Raman spectroscopy as the quantum eye to reveal molecular dynamics in biology.

Frequent load fluctuations from renewable-energy integration increase operational stress on steam turbo-generators and raise the risk of rotor inter-turn short circuits. This paper proposes a measurement-oriented multimodal framework for robust fault-state estimation under complex operating conditions. A fault-sensitive measurand derived from 50 Hz and 100 Hz vibration components at the stator excitation end, is defined and theoretically linked to rotor winding faults. An electromagnetic-mechanical coupled model in ANSYS reveals how rotor inter-turn faults modulate stator vibration spectra; modal characteristics are validated on a 600 MW turbo-generator. A formal measurement model maps the chain from vibration sensing and speed-reference acquisition to feature transformation and fault-state estimation. Variational mode decomposition parameters are optimized via the arithmetic optimization algorithm; band-pass amplitude sequences yield multimodal time-frequency features, processed by a multimodal feature-enhanced temporal neural network. Traceability from transducer to processed feature is ensured, and uncertainty is quantified across signal-to-noise ratio variation, frequency resolution, modal separation, repeatability/reproducibility, and confidence intervals of estimates. Under test conditions, the method achieves robust fault-state estimation and superior noise immunity versus baseline models, demonstrating strong potential for practical rotor winding fault diagnosis in large turbo-generators. • A measurement-oriented framework for rotor winding fault-state estimation. • Fault-sensitive modal signatures are extracted from non-stationary vibrations. • Optimized VMD improves separation of fault-related vibration components. • Multi-physics simulation validates spectra under inter-turn short circuit. • A lightweight temporal network enables robust estimation under noise.

Synthesis of silver nanoparticles using Nymphaea nouchali-derived 9-Octadecenal: Antimicrobial, antidiabetic properties and in Silico ADMET insight

Diagnosis of Systemic Lupus Erythematosus (SLE) and Lupus Nephritis (LN) based on a Raman-Metabolomics multimodal re-annotated segment hierarchical fusion model.

ABSTRACT Early diagnosis of cancer is crucial for improving survival rates and treatment outcomes. However, conventional diagnostic methods, such as tissue biopsy and imaging, often involve invasive procedures and may require extended processing times. In recent years, noninvasive biomarker detection techniques, such as Raman spectroscopy and infrared (IR) spectroscopy, have been widely applied in cancer diagnosis. Nevertheless, spectral data obtained from different modalities are frequently affected by factors such as sampling frequency, noise, and acquisition conditions, making data alignment and fusion increasingly challenging. To enhance the accuracy of multi‐class cancer biomarker identification, this paper proposes a multimodal intelligent recognition model based on the combined analysis of Raman and IR spectroscopy. The model first aligns the spectral data from different modalities using the synchronous dynamic time warping (SDTW) algorithm to eliminate frequency shifts. Then, we apply fast Fourier transform (FFT) to extract frequency–domain features, capturing key information from the spectra. Finally, a dynamic convolution module (DynamicConv1d) is introduced, which adaptively generates convolutional kernels through a learning mechanism. This allows for customized feature extraction tailored to different spectral samples, effectively enhancing feature discriminability. The model fuses information from both average pooling and max pooling to highlight important channels related to molecular vibrations while suppressing noise interference. In the feature fusion stage, a dynamic feature fusion module is constructed. It employs an attention mechanism to perform a weighted integration of Raman and IR features, fully leveraging the complementarity between the two modalities. Experimental results demonstrate that the proposed method achieves superior multi‐class performance on several cancer spectral datasets. It can not only diagnose the presence of cancer but also differentiate between specific types, significantly improving the model's generalization ability and diagnostic reliability. This study provides new ideas and methodological support for the application of multimodal spectroscopic techniques in early disease screening and biomarker detection. The experimental results show that the model achieves an accuracy of 98.55% and an AUC of 0.9900. It also outperforms traditional single‐modality models across multiple evaluation metrics and has strong potential for clinical application.

Water-soluble functionalized fullerenes commonly referred to as fullerenols, fullerols or polyhydroxy fullerenes are widely used in photonics, catalysis, and biomedicine, yet their molecular structures have been assumed to consist solely of hydroxyl groups for nearly three decades. This assumption remains despite persistent mismatches between calculated and experimental vibrational and optical spectra as well as expected and observed chemical reactivity. Here we combine Fourier transform infrared (FTIR) and absorption (UV-Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), targeted chemical derivatization, and computational quantum chemistry to resolve this discrepancy. We show that only a polyoxy-fullerene architecture incorporating counterion-coordinated carbonyl and hemiketal groups alongside hydroxyls reproduces both the characteristic FTIR features and the experimental UV-Vis absorption profile. Apurely hydroxylated fullerene model fails to capture the dominant FTIR band and asymmetric ultraviolet absorption. Oxime-formation experiments chemically validate the presence of carbonyl and hemiketal groups. This structural reassignment resolves long-standing inconsistencies in fullerene chemistry, corrects a pervasive misinterpretation in the literature, and establishes a framework for rationally tuning the optical and chemical properties of functionalized nanocarbons.

An experimental study is conducted of the fluid-thermal-structural interaction of a clamped compliant panel exposed to the intense shock-wave/boundary-layer interaction (SWBLI) induced by a compression ramp at Mach 10. Initial measurements of the underlying flowfield with a rigid ramp showed the incoming boundary layer to be transitional, and the SWBLI was observed to vary from attached to fully separated as the ramp angle was increased from 10 to 30 . For the compliant panel, a sealed cavity behind the panel allowed the effects of pressure-differential induced strains to be studied in the context of characterizing surface response to the aero-thermal load. Full-field, time-resolved panel deformations were measured using high-speed photogrammetry enabled by a new high-fidelity marker-tracking routine, which was shown to outperform existing methods. Substantial static panel deformations (of the order of several times the panel thickness) were produced by the intense aero-thermal loading environment. These deformations, combined with induced thermal and pressure gradients across the panel, were found to significantly modify the nature of existing panel modes (both the frequency and the displacement distributions) and introduce new, irregular mode shapes not predicted by classical clamped-plate theory; SolidWorks® simulations were performed to demonstrate that these new mode shapes were a result of the underlying panel curvature. Increasing the ramp angle resulted in a wider variety of panel modes becoming excited, while increasing the pressure differential across the panel typically produced further increases in modal frequencies and decreases in vibrational amplitudes. The transient panel response was characterized and it was found that the lower frequency mode shapes tended to gradually increase in vibrational frequency as the panel heated up and further deformed; however, higher frequency modes ( ) generally showed the opposite behavior. Furthermore, as the panel deformed through the test time, the average vibrational spectra root-mean-square power was generally found to monotonically decrease.

Tip-enhanced Raman scattering (TERS) enables real-space mapping of molecular vibrations and electronic excitations with subnanometer resolution, offering a direct route to track the molecular-size-dependent evolution of these properties. Here, using the hexagonal n-coronene series as a model system, we show that vibrationally resolved nonresonant TERS images of the ring-breathing mode can characterize a pronounced size-dependent redistribution where the spatial vibration migrates outward and becomes progressively concentrated at the molecular periphery as the molecule grows. This vibrational evolution is quantitatively captured by an envelope-based model. In contrast, resonant TERS imaging identifies two low-lying excited states with size-independent and distinct spatial characters across the series, including a delocalized lowest excitation and a persistently edge-localized second excitation. These findings serve as good references for future TERS experiments on visualizing size-driven property evolution, deepening our understanding of the crossover from molecule-like to graphene-like nanodisk behavior as π-conjugation expands.

The crystal structure, electron states and vibrational spectra of formamidinium bromide (FABr) crystals are studied with the use of quantum-mechanical density functional computational methods. The obtained results show good agreement when compared with available experimental data both in terms of structure and vibrational spectra. The spatial and electronic structure of FA cations in the crystal and molecular state are compared to identify the influence of the crystalline environment. It is shown that cation-anion binding is purely ionic. The bottom state of the conduction band corresponds to the LUMO state of the FA cation. The upper state of the valence band corresponds to the 4p lone-pair of the Br anion. Particular attention is paid to N-H⋯Br hydrogen bonds, for which the characteristic spectroscopic features are determined. Due to the low symmetry of the FABr crystal, the structure contains four nonequivalent N-H⋯Br hydrogen bonds. Analysis of the calculated and experimental results showed that the Raman and IR spectra in the 600-800 cm-1 region contain four clearly distinguishable peaks, each of which corresponds to the out-of-plane vibration of the FA cation localized on a separate hydrogen bond. This finding makes it possible to propose a spectroscopic method for monitoring the presence of various hydrogen bonds in the crystal under study and related compounds.

In contrast to a previous investigation of perfluoropropanoyl chloride, CF3CF2C(O)Cl, by microwave spectrometry which detected only the anti-conformer, the present structural investigation of CF3CF2C(O)Cl by gas electron diffraction (GED) allowed the detection of an additional gauche-conformer. Its double degeneracy by symmetry makes it more populated than the lower-energy anti-conformer. The conformational distribution as a function of temperature was studied by infrared spectroscopy. The enthalpy difference between the gauche- and anti-forms was determined by applying the Van't Hoff equation to resolved conformer bands in the vibrational spectrum. Additional gas phase conformational studies of perfluoropropanoyl bromide and iodide, CF3CF2C(O)Br and CF3CF2C(O)I, provide a comparison to the structures of CF3CF2C(O)F, CF3CF2C(O)OH and CF3CF2C(O)Cl, determined in this and previous work. The vibrational spectra of the title compounds are governed by the low anti-gauche rotational barriers. The magnitude and consequences of these barriers are determined by a detailed analysis of the spectroscopic data.

ABSTRACT Additively manufactured biomechanical models are increasingly being used in sports training simulations to evaluate athletes in terms of loading, risk of injury and performance optimisation. Their structural maintenance without destructive testing, however, is a major challenge and especially when their defects occur due to complicated interactions between materials and processes. The research introduces a fully non-invasive evaluation framework based on deep learning and capable of evaluating printed biomechanical structures with multimodal sensing and feature fusion. A multi-stage adaptive sensor fusion denoiser (MASFD) enhances deformation maps, displacement fields, strain contours, vibration spectra, bone-weighted dynamic fields and thermal gradients by removing modality-specific noise while preserving defect-sensitive features. The refined data are processed by a Hybrid Convolutional – Transformer Neural Network (HCTN-Net) integrating modality-specific CNN encoders, cross-modal attention fusion and dual-task prediction heads for defect classification and mechanical property regression. Experimental results demonstrate superior defect detection accuracy (96.8%), high F1-score (96.6%) and significantly reduced regression error (RMSE = 0.072, R 2 = 0.97) compared to baseline models. The proposed system enables reliable, contact-free, real-time structural assessment, supporting rapid design feedback and enhanced safety of sports training components.

The molecular water structure at charged aqueous interfaces is shaped by interfacial electric fields, which can induce significant anisotropy in the molecular orientations extending over nanometer-scale distances. Despite its great relevance, very little is known about the details of this depth-dependent anisotropic water structure, mainly due to the lack of appropriate experimental techniques. Here, we present a depth-resolved study of the water anisotropy at the interface with insoluble charged surfactants using a newly developed technique, which allows for directly correlating nonlinear vibrational spectra with depth information on the nanometer scale. We demonstrate that the obtained data allows for a reconstruction of the nonlinear vibrational responses as a function of depth. The results for the case of low-salinity solutions show the presence of two pronounced regions within the interfacial anisotropy with largely deviating degrees of preferential molecular orientations. A spectral analysis of the depth-dependent vibrational responses furthermore reveals that the natural local hydrogen-bond structure of bulk water remains largely unperturbed throughout the interfacial region, including water in direct proximity to the surface charges. These findings significantly refine our understanding of the anisotropic water structure at the interface with hydrophilic charged surfactants and showcase the large potential of our depth-resolved spectroscopic technique.

Quantum chemical calculations using ab initio methods and density functional theory have been carried out on the equilibrium structures and the vibrational spectra of the (valence) isoelectronic compounds N2L2 (L = N2, CO, CS, NO+, CN-). The molecules have a trans-periplanar arrangement of the L2 ligands at the N2 unit. The complexes with L = N2, CO, NO+, CN- are predicted as thermodynamically unstable for dissociation into N2 + 2L with ΔG 298 value lying in between -257 kcal mol-1 (L = NO+) and -73 kcal mol-1 (L = CO), but the adduct N2(CS)2 is calculated as slightly stable with ΔG 298 = 4 kcal mol-1. The homolytic dissociation reaction into two fragments N2L2 → 2 NL is energetically less favorable than the heterolytic fragmentation N2L2 → N2 + 2 L, which proceeds synchronously but asymmetrically. The activation barriers for the fragmentation reaction N2L2 → N2 + 2L have values between ΔG ≠(298 K) = 17 kcal mol-1 for L = N2 and ΔG ≠(298 K) = 84 kcal mol-1 for L = CS. The calculated vibrational frequencies suggest that the molecules N2L2 can be identified by the IR active antisymmetric stretching mode ν as of the ligands L, which is blue shifted for L = CO (Δ = 55 cm-1) and L = NO+ (Δ = 118 cm-1) but it is red shifted for L = CS (Δ = -242 cm-1) and L = CN- (Δ = -133 cm-1) relative to the ν as mode of L = N2. The analysis of the bonding situation reveals that there is a total charge donation L→(1Γ-N2)←L in all complexes, ranging between 1.38 e (L = CN-) and 0.56 e (L = N2), except in the dication with L = NO+, where a small backdonation in reverse direction L←(1Γ-N2)→L with 0.10 e is calculated. EDA-NOCV calculations of N6 show that the best description of the bonding situation is given in terms of dative interactions N2→(1Γ-N2)←N2 between central N2 in the excited (1)1Γg singlet state and the terminal N2 fragments in the 1Σg + electronic ground state. In contrast, the best description of the complexes with L = CO, CS, NO+ is calculated for the interactions between the central N2 in the 5Σu + quintet state and the terminal ligands in the symmetry-adapted (L)2 quintet state. For N2L2 with L = CN-, it is found that the bonding is best described for the interaction between N2 - in the electronic quartet (4Σu +) state and the terminal (L)2 - ligand as symmetry-adapted quartet. In contrast to the common bonding model for N6 using Lewis structures N-[double bond, length as m-dash]N+[double bond, length as m-dash]N-N[double bond, length as m-dash]N+=N-, the donor-acceptor model N2→(N2)←N2 explains that the lowest activation barrier is found for the concerted cleavage of the two formal double bonds, leading to the experimentally observed dissociation into 3 N2.

Surface-enhanced infrared absorption (SEIRA) spectroscopy has emerged as a powerful technique, amplifying inherently weak molecular vibration signatures to enable ultrasensitive detection of molecular structure and dynamics. However, conventional SEIRA platforms based on noble metals or 2D materials are fundamentally constrained by their narrow spectral bandwidths and limited access to high-frequency vibrational modes. Here, we demonstrate an ultrabroadband SEIRA approach that overcomes these limitations by activating acoustic plasmon modes in two-dimensional Ti3C2Tx MXene. These acoustic plasmons provide deep subwavelength confinement, compressing wavelengths by more than two orders of magnitude relative to free space in the short-wave infrared (SWIR), and sustaining an unprecedented spectral bandwidth of approximately 5000 cm- 1. Using this platform, we achieve simultaneous detection of distinct vibrational fingerprints-from high-frequency CH3 combination bands near 4700 cm-1 to low-frequency out-of-plane bending modes around 700 cm-1-in ultrathin analytes such as 8nm PMMA and 10nm graphene oxide films, with up to an order-of-magnitude sensitivity enhancement. These results establish acoustic plasmon modes in MXene as a transformative foundation for ultrabroadband, high-sensitivity deep-infrared spectroscopy, paving the way for next-generation molecular sensing technologies.

Non-equilibrium interactions between plasmonic metals and adsorbed molecules lie at the heart of emerging applications such as plasmonic photocatalysis and sensing, though the ultrafast charge and energy transfer mechanisms arising from these interactions are not well understood. Herein, we investigate the ultrafast dynamics of Au nano-islands tethered with a self-assembled monolayer (SAM) of electron-withdrawing 4-mercaptobenzoic acid (4MBA) molecules. Ultrafast UV-visible transient absorption spectroscopy following excitation of the interband transition in Au reveals three well-known, characteristic time constants that quantify electron-electron (el-el), electron-phonon (el-ph) and phonon-phonon (ph-ph) scattering lifetimes. When comparing the dynamics of bare Au and 4MBA-Au, we find that the el-ph and ph-ph scattering lifetimes are notably longer in 4MBA-Au. Density functional perturbation theory calculations ascribe the elongation in el-ph lifetimes in 4MBA-Au to the significant coupling of acoustic phonon modes of Au with certain molecular vibrations of 4MBA, leading to decreased spatial overlap between carrier electronic states and the acoustic modes. We speculate that the elongation of ph-ph scattering lifetimes in 4MBA-Au arises due to poor thermal conductivity of the SAM which disrupts efficient energy dissipation from Au to the environment, thus slowing down the thermalization of phonons. This work provides a glimpse into how molecular adsorbates modify the charge carrier and phonon dynamics of Au and sets the stage for further systematic exploration of plasmonic metal-molecule interactions.

The vibrational spectra of trans and cis-thioacrolein have been studied by 2nd order vibrational perturbation theory (VPT2) and vibrational configuration interaction (VCI) theory. All calculations rely on multilevel potential energy surfaces (PESs) with the highest level being explicitly correlated coupled-cluster theory including single and double excitation and a perturbational treatment of the triple excitation in combination with an augmented triple- basis set. Comparisons with experimental data are provided, including a number of predictions for unobserved fundamentals. Moreover, (ro) vibrational configuration interaction (RVCI) theory has been used for the simulation of the microwave spectrum, accompanied by the calculation of spectroscopic constants from perturbation theory.

The spectra of and its deuterated analogues are challenging to interpret due to the very flat potential surface and the highly delocalized ground state wave function. In this work, an approach is developed to model the spectra of and CH4D+. In this approach, several thousand geometries are sampled from the ground-state probability density, which is evaluated using diffusion Monte Carlo. For each structure, the potential energy is minimized with respect to the five CH bond lengths, and the frequencies and intensities for the five 1-0 transitions involving the CH or CD stretching vibrations are then evaluated using a five-dimensional harmonically coupled anharmonic oscillator model and a sum of one-dimensional cuts through the dipole moment surface. This information is used to obtain the spectrum by two approaches. To model the lower-resolution laser-induced reaction spectrum, the calculated spectrum is obtained by convoluting the spectra obtained at all of the sampled structures. To model the helium droplet spectrum, in which the individual CH vibrational transitions are resolved, the spectrum is obtained by averaging the Hamiltonian matrices and transition moment vectors over the sampled structures. We find that these approaches reproduce the reported spectra. Analysis of the helium droplet spectrum leads us to conclude that, in this environment, the isomerization of in its ground state is restricted compared to the gas phase. Overall, this approach provides a simple and physically transparent way to connect fluxional structures to CH-stretch spectral patterns, and offers frameworks for interpreting future spectroscopic studies.

The multi-mode anharmonic Brownian motion model provides a universal framework for simulating molecular vibrations in condensed phases. When vibrational energy surpasses thermal excitation, quantum effects become significant, necessitating a rigorous treatment of system-bath entanglement. The hierarchical equations of motion provide a powerful methodology for simulating such open quantum systems. In this context, two-dimensional vibrational spectroscopy (2DVS) constitutes a powerful probe for elucidating the complex dynamics of molecular processes, both experimentally and theoretically. This work introduces a computational implementation, HEOM-2DVS, for treating non-Markovian open quantum dynamics that encompass energy relaxation, dephasing, thermal excitation, and related processes arising from non-perturbative and nonlinear interactions between selected vibrational modes and their thermal environments. To validate the theoretical framework, we computed 2D correlation infrared spectra for three coupled intramolecular vibrational modes of water. The HEOM-2DVS program, developed for both the CPU and graphics processing unit, is provided as the supplementary material.

Simulations of vibrational spectra are important for interpreting experimental data as well as understanding molecular structure and dynamics. Herein, we present an approach for the efficient and accurate incorporation of anharmonicity into such simulations. Real-time nuclear-electronic orbital time-dependent density functional theory treats specified protons quantum mechanically on the same level as the electrons, propagating the electronic and protonic densities according to the time-dependent Schrödinger equation. This approach inherently includes the anharmonicity of the quantum protons and can be combined with Ehrenfest dynamics for the classical nuclei. Herein, this real-time nuclear-electronic orbital (NEO)-Ehrenfest approach is combined with the quasiclassical trajectory (QCT) approach for generating initial conditions that include the zero-point energy of the classical nuclei, thereby enabling sampling of the anharmonic regions of the potential energy surface. The resulting NEO-QCT approach is shown to capture the anharmonic heavy nuclear motion, as well as the anharmonicity of the quantum protons, for a series of molecular systems, including HCN, HNC, FHF-, CH2O, and HCOOH. The NEO-QCT method also captures the distinct spectral features of the formate-water complex (CHO2-⋅ H2O), including the redshifted and broadened OH stretch band due to strong anharmonicity arising from hydrogen bonding and coupling between the motions of the hydrogen nuclei and the heavy nuclei. The NEO-QCT method enables computationally practical simulations of vibrational spectra of molecules that exhibit significant anharmonicity and coupling between vibrational modes.

Accurate quantification of phosphogypsum (PG) filler in epoxy composites is essential for quality control and performance optimization. Conventional separation by muffle furnace calcination suffers from slow epoxy decomposition and risks thermal degradation of CaSO4, leading to inaccurate PG quantification. This study introduces a microwave-assisted separation method that leverages molecular vibration heating to achieve faster heating rates and more uniform temperature distribution, enabling complete epoxy removal while minimizing CaSO4 decomposition. Comprehensive characterization (X-ray diffraction, XRD; Fourier transform infrared spectroscopy, FT-IR; scanning electron microscopy-energy dispersive spectroscopy, SEM-EDS) confirms the structural integrity of the isolated PG filler. Among five quantification methods evaluated, inductively coupled plasma optical emission spectrometry (ICP-OES) based on sulfur content provides the highest accuracy (spike recovery: 91–99.8%, relative standard deviation, RSD ≤ 4.2%), while gravimetry suffices for single-filler systems. This work establishes a reliable analytical framework for PG characterization in epoxy composites, supporting quality control and resource valorization.