion of the frequency-redistribution integral, and use a judicious change of variables to reduce the problem to a Helmholtz equation with point-like sources in frequency space. This transformation admits analytic solutions for arbitrary sets of lines with fixed frequency offsets and strengths in both slab and spherical geometries. We implement V-shaped line networks in the colt Monte Carlo radiative transfer code and find excellent agreement with the analytic predictions across a wide range of line separations, optical depths, and damping parameters, establishing our solutions as stringent validation benchmarks. For concrete applications related to the Lyman-alpha (Ly $\alpha$ ) transition of neutral hydrogen, we examine how fine-structure splitting and deuterium injection modify the emergent spectra, internal radiation field, and radiative force multiplier. We show that these effects leave previous conclusions about Ly $\alpha$ feedback in the early universe essentially unchanged. Even when direct observational diagnostics are subtle, our framework provides novel analytic and numerical insights into coupled resonance-line transport and facilitates progress in general modelling of multi-line radiative transfer in diverse astrophysical settings.

The article discusses an original spectroscopic method for the study of supersonic argon jets in atomic and cluster flow regimes. The method is based on absolute measurements of the VUV radiation flux from a supersonic argon jet induced by a 1 keV electron beam. The integral radiation flux and spectral distribution of the radiation flux density of a supersonic argon jet in the range of 50–150 nanometers were measured, which made it possible to determine the density of the non-condensed atomic component, the fraction of condensate, and the density of clusters in a supersonic argon jet at given parameters of its flow into vacuum. The obtained parameters also allowed us to estimate the emission cross sections for the argon resonance lines Ar I (λ = 104.8 nm, λ = 106.7 nm) and the cluster continuum λ = 127 nm.

Abstract We present observations from the Van Allen Probes of lower band chorus waves interacting with wavelength‐scale density irregularities and gradients on the order of a few kilometers—comparable to the wavelength of the chorus waves themselves. High‐resolution electron density is derived from the upper hybrid resonance line in the High‐Frequency Receiver (HFR) merged spectrum, with a time resolution of 0.5 s. These observations show that density fluctuations modulate both the amplitude and wave normal angles of lower band chorus. High‐amplitude, quasi‐parallel waves are associated with regions of enhanced density, whereas very oblique waves with lower amplitude are found in regions of density depletion. The very oblique chorus waves are not generated locally by anisotropic electrons or shaped solely by propagation effects. One‐dimensional wave field calculations in a multilayered plasma demonstrate that wavelength‐scale density irregularities can scatter incident quasi‐parallel waves and produce very oblique waves at density depletions.

Abstract Interplanetary shocks compress the magnetosphere and launch fast‐mode waves propagating in the inner magnetosphere, which can excite field line resonance in the ultra‐low frequency (ULF) range. The resulting phase delay due to wave propagation between two observation points manifests observationally as a phase difference, which is commonly used to calculate the azimuthal wavenumber. In this paper, we suggest this wavenumber to be named as effective azimuthal mode number ( m *) to distinguish it from the azimuthal mode number derived from solving the MHD wave equation in a dipole magnetic field, which is ∼0 for the toroidal component and infinite for the poloidal component. Utilizing magnetic field measurements from Geostationary Operational Environmental Satellites after interplanetary shocks spanning from January 2011 to March 2024, we perform a statistical analysis of shock‐induced ULF wave characteristics based on cross‐wavelet analysis. Our results for dayside events reveal that the magnitude of m *‐values derived from observations, denoted as , for compressional, poloidal and toroidal components are predominantly less than 3. All three wave components are characterized by anti‐sunward propagation. The ‐values for the two transverse components are slightly higher than that for the compressional component. These signatures are consistent with the theory proposed in this study, providing a generalized estimation of the m *‐value of shock‐induced ULF waves for the analysis of radial diffusion coefficients in the radiation belts.

Abstract Ultra‐low frequency (ULF) waves are a ubiquitous carrier of energy in geospace. However, their efficiency in transferring solar wind energy into the upper atmosphere remains a fundamental and not well‐understood question. This is due to their global presence, which cannot be fully quantified by spatially limited observations, and the need for self‐consistent global modeling to account for their dependence on dynamic, inhomogeneous magnetic fields and plasma densities. In this study we use a purely global magnetohydrodynamic model to investigate energy inputs to the ionosphere in the form of Poynting flux. Oscillations in solar wind dynamic pressure excite field line resonances in the magnetosphere. The total Alfvénic Poynting flux entering the ionosphere can be comparable to the total quasi‐steady Poynting flux under northward interplanetary magnetic field. The efficiency of this energy transfer via ULF waves depends on the driving frequency of the solar wind and the ionospheric Pedersen conductance.

This paper discusses the application of on-chip terahertz (THz) filters attached to waveguides that can act as sensor elements, including for scanned imaging applications. Our work presents a comparative numerical study of several different geometries (comprising five split-ring resonator geometries and a quarter-wavelength stub resonator, the latter being well established as a sensor at THz frequencies and therefore able to act as a benchmark). We designed each structure to have a resonant frequency of 500 GHz, allowing the impact of resonator geometry on sensing performance to be isolated; the performance was quantified by assessing each design using four figures of merit: resonance quality factor, sensitivity (relative frequency shift under dielectric loading), responsivity (sensitivity weighted by resonance sharpness), and the electric field confinement area. Simulations were conducted using Ansys HFSS using the properties of a commercially available photoresist (Shipley 1813) as a dielectric load to assess performance under conditions comparable to previous experimental studies. The analysis showed that while sensitivity remained broadly similar across geometries, responsivity and quality factor differed substantially between resonators. Furthermore, the spatial distribution of the electric field and current density, particularly in rotated configurations, was found to significantly impact coupling efficiency between the resonator and transmission line. Our findings provide guidance for the general design of systems employing THz sensors while establishing a framework with which to benchmark future sensor geometries.

Due to unique electromagnetic and magneto-optical properties, iron- yttrium garnet (Y 3 Fe 5 O 12 , YIG) and its solid solutions are used in the production of film structures for a new field of spin electronics, known as magnonics. It is essential to control the chemical composition of synthesized YIG, including both primary (Fe, Y) and trace elements (Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th, U), because the presence of impurities above 10 –2 wt.% significantly broadens the ferromagnetic resonance line of the films and deteriorates the properties of the film structures. It is shown that the use of two methods, atomic emission (ICP AES) and mass spectrometry with inductively coupled plasma (ICP MS), under selected conditions of analysis, allows for the accuracy of its results and a wide range of detectable elements. The peculiarities of the synthesis of YIG film structures on a gallium arsenide substrate using a novel none-epitaxial method proposed by the authors have been studied. The effect of YIG impurity composition on the structure and properties of the resulting films is shown. To prevent the interaction between Y 3 Fe 5 O 12 and GaAs at the interface during film crystallization, a barrier layer of aluminum oxide was pre-sprayed onto the substrate. The ferromagnetic resonance spectra of Y 3 Fe 5 O 12 /AlOx/GaAs films obtained by various methods have been studied. It was found that the width of the FMR line for films obtained by spraying YIG single crystals is 30 – 40 Oe less than for films contained impurity elements.

In this study, we investigate a compact double-resonance scalar magnetometer employing a single detuned elliptically polarized laser beam. A multipass cavity is incorporated to enhance the Faraday rotation signal. We observe asymmetric atomic response line shapes and resonance frequency shifts under non-collimated beam propagation through the vapor cell, and attribute these effects to light shifts. Experimental measurements of these light-shift effects are presented and show agreements with numerical simulations. Moreover, we demonstrate that this light shift can be significantly suppressed using a compensation method developed in our earlier work.

Abstract Observations of the planet-hosting star WASP-12 show a distinctive depression in the Mg ii and Ca ii resonance lines. This has been interpreted as a marker of atmospheric loss from the close-in hot Jupiter WASP-12b and the resulting formation of a gas torus around the star. In this paper we quantify the Mg ii absorption from this torus, compared to that provided by the stellar wind, the stellar astrosphere and the ISM. To do this we piece together the full density profile of Mg ii from WASP-12 to an observer on Earth using a combination of hydrodynamical simulations and observations. We find that the bulk of the gas along the line of sight is contained within a dense torus close to WASP-12. However, the temperatures in this torus are sufficient to promote Mg into a doubly (Mg iii) or higher ionized state. As a result, the singly ionized fraction (Mg ii) is low. We find that most of the Mg ii is not in the torus but in the ISM. Despite this, the total column density of Mg ii is two orders of magnitude lower than required to explain observations of the system. To resolve this discrepancy, we note that the torus gas is at a temperature where it will cool efficiently. We speculate that the onset of the cooling instability will cause the torus to fragment, forming cold clumps with a higher fraction of Mg ii, capable of explaining the observed absorption.

Abstract The ubiquity and relative ease of discovery make 2 ≲ z ≲ 5 Ly α emitting galaxies (LAEs) ideal tracers for large-scale structure of the distant Universe. In addition, because Ly α is a resonance line, but frequently observed at large equivalent width, it is potentially a probe of galaxy evolution. The LAE Ly α luminosity function (LF) is an essential measurement for making progress on both of these topics. Although several studies have computed the LAE LF, very few have delved into how the function varies with environment. The large area and depth of the One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN) survey makes such measurements possible at the cosmic noon redshifts of z ∼ 2.4, 3.1, and 4.5. In this initial work, we present algorithms needed to rigorously compute the LAE LF, and test them on the ∼16,000 ODIN LAEs found in the extended COSMOS field. Using these limited samples, we find weak evidence that protocluster environments suppress the numbers of faint LAEs compared to the field. We also find that the LF decreases in number density and evolves towards a steeper faint-end slope over cosmic time from z ∼ 4.5 to z ∼ 2.4.

In 2016, x-ray microcalorimeter spectroscopy with the Hitomi soft x-ray spectrometer observed strong spectrum lines of Fe XXIV-XXVI in galaxy NGC 1275 at the center of the Perseus cluster of galaxies. Special attention was paid to the Kα lines of the Fe plasmas [Aharonian etal., Nature (London) 535, 117 (2016)0028-083610.1038/nature18627]. The dominant spectral component was treated as a collisional ionization equilibrium plasma using the SPEX code. However, it was found that the ratio of Fe XXV Heα resonant and forbidden lines is lower than the observed one. This difference could be attributed to the insufficient consideration of radiation field effects in the spectral modeling approach. To address this issue, we recalculated the emission spectra under astrophysical conditions using the nonlocal thermodynamic equilibrium collisional-radiative code. Our analysis reveals a pronounced sensitivity of the emission spectra to the radiative temperature and distribution. Furthermore, we performed a detailed investigation of the atomic processes involving photon interactions and their effects on the emission spectra of Fe plasmas. The recalculated spectra show excellent agreement with the measured spectra, highlighting the significant role of the radiation field in shaping the spectral characteristics of astrophysical plasmas.

Abstract Radiation pressure on spectral lines is a promising mechanism for powering disc winds from accreting white dwarfs (AWDs) and active galactic nuclei (AGN). However, in radiation-hydrodynamic simulations, overionization reduces line opacity and quenches the line force, which suppresses outflows. Here, we show that small-scale clumping can resolve this problem. Adopting the microclumping approximation, our new simulations demonstrate that even modest volume filling factors (fV ∼ 0.1–0.01) can dramatically increase the wind mass-loss rate by lowering its ionization state—raising $\dot{M}_{\rm wind}$ and yielding $\dot{M}_{\rm wind}/\dot{M}_{\rm acc}\!\gtrsim \!10^{-4}$ for such modest filling factors. Clumpy wind models produce the UV resonance lines that are absent from smooth wind models. They can also reprocess a significant fraction of the disc luminosity and thus dramatically modify the broad-band optical/UV SED. Given that theory and observations indicate that disc winds are intrinsically inhomogeneous, clumping offers a physically motivated solution. Together, these results provide the first robust, self-consistent demonstration that clumping can reconcile line-driven wind theory with observations across AWDs and AGNs.

Polarized electron spins in photoexcited triplet states enable dynamic nuclear polarization (DNP) to enhance magnetic resonance imaging (MRI) sensitivity. For a practical nuclear polarization of 10%, single crystals must be precisely oriented in a magnetic field to generate narrow electron spin resonance lines, which is not appropriate for actual medical applications. Here, substituted fullerenes as triplet polarizing agents enable 1H polarizations above 10%, even for random molecular orientations. While they have not been used as polarizing agents for triplet-DNP because of electron spin relaxation via pseudo-rotation, we overcome this by chemical modification of two sites on C60 fullerenes. Symmetry considerations reveal fullerenes that avoided pseudo-rotations. Di-substituted fullerenes are ideal polarizing agents with sharp linewidths and long relaxation times that enabled 14.2% 1H polarization in randomly oriented orientations. Optimized polarizing agents represent a promising approach for ultra-sensitive MRI medical diagnostics without the need for DNP under cryogenic temperatures and severe orientation control.

Aims . We present a spectroscopic analysis of ten carbon-enhanced metal-poor (CEMP) stars of type CEMP-s and CEMP-rs and determine their non-local thermodynamic equilibrium abundances of Ba and Eu, as well as the fractions of the odd Ba isotopes (F odd ). The determination of F odd in stars provides unambiguous information about the s-process contribution to their total Ba abundance. We aim to obtain observational constraints on the enrichment scenarios of CEMP-rs stars. Methods . The Ba abundances inferred from the resonance Ba II 4554 and 4934 Å lines depend on the adopted Ba isotope mixture. We took different F odd from 0.1 to 1.0 and determined the corresponding abundances from the Ba II resonance lines in each sample star. In addition, we determined the Ba abundances from the Ba II subordinate lines, which are almost independent of F odd . We then compared the Ba abundances derived from the subordinate lines with those from the Ba II resonance lines. Results . We found different F odd values in CEMP-s and CEMP-rs stars. CEMP-s stars exhibit F odd = 0.05 −0.03 +0.07 , 0.17 −0.14 +0.63 , 0.19 −0.14 +0.50 , and 0.19 −0.12 +0.33 . The obtained values agree within the error bars with the s-process F odd = 0.10 and the solar F odd = 0.18. Although the uncertainties are large, the possibility of a Ba isotope origin in a pure r-process with F odd = 0.75 can be excluded for three of the four stars. CEMP-rs stars show F odd = 0.34 −0.21 +0.55 , 0.36 −0.14 +0.23 , 0.44 −0.22 +0.43 , 0.53 −0.38 +0.47 , and 0.57 −0.31 +0.43 , which are higher than those in CEMP-s stars. Although the uncertainties are large, in four of five stars, the possibility of a pure s-process origin for the Ba isotopes can be excluded. The obtained values agree within the error bars with the predicted i-process F odd = 0.6 to 0.8. Conclusions . Our analysis of CEMP-rs stars with [Ba/Eu] > 0 demonstrates that their [Ba/Eu] and F odd cannot be jointly explained by a mixture of material produced by the r- and s-processes. The obtained results argue that the i-process causes the chemical composition of these CEMP-rs stars.