Journal of Raman Spectroscopy最新文献

Layered perovskites AA′BO₄ are promising electrolyte materials for electrochemical devices as sources of renewable and distributed energy. Creation of new materials with target properties requires knowledge of their local structure. In this paper, the influence of the nature and concentration of dopants (Ca²⁺ and Sr²⁺) during isovalent doping in the layered perovskite BaLaInO₄ has been investigated for the first time. Doping was found to change the crystal symmetry from orthorhombic (space group Pbca) for the matrix BaLaInO₄ composition to tetragonal (space group I4/mmm) for the doped Ba_1 − xCa_xLaInO₄ and Ba_1 − xSr_xLaInO₄ compositions. Doping results in the redistribution of bond lengths and changes the tilt angle of In-containing polyhedra. These alterations in the crystal lattice increase the oxygen-ionic conductivity values up to 1–1.5 orders of magnitude.

Femtosecond chirped-probe-pulse (CPP) CARS technology has become a powerful tool for measuring complex high-temperature combustion temperatures due to its interference-free characteristics, high accuracy, and excellent time resolution. The experiment uses a specific energy-matching method to effectively separate the signal light from the background light and thus improve the accuracy of the measurement. The optimization was confirmed in the inner and outer flames of the butane Bunsen burner, with the best accuracy of 3.2% and 1.7% at 1385 and 1411 K, respectively. The two-dimensional temperature distribution at the outlet of the heat gun was experimentally measured using the aforementioned energy-matching method. The results show that the average accuracy can be below 2% at temperatures exceeding 700 K and that the temperature distribution corresponds to the nozzle structure at the air outlet. The experimental results demonstrate the successful acquisition of spatially resolved 2D temperature distributions under challenging high-temperature turbulent combustion conditions using femtosecond CPP CARS, providing valuable reference data for turbulent combustion studies.

Fluid and melt inclusions serve as invaluable micro-scale archives of geochemical processes, preserving snapshots of mineral-forming fluids and melts across a broad range of pressures and temperatures in natural environments. Their analysis provides critical insights into crystallization histories, metasomatic events, and volatile cycling in geological systems. However, the automated identification of minerals within these inclusions has long been hindered by spectral complexities arising from phase coexistence, host-mineral interference, and orientation-dependent Raman signatures. This study introduces the web-based tool Advanced spectRa Deconvolution Instrument (ArDI) (https://ardi.fmm.ru), which integrates fast search algorithms (Faiss), convolutional neural networks, and recursive spectral decomposition to analyze complex Raman spectra. Using pegmatitic quartz as a case study, we demonstrate that the method allows effective identification of minerals within fluid inclusions, e.g., sassolite and ramanite-(Rb), even when their spectra are integrated with host and other minerals. The developed approach unlocks new possibilities for nondestructive analysis of mineral assemblages in microscopic objects.

In this theoretical study, focusing on the single resonant Raman G mode, new details of Raman radiation from monolayer graphene are presented. The propagation direction of the emitted photon is discussed, explicitly considering the momenta of the incident photon, the scattered photon, and the phonon. It is demonstrated that graphene should be regarded as a quasi-two-dimensional system in light scattering phenomena, and the electron confined motion along the z-direction, perpendicular to the atomic monolayer plane, must be taken into account. It is established that the out-of-plane nature of the emitted photon arises from the uncertainty of the electron momentum along the z-direction. It is theoretically shown that at Raman G scattering, the wavenumber of the emitted iLO or iTO phonon is limited to a certain range, with boundaries determined by the crystal sizes and the wavenumber of the incident photon. Two-sided limitation of the Raman-active optical phonon wavenumber, in turn, restricts the propagation direction of the emitted photon. The developed approach is general and can also be applied to the analysis of other Raman lines of graphene.

Surface-enhanced Raman spectroscopy (SERS) is a rapid and sensitive method for ultra-trace analyte detection. The current work demonstrates the application of an array of Au-nanotriangles as a sensitive, efficient, and customized SERS substrate, manufactured via electron beam lithography on a silicon wafer. The Raman spectra of rhodamine 6G (R6G) at micromolar concentration have been accurately and efficiently detected to evaluate the SERS response of the proposed substrate. The suggested substrate also enables ultra-trace detection of the parasiticide leuco-malachite green (LMG) at nanomolar concentrations. It demonstrates exceptional repeatability and reproducibility of the SERS signal under examination, confirming the substantial resilience of the constructed substrate. The identification of the hazardous parasiticide LMG will assist healthcare professionals, since it is associated with several deleterious consequences in humans, including DNA damage, chromosomal mutations, and the potential development of tumors in vital organs such as the liver, thyroid, and bladder.

Surface-enhanced Raman spectroscopy (SERS) is a rapid and sensitive method for ultra-trace analyte detection. The current work demonstrates the application of an array of Au-nanotriangles as a sensitive, efficient, and customized SERS substrate, manufactured via electron beam lithography on a silicon wafer. The Raman spectra of rhodamine 6G (R6G) at micromolar concentration have been accurately and efficiently detected to evaluate the SERS response of the proposed substrate. The suggested substrate also enables ultra-trace detection of the parasiticide leuco-malachite green (LMG) at nanomolar concentrations. It demonstrates exceptional repeatability and reproducibility of the SERS signal under examination, confirming the substantial resilience of the constructed substrate. The identification of the hazardous parasiticide LMG will assist healthcare professionals, since it is associated with several deleterious consequences in humans, including DNA damage, chromosomal mutations, and the potential development of tumors in vital organs such as the liver, thyroid, and bladder.

The residues of crystal violet (CV) in shrimp were easily absorbed by biological tissues and caused serious damage to human health. In this study, doped TiO₂ SERS substrates were fabricated with three doping metals including Fe, Cu, and Co by sol-hydrothermal method. The SERS intensities reached the optimum at a Fe³⁺ doping ratio of 5% with probe molecules of 4-MBA and CV. The 5% Fe-TiO₂ SERS substrates for monitoring CV residues obtained the best performance with LOD of 0.016 ppm and 0.03 ppm for standard solutions and shrimp protein extract solutions, respectively. The results indicated suitable doping metals could effectively modulate the energy bands of the semiconductor and improve the charge transfer between the substrate and analyte for a stronger SERS signal. The study would enrich the SERS technique for the fast test of CV in the actual samples.

Molybdenum chalcogenides are one of the most studied layered materials. They have hexagonal symmetry in the single layer case as many other van der Waals materials. Thus, they can serve as a model for the analysis of many physical properties, in particular the phonon modes, the appearance of new low wave number modes when going from the single layer to the bulk, the existence of a flexural acoustic mode and the grouping of the optical modes into pairs whose difference comes from the interlayer coupling. In this work, to address some of these points, we have calculated the phonon dispersion of MoS$�{}_{�2�}$, MoSe$�{}_{�2�}$, and MoTe$�{}_{�2�}$ in bulk and in a single layer using Density Functional Perturbation Theory and discuss the evolution of the energy branches along the different directions of the Brillouin zone. The calculated values are in very good agreement with Raman data reported in the literature. We have also calculated the static and optical dielectric constants, as well as the reflectance, which has been compared with available infrared reflectance data available in the literature. Finally, we discuss the activity of the optical modes in the bulk and single layer case.