Study of the biomolecular composition of skeletal muscle fibres affected by different types of pathology using by FTIR microspectroscopy.

Oxidative stability and molecular degradation of aviation fuels characterized by Raman spectroscopy.

Dual-mode mid-infrared plasmonic metasurface for real-time label-free analysis of live cells.

Ultraviolet and infrared photodissociation spectra (UVPD and IRPD) of monohydrated N-methyl-dopamineH+ NMeDAH+(H2O)1 are measured by cryogenic ion spectroscopy and compared with those of monohydrated dopamineH+ DAH+(H2O)1 to reveal the methylation effect on intramolecular excited state proton transfer (ESPT). Whereas the UVPD spectrum of DAH+(H2O)1 is broad due to the proton transfer from the amine chain to the aromatic ring, that of NMeDAH+(H2O)1 shows sharp vibronic transitions in addition to a broad background signal. This suggests the coexistence of two or more conformers in which the excited state dynamics are very different. Based on conformer-selected IR spectra and theoretical calculations, sharp bands are assigned to two conformers in which a water molecule is inserted between the amine chain and the aromatic ring and prevents NH → π ESPT. This will lead to slow excited state dynamics. This water-inserted conformer is very minor in DAH+(H2O)1, and its enhancement by methylation is discussed. The broad UVPD background is attributed to the most stable conformer, in which the N-H bond of the amino group directly interacts with the catechol ring. The reaction path for NH → π ESPT in the most stable conformer shows a low barrier of less than 100 meV, which explains the broad UVPD spectrum by fast ESPT. The results confirm the model based on the relationship between the structure of these hydrated complexes and their photo reactivity associated with the excited state proton transfer.

Understanding amyloid fibril formation through interfacial peptide self-assembly remains a fundamental challenge in both neurodegenerative disease pathology, particularly Huntington's disease and related polyglutamine disorders characterized by pathogenic amyloid aggregation. Current therapeutic approaches to regulate amyloid aggregation face challenges in precision, invasiveness, and unintended biological effects. In this study, we introduce a noninvasive method leveraging vibrational strong coupling (VSC) within optical microcavities to selectively inhibit polyglutamine (polyQ) peptide fibrillation. By resonantly coupling the O-H vibrational mode of water molecules (1645 cm-1) to the confined electromagnetic field, fibril formation was significantly suppressed by 42.5%. The inhibition efficacy shows a good alignment with the strength of VSC with O-H bending vibrational band. Morphological analysis revealed a 3-fold reduction in fibril density and shortened fibril lengths (153 nm vs 452 nm in controls), with obvious disruption in β-sheet network formation compared to uncoupled controls. Molecular dynamics simulations reveal that cavity-induced rearrangement of interfacial water restricts peptide nucleation. These results establish solvent-vibration control as a distinctive route to modulate amyloid aggregation, positioning VSC as a precise and noninvasive tool for studying molecular self-assembly and protein misfolding.

Vibration band gap structures are advanced materials for vibration wave mitigation from metamaterials to phononic crystals from simple geometrical manipulations. Here, we present geometrical structures, made from platonic solids, that are capable of providing multi-passband frequency ranges with face symmetry in each unit cell. We fabricated the metamaterial structures using stereolithography, after which we experimentally characterized band gaps through impulse vibration testing. Experimental results have shown that the band gaps can be changed for different types of platonic structures along with the loading direction. This provided a comparison between axial and two bending direction band gaps, revealing ranges where the structures behave in either a “fluid-like” or an “optical-like” manner. Dodecahedron unit cells have exhibited the most promising results, when compared with reduced relative densities and a number of stacking unit cells. We utilized the coherence function during signal processing analysis, which provided strong predictions for the band gap frequency ranges.

We investigate the origin dependence in the computation of vibrationally resolved electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) spectral shapes with particular attention to non-Condon approximations. To that end, we adopt the length and velocity representations for the electric transition dipole moment (TDM), expressing both electric and magnetic TDMs as Taylor expansions in nuclear coordinates, including the constant (Franck-Condon, FC), non-Condon linear (Herzberg-Teller, HT) and, in some cases, second-order terms. Our analysis evidence that HT spectra, in the standard formulation, i.e., including the full first-order expansions of both TDMs, are not origin invariant, even in the velocity gauge. This inconsistency arises because the corresponding expression for the rotatory strength, which, unlike the individual TDMs, directly encodes the measurable chiroptical response, involves an incomplete second-order expansion. We show that origin invariance in the velocity gauge is restored when the product terms between the electric and magnetic TDM expansions are selected to yield a complete either first- or second-order expansion of the rotatory strength. In particular, excluding the cross-linear terms in the HT expression results in a consistent linear expansion, which delivers origin invariant rotatory strengths and ECD/CPL lineshapes. We refer to this formulation as the approach. Similarly, including the additional terms required for a complete second-order expansion, i.e., those combining constant and quadratic TDM terms, defines the approach, which also produces origin-invariant rotatory strengths. However, the ECD/CPL spectra lineshapes computed at this level still depend weakly on the gauge origin because the intensity of each single vibronic transition does. Nonetheless, the fact that the integrated ECD/CPL lineshapes remain origin invariant effectively mitigates origin-related variations in the spectra. Simulations of ECD and CPL lineshapes for three representative systems, spanning different non-Condon strengths and sensitivities to the gauge origin, confirm these predictions. All calculations are performed at the TDDFT level, using analytical first-order derivatives and numerical second-order derivatives of the TDMs with respect to nuclear coordinates. The analytical time-correlation functions necessary to run and vibronic computations, in a time-dependent framework, were derived in harmonic approximation, providing a general and robust route toward origin-independent vibronic simulations of chiroptical spectra.

Elucidating the mechanistic pathways of methane (CH4) electrooxidation is crucial for advancing sustainable C1 chemical synthesis. Herein, we report a comprehensive mechanistic picture of CH4 activation and conversion on Pt/C membrane electrode assemblies (MEAs), through highly sensitive operando infrared spectroscopy and density functional theory (DFT) calculations. A characteristic vibrational band at ∼2916 cm-1, assigned to a key intermediate of *CH species formed via CH4 dehydrogenation, was detected across a wide potential window from -0.4 to 0.3 V vs RHE. This activation step is thermodynamically favorable and nearly potential independent. In contrast, the subsequent oxidation of *CH to *CO, *COOH, and ultimately, CO2 is strongly governed by applied potentials and competitive *OH adsorption. DFT calculations validate the energetics and site-specific interactions of these intermediates, highlighting the critical role of surface coverage and adsorbate migration in controlling reaction selectivity. These findings provide direct spectroscopic evidence for CH4 activation on Pt surfaces and suggest that stabilizing and selectively oxidizing *CH intermediates represent key challenges for catalyst design. This study establishes a mechanistic foundation for the rational design of catalysts capable of selective CH4 electrooxidation.

Controlling electron dynamics at optical clock rates is a fundamental challenge in lightwave-driven nanoelectronics and quantum technology. Here, we demonstrate ultrafast charge-state manipulation of individual selenium vacancies in monolayer and bilayer tungsten diselenide using picosecond terahertz source pulses, focused onto the junction of a scanning tunneling microscope. Using pump–probe time-domain sampling of the defect charge population, we capture atomic-scale snapshots of the transient Coulomb blockade, a hallmark of charge transport via quantized defect states. We leverage the Franck–Condon blockade, which restricts accessible vibronic transitions and promotes unidirectional charge transport, to effectively mitigate back tunneling to the tip electrode. Our master equation approach models the non-reciprocal tunneling process due to vibrations and angular momentum multiplicities, accurately reproducing the time-dependent tunneling current across different coupling regimes. Capturing and controlling ultrafast charge dynamics in low-dimensional materials at the atomic scale opens frontiers in lightwave-driven nanoscale science and technology.

Mid-Infrared line intensity for the fundamental (1–0) vibrational band of carbon monoxide (CO)

This work designed and optimized geopolymer injection mixtures suitable for curing under ambient conditions using fly ash (FA) and ground granulated blast furnace slag (GGBFS) as industrial waste-based binders. Water/binder (w/b) ratios were systematically tested in the range of 0.50–1.50, and 12 M sodium hydroxide (NaOH) together with sodium silicate (Na₂SiO₃) were used as activators, with the activator/binder and Na₂SiO₃/NaOH ratios fixed at 0.4 and 2.5, respectively. Sustainable industrial by-products have been combined with a systematic mix design to provide environmental benefits under mechanical efficiency and practical curing conditions. The effects of GGBFS content and w/b ratio on setting time, flow time, and compressive strength have been evaluated to determine optimal mixes for practical injection applications. To achieve early-age strength without requiring high-temperature curing, GGBFS was selected. Analysis of Variance (ANOVA) was applied to validate the parameters. The Marsh flow cone test was conducted to evaluate the injectability of the mixtures, and flow times were recorded. Compressive strength tests demonstrated that mechanical performance was greatly enhanced by increasing the GGBFS content, especially at low w/b ratios. With a strength of roughly 67 MPa, the GP-0.5 mixture (w/b = 0.50, 50% GGBFS) produced the best results regarding binder interaction and dense matrix formation. On the other hand, greater porosity was found to cause a loss in strength at high w/b ratios (> 1.0). Microstructural experiments (FE-SEM and EDX) revealed that compact gel phases occurred, and Ca-Si-Al-rich phases improved structural strength. The formation of aluminosilicate networks and the chemical evolution of the binder matrix were supported by the distinct vibration bands observed in FTIR and the crystal/phase analyses determined by XRD.

A novel copolymer based on sulfonated N-alkylated styrene-vinyltetrazole was synthesized. Copolymers were prepared by a 1,3-dipolar Huisgen cycloaddition reaction from their corresponding previously synthesized styrene-co-acrylonitrile copolymers and subsequently alkylated with aliphatic chains of 4, 6 and 8 carbon atoms. Finally, they were sulfonated using H2SO4 as sulfonating agent for 4 hours. The chemical structure of the copolymers was analyzed by FT-IR and 1H and 13C NMR, the thermal properties were evaluated by DSC and TGA. Membranes of the sulfonated copolymers were prepared using the casting method and their IEC evaluated by titration, water uptake (WU) by gravimetry and its electrochemical properties by EIS. Sulfonated membranes were also characterized mechanically by TMA. The sulfonated, non-sulfonated and alkylated copolymers exhibited the vibrational bands and chemical shifts with the signals corresponding to the functional groups associated with the involved comonomers, as well as the sulfonic group. Sulfonated copolymers exhibited an increase in Tg values compared to the non-sulfonated ones in addition to a good thermal stability for the desired application. Sulfonated and alkylated copolymers reduced their complex moduli (E*), but their values depended on the number of carbons in the aliphatic chain. Sulfonated copolymers exhibited high IEC values and a sulfonation degree of 38% was calculated. Proton conductivity for St/VTz-91:8C:S membrane (6.86x10-3 S.cm-1) was close to that obtained for the Nafion 117 membrane (7.6x10-3 S.cm-1). These copolymers are interesting for further investigation for their use as polymeric electrolytes for fuel cells.

In this study, a new organometallic benzoxazine monomer (BA-Al) was synthesized by incorporating an aluminum (Al) atom into the structure of bisphenol A (BPA) to obtain the Al-BPA molecule. The BA-Al monomer was then synthesized through a one-step Mannich reaction. The molecular structure of Al-BPA was confirmed by proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopy (FTIR), revealing new peaks in the 1 H NMR spectrum due to the formation of Al-O bonds. The FTIR spectra also showed the characteristic Al-O vibration bands. For the BA-Al monomer FTIR analysis confirmed the presence of benzoxazine rings with characteristic bands. Additionally, peaks were associated with Al-O bonds. 1 H NMR analysis further confirmed the BA-Al structure, providing evidence for the presence of the oxazine ring. DSC analysis showed that BA-Al cures at a lower temperature compared to BA-a, likely due to the influence of aluminum. The TGA analysis of P(BA-Al) indicated significant degradation, while P(BA-a) starts decomposing at a higher temperature. Dynamic mechanical analysis (DMA) analysis revealed that P(BA-Al) has a lower storage modulus and glass transition temperature compared to P(BA-a). Monotonic tensile tests showed that both P(BA-a) and P(BA-Al) exhibit similar tensile strength and elongation trends at varying strain rates, but P(BA-a) consistently shows slightly higher ductility. Solubility tests indicated that both BA-a and BA-Al monomers exhibit good solubility in polar aprotic solvents, while the corresponding polymers show reduced solubility, with P(BA-Al) being more soluble in DMF and DMSO. Electrical conductivity measurements showed that Al-BPA has a conductivity of 89.92 S/m, BA-Al has a conductivity of 67.98 S/m, while BA-a exhibited negligible conductivity. This suggests that aluminum content plays a crucial role in enhancing electrical conductivity. The synthesized BA-Al monomer demonstrates promising properties for specialized applications, particularly in the field of electromagnetic protection.

A polycrystalline sample of Sr(Mn 1/2 Nb 1/2 )O 3 (SMNO) was synthesised via the solid-state reaction method, confirming a single-phase perovskite structure. Room-temperature XRD analysis revealed a tetragonal crystal system. Micro-Raman spectroscopy exhibited broad peaks, suggesting the presence of a vibrational band and ferroelectric characteristics. Dielectric properties were investigated over a broad frequency (100–1 MHz) and temperature (24–360°C) range, revealing strong low-frequency dispersion, a very high dielectric constant and loss (∼6). A broad permittivity peak was observed at 280°C across all measured frequencies. The frequency and temperature dependence of the ac conductivity (σ ac ) suggest a thermally activated relaxation mechanism. Impedance spectroscopy indicated that the dielectric and conductive properties of the material arise from the contributions of bulk, grain boundaries and electrode effects. Magnetic measurements identified an antiferromagnetic transition at 41 K, co-existing with a low-temperature ferromagnetic phase. The growing demand for miniaturised and versatile electronic components drives our strong interest in developing dielectric ceramics. These materials are critical for applications such as capacitors, sensors, actuators and transducers.

Centroid molecular dynamics (CMD) incorporates nuclear quantum statistics into the calculation of vibrational spectra. However, when CMD is performed in Cartesian coordinates, it shows unphysical artifacts in certain vibrational bands, known as the curvature problem. Recent work showed that CMD spectra can be freed from the curvature problem by evolving the ring-polymer centroid on a potential of mean force (PMF) calculated at an elevated temperature (Te-CMD). Here, we present a partially adiabatic implementation of Te-CMD (PA-Te-CMD), which eliminates the need for precomputed PMFs and instead yields the centroid force on the fly. We introduce a two-temperature path-integral Langevin thermostat to achieve a temperature separation between the centroid and internal modes of the ring polymer. Because it is paramount that the elevated temperature be chosen as low as possible for a given physical temperature in this formulation, we present a general scheme for its determination. We benchmark PA-Te-CMD against exact vibrational spectra for the isolated water monomer and discuss its performance for challenging anharmonic systems: the carbonic acid fluoride molecule and the methylammonium lead iodide perovskite. We conclude that PA-Te-CMD mitigates the curvature problem and the steep increase in computational cost with decreasing temperature of conventional path-integral methods. We observe energy leakage from the hot internal modes to high-frequency centroid modes in some cases, which, nevertheless, only compromises the spectral line shapes at lower temperatures. While an adiabatic setup based on a coarse-grained centroid PMF is still preferable when a good pre-trained PMF can be easily obtained, PA-Te-CMD presents a low-barrier single-shot setup for any system.

Molecular polaritons within the mid-infrared regime have emerged as a source for modifying and manipulating molecular and photonic properties. However, the development of new methodologies for photon generation is still a challenge in nanophotonics. We propose a molecular model based on the Holstein-quantum-Rabi Hamiltonian, which also incorporates realistic dipole moments and nonadiabatic couplings among electronic excited states, to study the ultrafast photodynamics of diatomic molecules in confined electromagnetic fields within quantized cavities. In addition to vibronic transitions due to intrinsic nonadiabatic couplings, two types of light-induced crossings emerge: one type is located at molecular nuclear geometries where the rotating wave approximation is fulfilled, and another type appears at different geometries where counter-rotating transitions may occur. We make a comprehensive study of polariton photodynamics within a time window of a few tens of femtoseconds, where dissipative mechanisms do not influence the polariton photodynamics. We stress the dramatic change of the polariton energy spectrum as a function of the Huang-Rhys factor when nonadiabatic couplings are included in the model. We conclude that both the molecular nonadiabatic couplings and, more specifically, the counter-rotating couplings in the cavity-molecule interaction play a crucial role in converting vibronic energy into photons through excited dressed states. We also show that the signof the Huang-Rhys factor has a significant impact on this photon conversion. Our work paves the way for the development of many-photon generation powered by strong light-matter interaction, along with potential applications using alkaline earth monohydride molecules.

The orientational and conformational changes of individual protein molecules are particularly attractive. However, current methodologies struggle to directly observe these transient states of single-molecule (SM) proteins. In this study, we developed a real-time dynamic SM surface-enhanced Raman scattering (SM-SERS) tracking system based on gold plasmonic nanopores with small orifices. This system enables continuous monitoring of protein orientation changes with subsecond temporal resolution. SM lysozymes (Lyz) were driven by ionic currents and trapped in the gold plasmonic nanopores, exhibiting typical residence times of a few seconds. The SM-SERS spectra were obtained with a 300 ms temporal resolution; Raman vibrational bands representing different chemical groups appear at different times, which represent the dynamic orientational changes of SM Lyz. Different plasmonic nanopores provided similar time-averaged SM-SERS spectra for SM Lyz, suggesting that the present system can reveal regular orientation states of SM proteins. Additionally, we observed a significant difference between the time-averaged SM-SERS spectrum and the multimolecule SERS spectrum, emphasizing the importance of attributing characteristic peaks to discover protein orientation. This study demonstrates great potential for elucidating the orientation of SM proteins and represents a promising advancement toward SM protein sequencing.

Abstract Our knowledge of the chemical composition of the gas in the inner disc of intermediate-mass young stars is limited, due to the lack of suitable instrumentation. The launch of JWST has provided a significant improvement in our ability to probe gas in these inner discs. We analyse the gas composition and emitting conditions of the disc around HD 35929, a young intermediate-mass Herbig star, using MIRI/MRS data. Our goal is to constrain the chemistry and kinematics of the gas phase molecules detected in the inner disc. We use iSLAT to examine the observed molecular lines and DuCKLiNG to detect, fit, and analyse the molecular emission. We find gas phase H2O, CO, CO2, and OH in the disc, as well as HI recombination lines. Surprisingly, we also detect gas phase SiO in the fundamental v=1-0 vibrational band. We derive column densities and temperature ranges of the detected species, arising from the inner $\sim 0.2\, \rm au$, hinting towards a compact and very warm disc. The molecular column densities are much higher than found in lower mass T Tauri discs. In general, the molecular composition is consistent with an O-rich gas from which silicate-rich solids condense and the strong gas phase molecular line emission suggests a low dust opacity. The unexpected detection of gas phase SiO at the source velocity points to an incomplete condensation of rock forming elements in the disc, suggesting chemical disequilibrium and/or an underestimate of the gas kinetic temperature.

Dimethyl zinc Zn(CH3)2 in He was photolyzed at 223nm in a flow cell at 298K, and the photoproduct ZnCH3 was detected with laser-induced fluorescence via the Ã2E-X̃2A1 transition. The excitation spectrum showed the sharp peaks of the K structure of the 610 (v' = 0 ← v6 = 1) vibrational band in the Ã2E1/2-X̃2A1 and Ã2E3/2-X̃2A1 transitions. A spectroscopic simulation well-reproduced not only the transition energies of the K subbands but also the intensity alternation of the peaks due to the nuclear spin statistics of the three hydrogen atoms of the methyl group. The vibrational frequency of the ν6 mode of the X̃2A1 state has been determined to be 587cm-1, which replaces the previously reported value of 315cm-1. The transition energies of the band origins are 23 362 and 23 617 cm-1 for the 610 bands whose upper states are Ã2E1/2 and Ã2E3/2, respectively. Based on the relevant literature studies, we have shown that the 0-1 band of the degenerate vibration of a symmetric top is allowed in the transition between electronic states at least one of which is degenerate.

Fullerenes are among the most abundant carbon-bearing molecules in the interstellar medium. Their ionic forms, as well as clustered structures, might exhibit strong absorption features in the infrared spectral region. Experimental spectra of cold molecules in the gas phase are crucial for matching astrophysical observations with the corresponding compounds. In this work, employing He-tagging spectroscopy, we present the first gas-phase spectra of the cationic and anionic C70 dimers, (C70)2±, in the spectral range between 4.5 and 12μm. Quantum chemical calculations are employed to interpret the experimental spectra in terms of plausible dimer structures, indicating the coexistence of multiple isomers that contribute to the observed vibrational features. In contrast to the weakly absorbing C70± monomers, the strong absorptions, especially toward lower wavelengths below 6μm, indicate that (C70)2± would be, in principle, detectable in astrophysical observations. While monomeric fullerenes such as C60+ and C70+ have been identified in several photodissociation regions, our data suggest that the formation of dimers is unlikely under astrophysical conditions, as their characteristic bands are absent in observational IR spectra. The experimental vibrational bands do not align with the strongest features of the unidentified infrared bands in the 6.5-9μm range, where current assignments for PAHs and fullerenes remain debated.