A comprehensive high-resolution spectral study of the ground vibrational state of triply deuterated methanol (CD3OH) using synchrotron radiation and backward wave oscillator-based spectrometer: Torsional energies and forbidden transitions.

High-resolution photoionisation and PFI-ZEKE photoelectron spectra of MgAr have been measured and used to characterise the rovibrational structure of the X + 2 Σ + ground electronic state of MgAr + and the photoionisation dynamics of MgAr. The Rydberg series and ionisation continua associated with the MgAr + X + ( v + = 0 − 7 , N + = 0 − 6 ) states were accessed from the a 3 Π 0 metastable state of MgAr via selected Λ-doublet components of the rotational levels of the Mg(3s3d)Ar 3 Π 0 excited electronic state in a resonant two-photon excitation sequence. The parity and rotational-state selection was exploited to identify the dominant autoionising Rydberg series in the photoionisation spectra and to characterise the partial-wave composition of the photoelectron in the PFI-ZEKE photoelectron spectra. Numerical evaluation of the cross-correlation of the observed photoionisation spectra with calculated spectra of unperturbed Rydberg series were used to determine cross-correlation ionisation-energy (CRIE) spectra with full resolution of the rotational structure, following a procedure introduced by Neuhauser, Siglow and Neusser [J. Chem. Phys. 106, 896 (1997)]. Combining the information contained in the PFI-ZEKE photoelectron spectra, the photoionisation spectra and the CRIE spectra provided an improved description of the rovibrational photoionisation dynamics of MgAr and of the level structure of the ground electronic state of MgAr + as well as accurate values of the corresponding ionisation energies.

C-H and C-D vibrations serve as versatile Raman probes for molecular detection and structural characterization, while site-specific vibrational analysis remains challenging due to overlapping modes and complex isotope effects. 1-Butanol (CH3CH2CH2CH2OH), a model small molecule with four distinct C-H moieties along its carbon chain, offers an ideal platform to decipher such complexity─yet the assignment of its gas-phase vibrational spectra (including Fermi resonances and site-dependent modes) has long been hindered by insufficient spectral resolution. Using a sensitive cavity-enhanced Raman instrument developed recently, we recorded high-resolution gas-phase Raman spectra of 1-butanol and two selectively deuterated isotopologues (CH3CD2CD2CD2OH and CD3CD2CD2CH2OH) in the ranges of 900-3100 cm-1, covering both C-H/C-D bending and stretching regions. By integration of quantum chemical calculations, isotope substitution, and polarization-dependent measurements, the spectral ambiguities were unraveled. Our analysis enables the assignments of all major spectral features, elucidating the role of symmetric and antisymmetric stretching vibrations and Fermi-resonant modes at each C-H site along the 1-butanol carbon chain. A systematic comparison of C-H versus C-D vibrational patterns allows us to quantify isotope-induced shifts in frequency and intensity. These findings not only advance fundamental understanding of 1-butanol's vibrational landscape but also provide a robust framework for site-specific Raman analysis of complex organic molecules and guide the design of Raman-based imaging probes for biological and environmental applications.

Nuclear magnetic resonance spectroscopy (NMR) plays a key role for the analysis of a plethora of molecules, including natural products and drug-like organic molecules. For such cases, 1H NMR spectra have proven imperative because of their high sensitivity and atomic resolution. However, these spectra are complicated by overlapped complex multiplet patterns. Here we show a deep-learning approach, which transforms spin-echo modulated 1H NMR spectra into highly sensitive and high-resolution singlet NMR spectra, that is, virtual homonuclear decoupled pure shift spectra. The approach was evaluated on experimental NMR spectra of complex organic compounds, where it outperforms current methods. The method also predicts uncertainties of the transformation and therefore allows for quantifications, which is a key strength of NMR. We believe that our approach will provide significant advantages when characterizing low-sensitivity samples and systems with exchangeable protons, where signals are not observed in traditional pure-shift spectra and substantial overlaps hamper analysis from conventional spectra.

Abstract Be stars are rapidly rotating B stars that have shown emission lines originating in a circumstellar disk. The mechanisms that lead to disk formation and dissipation are not known although progress has been made with some systems. We present a study of a disk outburst of the Be star λ Pavonis. Our data set comprises 698 high-resolution spectra contemporaneous with TESS photometry obtained in 2023. Near the end of the TESS monitoring, the star began disk building from a pristine diskless state. We find the disk was built within 5 days via the optical H i and He i lines, while the disk circularized in about 12 days. The disk began to decay in higher-excitation He i first, then at lower-excitation transitions, with the decay ending last for H α . We examine nonradial pulsations both through the TESS photometry and the line profile variations (LPVs) in the spectroscopy. Our analysis indicates that two periodicities seen in the TESS photometry (at 1.644 and 1.485 cycles day −1 ) are not seen in the spectral lines before, during, or after the outburst. The strongest photometric signal is a periodicity of 0.163 cycles day −1 , which appears as a difference between the two weaker signals and is visible in the spectra without any apparent changes in amplitude or phase. We additionally find evidence for fast nonphotometric pulsational variations over the course of spectroscopy obtained before, during, and after the outburst. These fast LPVs are strong, and interfere with the two weaker signals, hampering our ability to detect them via spectroscopy.

Abstract Doubly eclipsing quadruple systems provide an excellent opportunity to analyse multiple stellar systems and their evolutionary processes. However, their fundamental parameters are derived in only a few cases. We conduct new observations and study ten doubly eclipsing 2+2 candidates in the Northern sky. The new ground-based measurements are combined with TESS and archival data from available additional surveys (ASAS-SN, ZTF, and SuperWASP). We detrend and disentangle the light curves to derive precise minima timings. Further modelling is made using the PHOEBE 0.32 software package. Orbital period analysis using the O − C diagrams reveals seven candidates as newly confirmed quadruple systems. We identify ASASSN-V J020003.56+452605.2 as a blend of two independent binaries. The spectral analysis is carried out for ASASSN-V J233336.79+615012.0, and all four components and their radial velocities are measured from high-resolution spectra. Notably, 2MASS J04380244+5543535 is confirmed as a quadruple system with an additional detected cyclic O − C variations.

Detection of lung cancer cells via high-resolution near-infrared spectra of extracellular biofluids.

The spatial and kinematic structure of the circumgalactic medium remains poorly constrained observationally. We computed the clustering of C IV absorption systems at cosmic noon using quasar pairs. We analyzed VLT/UVES and Keck/HIRES high-resolution spectra ( R ≈ 45 000) of a sample of eight projected and four lensed quasar pairs that probe transverse separations, Δ r , from subkiloparsec to a few megaparsec over the redshift range 1.6 ≲ z ≲ 3.3. We detected and fit Voigt profiles to a total of 141 C IV systems, corresponding to 620 velocity components at all quasar lines of sight. We computed the two-point correlation function of C IV , ξ (Δ v , Δ r ), where Δ v is the velocity difference between components at all available scales. We found a strong dependence of ξ (Δ r ) on Δ r at all velocities. ξ (Δ r ) reaches a sharp peak at the smallest scales we analyzed, Δ r ≈ 0.1 kpc, decreases steadily up to Δ r ≈ 5 kpc, and remains flat up to Δ r ≈ 500 kpc, where it again begins to decrease. By fitting power laws to the projected transverse correlation function Ξ(Δ r ), we inferred two coherence lengths. The first is r 1 = 654 +100 −87 kpc, which we interpret as a representative size for the C IV enriched regions at z ≈ 2, and the second is r 2 = 4.70 +1.60 −1.19 kpc for the individual C IV -bearing clouds. When we instead projected this in Δ r , we found amplitudes of ξ (Δ v ) that were consistent with those in previous works that used quasars and extended background sources. Our results suggest that C IV might be a good tracer of not only the small internal structure of the circumgalactic medium, but also of the way in which galaxies cluster at cosmic noon.

Experimental determination of CO spectral line strengths and self-broadening coefficients at combustion-relevant temperatures.

Modeling and analysis of high-resolution H212CO spectra in the range 4450-5000 cm-1

Nuclear magnetic resonance (NMR) spectroscopy is an important analytical tool for probing molecular structures and interactions. For high complexity samples, multidimensional spectroscopy is essential for improving the resolution of NMR data. However, multidimensional experiments cost significant experimental time which scales with the number of indirect points. This is particularly challenging when dealing with highly dispersed nuclei, such as 13C, due to the large chemical shift range, with large regions that are spectrally empty. Herein, we describe a method for limiting the spectral width of dipolar based multidimensional NMR experiments in the indirect dimension in a manner that can be easily integrated into relaxation and distance measuring schemes. We demonstrate the acquisition of narrow strips of broadband homonuclear recoupling 13C-13C correlation spectra on a range of biomolecular and cellular samples, allowing targeted acquisition of high-resolution spectra of the region of interest with a significant reduction in the acquisition time. We also demonstrate the use of the spectral-band-selective method for allowing fast acquisition of RFDR build-up experiments. The band-selective method is easy to implement in any dipolar-based multidimensional pulse sequence by an addition of one pulse per band-selected indirect dimension and a slight modification of the phase cycle.

Abstract Wolf–Rayet (WR) winds exhibit variability driven by small-scale clumping and large-scale corotating interaction regions (CIRs), but their interplay remains uncertain. Archival high-resolution ESPaDOnS spectra of WR 6 were analyzed using wavelet decomposition to isolate variability on different scales. Time variance spectrum diagnostics confirm that clumping contributes 1% variability relative to line intensity, consistent with empirical trends for WR stars. Correlation analysis reveals strong coherence among He ii lines, while the N v λ 4945 and He i λ 5876 lines display weaker or shifted correlations, reflecting differences in their line-formation regions relative to He ii . Models in which CIRs locally suppress clumping demonstrate that if such interactions occur, spectroscopic diagnostics remain inconclusive. These results provide direct evidence that CIRs and clumping can coexist in WR winds.

Long-lived hot and dense plasmas generated by ultra-intense laser beams are of critical importance for laser-driven nuclear physics, bright hard X-ray sources, and laboratory astrophysics. We report the experimental observation of plasmas with nanosecond-scale lifetimes, near-solid density, and keV-level temperatures, produced by irradiating periodic arrays of composite nanowires with ultra-high-contrast relativistically intense femtosecond laser pulses. Jet-like plasma structures extending up to 1 mm from the nanowire surface were observed, emitting K-shell radiation from He-like Ti20+ ions. High-resolution X-ray spectra have been analyzed using 3D particle-in-cell (PIC) simulations of the laser–plasma interaction combined with collisional–radiative modeling (FLYCHK). The results indicate that the jets consist of plasma with densities of 1020–1022 cm−3 and keV-scale temperatures, persisting for several nanoseconds. We attribute the formation of these jets to the generation of kilotesla-scale global magnetic fields during the laser interaction, as predicted by PIC simulations. These fields may drive long-timescale current instabilities that sustain magnetic fields of several hundred tesla, sufficient to confine hot, dense plasma over nanosecond durations.

Abstract We present a catalog of 486 Ba stars identified in the GALAH DR4 survey using high-resolution spectra and precise abundance measurements. The sample was selected based on s- process enrichment criteria involving the abundances of Ba and La relative to Eu, and further refined using the signed-distance method, resulting in the largest sample of Ba stars to date, including five newly identified Ba dwarfs. Using astrometric and kinematic parameters from Gaia DR3 and StarHorse , we derived the Galactic velocity components for 367 Ba stars and found that most belong to the thin or thick disk, while 18 exhibit halo-like kinematics. Chemical abundance analysis suggests that most Ba stars are of in situ origin, whereas two stars (4077588766331013248 and 6692980582560946304) display signatures of accreted populations. The E – L z diagram further shows that star 4077588766331013248 lies within the region of substructure ED-8. The observed decline of [Ba/Fe] and [La/Fe] with increasing metallicity implies that s- process elements originate from nucleosynthetic sites distinct from those of iron-peak elements, while the decreasing [hs/ls] ratio toward higher metallicity indicates higher neutron-capture efficiency at lower metallicity. Both giant and dwarf Ba stars—except for 6053735173729807872—are confirmed binaries hosting white dwarf companions. Moreover, we estimated the masses of the former asymptotic giant branch (AGB) companions to these Ba stars based on the good agreement between the FRUITY AGB model predictions and their observed abundance patterns.

HelioSpectrotron 5000 (HS5000) is an interactive, multi-resolution solar spectral atlas designed to facilitate direct comparison between high-resolution reference spectra and observations obtained with a wide range of ground-based instruments. Based on the Hamburg FTS atlas, the HS5000 provides both absolute intensity and continuum-normalized spectra at arbitrary spectral ranges and resolutions, as well as curated line identifications and optional telluric contamination. This framework enables rapid wavelength calibration, line identification, and context image generation.

Abstract Problem: Breast MRI is recommended annually for high-risk individuals, typically using dynamic contrast-enhanced (DCE) MRI, which requires intravenous gadolinium. However, the added cost and invasiveness limit its use in average-risk populations. Developing a non-contrast MRI method would allow for expansion to broader screening. Diffusion-weighted imaging (DWI), a non-contrast technique, holds promise but suffers from low spatial resolution, limiting detection of small lesions. Restriction Spectrum Imaging (RSI), which uses multi-shell DWI, separates signal into restricted, hindered, free, and flow components without exogenous contrast, and has shown improved lesion characterization. This abstract presents a novel RSI model using multi-b-value input and high-resolution multi-band (MB) acquisition, achieving 2 mm isotropic resolution and improving small lesion detectability. Methods: Along with standard clinical DWI and DCE, high-resolution multi-shell (b-values (# of directions) 0 (1), 100 (6), 800 (6), 1500 (6), 3000 (12) s/mm2) DWI was collected using MB on 122 breast cancer and screening patients. RSI models follow a multi-exponential formula: S(b) = S0Σexp(-b*ADCi) = ΣCiexp(-b*ADCi). Tri- and tetra-exponential models (3C- and 4C-RSI) ADCi (fixed compartment apparent diffusion coefficients) were first calculated on large cancers (largest dimension > 2cm - 61 cancers). Ci signal contribution maps (C-maps) were estimated and provided spatial representation of each diffusion component. The products C1C2 and C2C3 were calculated as well. ADC maps from clinical DWI and DCE subtraction images (peak enhancement - pre-phase) were computed. To assess lesion conspicuity, contrast-to-noise ratios (CNR) were measured in C-maps on 28 lesions from a subset of 22 patients and compared to CNR from ADC and DCE. Finally, receiver operating characteristic (ROC) curves of each model and ADC were measured on the subset, separating malignant from benign lesions, by fitting a generalized linear model. Results: RSI models’ separation of diffusion contents are summarized on Table 1 . Regarding CNR, 3C-RSI showed highest values in C1C2 (median: 3.42, IQR: 2.66) and C2C3 (2.72, 1.72). For 4C-RSI, C1C2 (3.15, 3.42) and C2C3 (3.66, 3.79) were also highest. DCE had the highest (3.86, 1.45) and ADC the lowest (1.29, 0.49). Of the 28 test lesions (median lesion size: 2 cm, min: 5 mm, max: 7 cm - largest dimension), 7 were benign. ADC had an AUC of 0.78 while 3C- and 4C-RSI had an AUC of 0.87 and 0.96 respectively. DCE is considered 100% sensitive as selected lesions are based on DCE findings and had a specificity of 75% (7 lesions are benign), while at 80% sensitivity ADC, 3C- and 4C-RSI had a specificity of 50, 83 and 100%, respectively. Conclusion: RSI models achieved comparable CNR to DCE, outperforming ADC. They also had the highest AUCs and specificities, highlighting RSI as a potential non-contrast method for early detection. Citation Format: S. Loubrie, J. Lim, S. Batasin, H. J. Yu, J. Zou, S. Ebrahimi, C. C. Conlin, A. Guidon, T. M. Seibert, A. M. Dale, A. Wallace, H. Ojeda-Fournier, A. E. Rodriguez-Soto, R. Rakow-Penner. Non-contrast detection of breast cancer using high-resolution restriction spectrum imaging [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-06-07.

We propose a two-level theory that connects Lin-equation-based dynamical coarse-graining of the turbulence cascade with an information-theoretic selection principle in logarithmic wavenumber space. This framework places the dissipation-range spectral shape on a verifiable logical basis rather than on ad hoc fitting. At the first (dynamical) level, we formulate an autonomous conservative Fokker–Planck equation for the normalized density and probability current. Under sufficient boundary decay and a strictly positive effective diffusion, the sign-reversed Kullback–Leibler divergence is shown to be a Lyapunov functional, yielding a rigorous H-theorem and fixing the arrow of time in scale space. At the second (selection) level, the dissipation range is treated as a stationary boundary-value problem for an open system by introducing a killing term for an unnormalized scale density. A WKB (Liouville–Green) analysis restricts the admissible tail to a stretched-exponential form and links the tail exponent to the high-wavenumber scaling of the effective diffusion. The exponential prefactor is fixed by dissipation-rate consistency, and the remaining degree of freedom is determined by one-dimensional Kullback–Leibler minimization (Hyper-MaxEnt) against a globally constructed reference distribution. The resulting exponent range is validated against the high-resolution DNS spectra reported in the literature.

In this paper, we demonstrate that neighboring transition effects (NTEs) enhance the dressed four-wave mixing (FWM) in a ladder-type atomic system with hyperfine (hf) states. By comparing FWM signals in red- and blue- detuned regimes, we confirm that the enhancement and asymmetry of signals are governed by three key factors: NTE from collective contributions of EIT-mediated coherence and pure two-photon absorption (TPA) across multiple hf channels, transition probabilities of hf pathways and the neighboring-state openness modulating decay efficiency. Dressed-state analysis and theoretical calculations validate this mechanism. Furthermore, high-resolution spectra enable precision metrology of excited-state energy gaps (e.g., 17[Formula: see text]MHz resolution), advancing quantum light source design.

Abstract We introduce a new photometric catalog of RR Lyrae (RRL) variables (∼300,000) mainly based on data available in public datasets. We also present the largest and most homogeneous spectroscopic dataset of RRLs and blue horizontal branch (BHB) stars ever collected. This includes radial velocity measurements (∼16,000) and iron abundances (Δ S method for 8140 RRLs, plus 547 from literature). Elemental abundances based on high-resolution spectra are provided for 487 RRLs and 64 BHB stars. We identified candidate RRLs associated with the main Galactic components and their iron distribution function (IDF) becomes more metal rich when moving from the halo ([Fe/H] = −1.56) to the thick disk (TCD; [Fe/H] = −1.47) and thin disk (TND; [Fe/H] = −0.73). Furthermore, halo RRLs and RRLs in retrograde orbits are α enhanced ([ α /Fe]=0.27, σ = 0.18), while TCD RRLs are either α enhanced ([Fe/H] ≤ −1.0) or α poor ([Fe/H] > −1.0), and TND RRLs are mainly α poor ([ α /Fe] = −0.01, σ = 0.20). We also identified RRLs associated with the main stellar streams—Gaia–Sausage–Enceladus (GSE); Sequoia, Helmi, and Sagittarius—and we found that their IDFs are quite similar to halo RRLs. However, GSE RRLs lack the metal-poor/metal-rich tails and their α -element distribution is quite compact. The iron radial gradient in Galactocentric distance for TND, TCD, and halo RRLs is negative and it decreases from −0.026, to −0.010, and to −0.002 dex kpc −1 . The iron radial gradient based on dry halo (halo without substructures) RRLs is, within the errors, equal to the global halo. We also found a strong similarity between iron and [ α /Fe] radial gradients of Milky Way RRLs and M31 globular clusters throughout the full range of galactocentric distances covered by the two samples.

Context . To determine stellar luminosities and radii, it is necessary to know the total bolometric fluxes emitted by stars - or equivalently their bolometric corrections (BCs) - as accurately as possible. Aims . The aim of this paper is to present and describe a new database of synthetic stellar magnitudes and BCs for 752 filters from 78 ground- and space-based instruments calculated using the most recent version of the BOSZ synthetic stellar spectral library. Methods . From the entire grid of BOSZ theoretical spectra, our synthetic magnitudes in the Vega magnitude system were determined using the corresponding species Python routines. Results . The database spans effective temperatures from 2800 to 16 000 K, log g from −0.5 to 5.5, metallicities from −2.5 to 0.75, [α/M] from −0.25 to 0.5, [C/M] from −0.75 to 0.5, and reddening up to A V = 3.1 mag. Using high-resolution (R = 50 000) synthetic spectra allowed us to precisely track the effects of abundances on stellar BCs and luminosities. Conclusions . By applying the new BCs to 192 000 APOGEE stars, we calculated luminosities and demonstrated that neglecting carbon can introduce up to ±0.2% errors in luminosity. The new Gothard Observatory Synthetic Stellar Photometry Database may enable more accurate fundamental parameter determinations for large stellar samples using a vast amount of past, present, and upcoming surveys, such as Gaia, LSST, and the Roman Space Telescope.