Raman Spectroscopic Study Research Articles

Raman spectroscopy study of the influence of additives (Cr-, Cr/Al-, and Gd) on UO2 dissolution behavior

Abstract In this work, Raman spectroscopy (RS) has been used to study the behavior of spent nuclear fuel (SNF) under disposal conditions. In particular, evolutionary Accident-Tolerant Fuels (ATFs) consisting in UO2 doped with Cr and Cr/Al; as well as neutron absorbers (UO2 doped with Gd), has been manufactured and studied. The prepared pellets have been exposed to three different pH leachants (inert media, carbonated media, and young cement water with calcium) for distinct times. RS analyses have been conducted in both the leached and the unleached pellets. The results show that the addition of Cr, and Cr/Al does not lead to a noteworthy change of the pellet surface under the three media considered. Gd doping induces a higher intensity of the so-called “defects band,” which is not dramatically affected after leaching. No secondary phases have been observed. These results are in good agreement with previous studies by XRD and SEM, thus validating RS as an accurate analytical technique. Graphical abstract

Enhanced oxygen ion conductivity in Ba3W1+xV1−xO8.5+x/2 (− 0.2 ≤ × ≤ 0.2) hexagonal perovskite derivative compounds

Abstract A series of hexagonal perovskite derivative compounds Ba3W1+x V1−x O8.5+x/2 (x = − 0.2, − 0.1, 0, 0.1, 0.2) with varying oxygen content was synthesized by high-temperature solid-state reaction route and characterized using X-ray diffraction, SEM–EDX, Raman spectroscopy, XPS, and dielectric spectroscopy. All samples were isostructural, having features of both palmierite and 9R hexagonal perovskite. The unit cell volume showed a continuously decreasing trend with increasing oxygen content. The XPS studies showed no deviation of oxidation states of W6+ and V5+ and hence confirmed that the oxygen stoichiometry is solely controlled by the W to V ratio in the samples. The presence of both octahedral MO6 and tetrahedral MO4 units in all samples was inferred from temperature-dependent Raman spectroscopic studies. The translational and rotational motion of MO4 tetrahedra are appreciably affected by temperature. The dc conductivity was obtained directly from the complex ac conductivity derived from temperature-dependent dielectric measurements. It was found that the dc conductivity increases when the composition deviates from x = 0.0, i.e., W:V = 1:1. An estimate of the ion mobility and mobile ion concentration was obtained using the Almond-West formalism. The conductivity was found to be significantly higher in W-rich compounds (x > 0), and the ion mobility was also correspondingly higher. It could be inferred that the compositional dependence of unit cell parameters, particularly a- or b-axis, and the oxygen stoichiometry, play crucial roles in governing the ionic conductivity of these hexagonal perovskite derivatives.

Microstructural, optical, and impedance studies of porous Mn-α-Fe2O3/CuO/Ag heterostructures grown using solution-based methods

Here, thin films of porous Mn-α-Fe2O3/CuO/Ag were prepared; engaging solely low-cost solution-based methods. The dip-coating of CuO on electrodeposited Mn-α-Fe2O3 samples using a 180-day-old Cu-based precursor produced films with inhomogeneous morphology and shallow surface pores. This morphology provided the platform for the drop-casting of Ag nanoparticles on the film’s surface to form porous Mn-α-Fe2O3/CuO/Ag heterostructures. EDS, XRD, and Raman spectroscopy studies affirmed the film’s structural integrity. The bandgap estimated for the Mn-α-Fe2O3/CuO/Ag samples was 3.8 % less than the values deduced for Mn-α-Fe2O3 films. Mott-Schottky analysis disclosed n-type semiconducting behaviour for the Mn-α-Fe2O3 films, which was retained after forming heterostructures with CuO and CuO/Ag. The charge transfer resistance at Mn-α-Fe2O3/CuO/Ag film’s surface in an electrochemical system was 27 times lower than the approximate values obtained for Mn-α-Fe2O3 samples. This research introduces a facile and low-cost approach for fabricating porous Mn-α-Fe2O3/CuO/Ag heterostructures with improved properties for photo-base and optoelectronic applications.

Plasmonic Slippery Surface for Surface-Enhanced Raman Spectroscopy and Protein Adsorption Inhibition.

Slippery liquid-infused porous surfaces (SLIPSs) are a class of surface that offers low contact angle hysteresis and low tilt angle for water droplet shedding. This property also endows the surface with pinning-free evaporation, which in turn has been exploited for analyte concentration enrichment for Surface Enhanced Raman Spectroscopic applications and antibiofouling. Herein, we demonstrate a facile approach for creating SLIPS with low contact angle hysteresis and low tilt angle for water shedding by coating the equal-volume mixture of polydimethylsiloxane (PDMS) and silicone oil. By exploiting the in situ plasmonic particle reduction capability of the PDMS, the surface is converted to plasmonic SLIPS, which illustrates its potential as a sensitive analytical platform via surface-enhanced Raman spectroscopy. The Raman spectroscopic studies using crystal violet as a reference sample show a limit of detection of 76 pM. Further, we have demonstrated that the fabricated plasmonic substrate is found to be more efficient in inhibiting proteins (bovine serum albumin) on the surface compared to pristine PDMS surfaces. Our fabricated plasmonic surface can find applications in ultrasensitive molecular detection for applications related to analytical chemistry, diagnostics, environmental monitoring, and national security and more importantly can control the nonspecific adsorption of proteins.

Impact of the Applied Electrode System on Properties of Electrodeposited Calcium Phosphate Coatings

The morphology and physicochemical properties of electrochemically deposited CaP coatings depend on the applied process parameters; however, the influence of different electrode systems has not been studied so far. In this work, the possibility of electrochemical deposition of CaP coatings on Ti6Al7Nb alloy using different electrode systems (two-electrode and three-electrode) and the influence of the electrode system and selected ranges of deposition parameters on the properties of the deposited CaP coatings were investigated. The morphology and physicochemical properties of the CaP coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), and corrosion studies. The results confirmed the effective electrodeposition of CaP coatings using both electrode systems. The applied electrode system and deposition parameters cause changes in the morphology of the obtained coatings. Chemical structure analysis confirmed the presence of mainly hydroxyapatite in the deposited CaP coatings. With the change in voltage/potential in a more cathodic direction, in addition to hydroxyapatite, a dicalcium phosphate dihydrate (DCPD) structure appears. The corrosion tests have shown that the applied deposition parameters have an impact on corrosion resistance and the deposited coatings exhibited protective properties against corrosion under physiological conditions. The CaP coatings with optimal properties for biomedical applications were deposited at a voltage of −4 V in the two-electrode system and a potential of −4 VSCE in the three-electrode system.

Effects of supplementation of macular pigment carotenoids on ocular health: a Raman spectroscopic study of human blood serum of glaucoma patients.

Carotenoids are known for their antioxidant and vision protection roles, with dietary supplements often promoted for eye health. An initial trial, the European Nutrition in Glaucoma Management (ENIGMA), assessed macular pigment optical density (MPOD) and other ocular parameters before and after supplementing glaucoma patients with macular pigment (MP) carotenoids. The trial confirmed significant improvements in clinical ocular health. Blood, containing all major dietary carotenoids, serves as an efficient medium for in vivo analysis of carotenoids. Raman spectroscopy, an effective analytical tool, was used to measure the impact of supplementation on serum carotenoid levels and their correlation with MPOD and other ocular responses. Serum samples from baseline and 18-month supplemented participants were analysed. An inverse relationship was found between the percentage change in Raman intensity over the supplementation period and baseline Raman serum measurements, indicating greater relative benefits for people with low MPOD/serum carotenoids pre-supplementation. Partial least squares regression (PLSR) was employed to analyse the spectra after pre-processing, and the loadings reflected the carotenoid content and structural profile. MPOD results correlated at all eccentricities, with a coefficient of determination (R2) of 0.62-0.92 and %Root mean squared error of <44%. Structural, functional, and perceptual parameters also showed good correlation with serum Raman measurements. The results support the ENIGMA trial conclusions, and suggest strategies for optimizing patient responses to supplementation based on baseline carotenoid levels. Additionally, Raman spectroscopy of serum carotenoids shows significant potential as a simple and reliable method for investigating macular pigment carotenoids and assessing patient health.

Defect-mediated electron–phonon coupling in halide double perovskite

Optically active defects often play a crucial role in governing the light emission as well as the electronic properties of materials. Moreover, defect-mediated states in the midgap region can trap electrons, thus opening a path for the recombination of electrons and holes in lower energy states that may require phonons in the process. Considering this, we have probed electron–phonon interaction in halide perovskite systems with the introduction of defects and investigated the thermal effect on this interaction. Here, we report Raman spectroscopic study of the thermal evolution of electron–phonon coupling, which is tunable with the crystal growth conditions, in the halide perovskite systems Cs2AgInCl6 and Cs2NaInCl6. The signature of electron–phonon coupling is observed as a Fano anomaly in the lowest frequency phonon mode (51 cm−1), which evolves with temperature. In addition, we observe a broad band in the photoluminescence (PL) measurements for the defect-mediated systems, which is otherwise absent in defect-free halide perovskite. The simultaneous observation of the Fano anomaly in the Raman spectrum and the emergence of the PL band suggests the defect-mediated midgap states and the consequent existence of electron–phonon coupling in the double perovskite.

Identification of high-risk oral leukoplakia (OLK) using combined Raman spectroscopic analysis of brush biopsy and saliva samples: A proof of concept study.

The gold standard method of diagnosis of oral leukoplakia (OLK) is a tissue biopsy followed by histological examination. Raman spectroscopic studies of cytological brush biopsy and saliva samples have previously been shown to differentiate low (no and mild dysplasia) and high risk (moderate and severe dysplasia) OLKs, discriminant models of cellular samples achieving higher specificity, whereas those based on saliva samples achieved higher sensitivity. The current study combines the spectral data sets of cell and saliva samples in an attempt to improve the overall efficiency of the discriminating models. Raman spectral data from cellular (nucleus and cytoplasm) and saliva samples, collected from patients with OLK (n=12), was analysed as a concatenated or fused dataset and as data blocks in a multiblock analysis. The concatenated data was subjected to partial least squares-discriminant analysis (PLS-DA) to discriminate high and low grade dysplasia. Finally, multi-block analysis was performed using sequential orthogonalised PLS-DA, by which each set of data blocks was combined sequentially to provide maximum discrimination. For the concatenated dataset of cells and saliva, 87% sensitivity and 76% specificity were achieved, while in the case of the multi-block analysis, 97% sensitivity and 100% specificity were achieved. It is concluded that multiblock analysis provides maximum sensitivity and specificity using both cell and saliva datasets, compared to fused datasets. This study demonstrates that Raman spectroscopy of minimally invasive brush biopsy and saliva samples could have a role in differentiating high and low-risk OLKs.

Raman spectroscopy study of K-birnessite single crystals

The alterations in the crystal structure and Raman spectra of K-birnessite single crystals when water molecules intercalate into or deintercalate from the interlayer space were subjected to an in-depth examination.

Correction: Raman spectroscopy study of K-birnessite single crystals

Correction for ‘Raman spectroscopy study of K-birnessite single crystals’ by Dong Han Ha et al., J. Mater. Chem. A, 2025, 13, 617–626, https://doi.org/10.1039/D4TA06118G.

Effect of Copper Substitution on Structural, Electrical, and Magnetic Properties of Nanocrystalline Cobalt Ferrites for Memory Storage Applications

Cu2+‐ion‐doped cobalt ferrites with the chemical formula Co1–xCuxFe2O4 (0 &lt; x ≤ 0.20) are prepared using the citrate–nitrate autocombustion method. The structural properties of the synthesized samples are examined by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The XRD studies reveal the formation of a single‐phase spinel cubic structure. A slight variation in the peak position is observed with the addition of Cu2+ ions. The proposed cation distribution is supported by X‐ray relative intensity calculations. FTIR and Raman spectroscopy studies also confirm the formation of a single‐phase cubic structure. Field‐emission scanning electron microscopy (FESEM) is used to measure the surface properties of the samples. The FESEM images reveal nearly uniform‐sized grains with the addition of Cu2+ ions. The DC electrical resistivity is determined using the conventional two‐probe technique and is typically found within the range of 106 Ω cm−1. Dielectric measurements are performed using an impedance analyzer with 100 Hz–10 MHz frequency range and the variations in the dielectric properties are discussed. The magnetic properties are measured using a vibrating sample magnetometer conducted the magnetic measurements. The uneven variations in the magnetic properties are explained based on Neel's two‐sublattice model.

Bis(glycinium) oxalate: effect of deuteration, single crystal neutron diffraction and Raman spectroscopic studies

AbstractThe crystal structure of bis(glycinium) oxalate (BGO) is stabilized by a very strong O–H..O hydrogen bond apart from N–H…O and C-H…O hydrogen bonds. To probe the effect of deuteration on these hydrogen bonds, fully deuterated (FDBGO), C-deuterated(CDBGO), and N-deuterated bis(glycinium) oxalate (NDBGO) crystals were grown. Single crystal neutron diffraction and Raman spectroscopic studies were carried out. It was found from neutron diffraction studies that the O…O distance of the O–H…O hydrogen bond reduced on deuteration showing an inverse Ubbelohde effect. The neutron diffraction and Raman spectroscopic studies also revealed partial deuteration. The DSC studies showed no phase transition. Variation of the melting point amongst the four crystals was in a very small range from 151 to 158 °C.

X-ray diffraction and Raman spectroscopy studies of Ga-Ge-Te alloys

The structure and vibrational properties of glassy Ge19Te81 and Ga7.9Ge11.5Te80.6 alloys were studied using X-ray diffraction and Raman spectroscopy. The amorphous nature of the obtained alloys was confirmed by the experimental X-ray diffraction patterns. The latter were used for calculating radial distribution functions. Such calculations gave the positions of the nearest-neighbour peak r1 – 2.65 Å and second nearest-neighbour peak r2 – 4.31 and 4.44 Å. The obtained r1 values are in good agreement with the known from literature Ge-Te and Ga-Te bond lengths. Similar r1 values were also observed for Ga-Ge-Te glasses of different compositions. The r2/r1 values of 1.63 and 1.68 are close to the typical value for a regular tetrahedron structure. The observed bands in the Raman spectra of the studied Ga-Ge-Te samples show that such glasses contain different nanophases. The Raman spectra may be interpreted in terms of vibrational modes of Ga-Te and Ge-Te binary glasses and films.

Raman spectroscopy study of the role of dispersion and interfaces in the improvement of the mechanical properties of epoxy-TiO2 composites

Raman spectroscopy study of the role of dispersion and interfaces in the improvement of the mechanical properties of epoxy-TiO2 composites

Investigation on Crystallization of CaO‐Al2O3‐B2O3‐BaO Slag Using Differential Scanning Calorimeter and In Situ High‐Temperature Raman Spectroscopy

CaO‐Al2O3‐B2O3‐based slag is among the most promising “nonreactive” mold fluxes for continuous casting of high‐aluminum steel. However, CaO‐Al2O3‐B2O3‐based slag system exhibits a stronger crystallization ability compared to traditional mold fluxes. Herein, calcium oxide in CaO‐Al2O3‐10%B2O3 slag is partially replaced by the same mass of barium oxide (5 and 10 mass%) to adjust the crystallization ability. The crystallization of glassy slags is then investigated using a differential scanning calorimeter and their crystallization kinetics are analyzed using the Matusita–Sakka model. The structural evolution of glassy slags from room temperature to 1200 °C is also investigated using in situ Raman spectroscopy. The kinetic analysis shows that the crystallization process of CaO‐Al2O3‐B2O3‐BaO glassy slags follows the surface crystallization mechanism. The predominant crystalline products are calcium monoaluminate (CaAl2O4) and calcium borate (Ca3(BO3)2). The partial replacement of calcium oxide by barium oxide inhibits the growth of CaAl2O4 in the slag by increasing the activation energy of crystal growth. The high‐temperature Raman spectroscopy study shows that the band between 700 and 900 cm−1 gets weaker relative to the band between 450 and 650 cm−1 at high temperatures. This indicates the strengthening of bending vibration of Al‐O‐Al, which is consistent with the precipitation of CaAl2O4 with full oxygen bridging.

Genetic Type and Formation Evolution of Mantle-Derived Olivine in Ultramafic Xenolith of Damaping Basalt, Northern North China Block

Olivine in deep-seated ultramafic xenoliths beneath the North China Block serves as a crucial proxy for decoding the compositions, properties, and evolution of the lithospheric mantle. Here, we conduct an investigation on olivine (including gem-grade) hosted in ultramafic xenoliths from Damaping basalt in the northern part of the North China Block. This contribution presents the results from petrographic, Raman spectroscopic, and major and trace elemental studies of olivine, with the aim of characterising the formation environment and genetic type of the olivine. The analysed olivine samples are characterised by high Mg# values (close to 91%) possessing refractory to fertile features and doublet bands with unit Raman spectra beams of 822 and 853 cm−1, which are indicative of a forsterite signature. Major and trace geochemistry of olivine indicates the presence of mantle xenolith olivine. All the analytical olivine assays ≤0.1 wt % CaO, ~40 wt % SiO2, and ≤0.05 wt % Al2O3. Furthermore, olivine displays significantly different concentrations of Ti, Y, Sc, V, Co, and Ni. The Ni/Co values in olivine range from 21.21 to 22.98, indicating that the crystallisation differentiation of basic magma relates to oceanic crust recycling. The V/Sc values in mantle/xenolith olivine vary from 0.54 to 2.64, indicating a more oxidised state of the mantle. Rare earth element (REE) patterns show that the LREEs and HREEs of olivine host obviously differentiated characteristics. The HREE enrichments of olivine and the LREE depletion of clinopyroxene further assert that the mantle in the Damaping area underwent partial melting. The wide variations of Mg# values in olivine and the Cr# values in clinopyroxene, along with major element geochemistry indicate transitional characteristics of different peridotite xenoliths. This is possibly indicative of a newly accreted lithospheric mantle interaction with an old lithospheric mantle at the time of the basaltic eruption during the Paleozoic to Cenozoic.

Spectrometers of Neutrons and Fast Atoms of Tokamak Thermonuclear Plasma Based on CVD Synthesized Diamond Single-Crystal Films

High radiation resistance, chemical inertness, the ability to operate at elevated temperatures, high mobility and efficiency of charge-carrier collection are important properties of diamond for designing detectors and spectrometers of ionizing radiation. Currently, diagnostics of neutrons and neutral particle fluxes based on diamond detectors for the ITER thermonuclear reactor are justified and developed. This work presents the results of a Raman spectroscopy and photoluminescence spectroscopy study of the electronic quality of synthesized epitaxial diamond films obtained by vapor deposition in a hydrogen and methane mixture in the ARDIS reactor on boron-doped single-crystal diamond substrates. To confirm their electronic quality, detectors have been made from films selected by spectrometric methods and the charge collection efficiency and energy resolution have been measured when irradiated with alpha particles from a 241Am source and 14.7 MeV fast neutrons from the ING-07T2 neutron generator.

Highly efficient iodine capture and selective adsorption and removal of cationic dyes by using a copper-based coordination polymer decorated over graphene oxide and carbon nanotubes

This study focuses on synthesizing hybrid nanocomposites (HNCs) through a one-step solvothermal method, combining highly crystalline and evenly dispersed copper-based coordination polymer (Cu-CP), graphene oxide (GO), and carbon nanotubes (CNTs). Extensive characterization using elemental analysis, SEM, TEM, EDX, XRD, FT-IR, Raman spectroscopy, TGA, and crystallographic studies confirm the properties of the nanocomposites, with PXRD investigation supporting their clear crystalline structure. Morphological and elemental studies reveal effective adsorption of copper-benzoic acid-containing Cu-CP onto GO and CNT substrates. The synthesized nanocomposites exhibit superior adsorption capacity for iodine (I2), a model radioactive pollutant, attributed to decreased CP size and larger surface area. The strong affinity for I2 arises from various interactions, including conjugated π-electron aromatic systems and halogen bonds. Cu-CP, Cu-CP@GO, and Cu-CP@CNT adsorbents efficiently extract toxic iodine from hexane solution, achieving a substantial capture capacity of 347.85 mg/g over 24 h. In the vapor phase, Cu-CP@GO exhibits an even higher capacity (951.52 mg/g within 25 h). Moreover, the application of Cu-CP, Cu-CP@GO, and Cu-CP@CNT in environmental protection showcases their efficacy in removing cationic and anionic dyes, particularly highlighting remarkable cationic dye selectivity through cation-π and π-π interactions. This research underscores the promising potential of these HNCs in addressing environmental challenges and pollutant remediation.

Cation Effect on the Product Selectivity of Electrochemical CO Reduction

Renewable electricity-powered reduction of CO2 (CO2R) is a promising route to upgrade CO2 to ethylene, an industrial feedstock in high demand. Compared with direct CO2 electroreduction to ethylene, CO2-CO-C2H4 tandem electrolysis is more carbon efficient, circumventing CO2 crossover and carbonate formation. However, current CO electroreduction produces a mixture of multi-carbon products (ethylene, ethanol, acetate, and propanol), and the mechanism underlying this dispersion of selectivity remains unclear.We studied the role of the microenvironment of the electrode in selectivity among C2+ products, and hypothesized that destabilizing the oxygen-containing intermediates would direct the reaction pathway toward the sole oxygen-free C2+ product, ethylene. When we explore the cations in electrolyte, we find the one with the most robust hydration shell (Li) promotes ethylene production, among C2+ products, compared to weakly hydrated cations (e.g. K). This is a distinctive trend compared to studies of activity that found reverse cation trend in jc2+. A combined study of operando Raman spectroscopy, MD simulation, and DFT calculation suggests that the strongly hydrated Li+ on the electrode surface has the greatest H2O-Ointermediate interaction and the least cation-Ointermediate interaction. This increases the difference in activation energy of the selectivity-determining step between ethylene pathway and oxygenates pathway, and hence leads to the preference of Li for hydrocarbons over oxygenates. Figure 1

(Keynote) Key Intermediates and Cu Active Sites for the Electrocatalytic Reduction of CO2 to Ethylene and Ethanol

Electrocatalytic reduction of CO2 (CO2RR) to multi-carbon products is a promising technology to store intermittent renewable electricity into high added value chemicals and close the carbon cycle. Its industrial scalability requires electrocatalysts to be highly selective to certain products, such as ethylene or ethanol. However, a substantial knowledge gap prevents the design of tailor-made materials, as the properties ruling the catalysts selectivity remain elusive. Here, I will describe how the findings from a combined in-situ surface-enhanced Raman spectroscopy and density functional theory study on electrochemically-roughened Cu foil electrocatalysts can be used to unveil the reaction scheme for CO2RR to C2+ products under potentiostatic conditions. In particular, ethylene generation occurs when *OC-CO(H) dimers form via CO coupling on undercoordinated Cu sites. The ethanol route opens up only in the presence of highly compressed and distorted Cu domains via the crucial intermediate *OCHCH2.Moreover, although it is known that subjecting copper to short anodic pulses during CO2RR improves both, the activity and the selectivity towards hydrocarbons and alcohols, the nature of the active sites is still unclear. To address this issue, the final state of an electrochemically treated Cu(100) surface was resolved by a combination of spectroscopy, microscopy and diffraction methods applied concurrently. The evolution of the morphology, chemical state and crystal structure of Cu(100) exposed to potential pulses during CO2RR has served to shed light into the nature of the active sites formed under dynamic reaction conditions. In particular, anodic pulses, which enhance the ethylene and ethanol production, favor the formation of (n10) facets. Furthermore, pulsing between specific anodic and cathodic potentials during CO2RR also leads to the stabilization of Cu oxide species that are located either at the surface or directly below ultrathin metallic Cu layers, depending on the nature of the pulse potential. The latter is key for the enhanced C2+ product selectivity obtained during pulsed CO2RR.Finally, by identifying and tracking the critical intermediates and specific actives sites, our work provides guidelines to selectively decouple different products on rationally designed catalysts.