Raman Spectra Of Different Samples Research Articles

Gemological and Chemical Characterization of Gem-Grade Peridot from Yiqisong, Jilin Province

Peridot has a long history and is deeply loved by people for its unique olive-green color. The Yiqisong peridot deposit in Jilin Province is a newly discovered peridot deposit that still deserves systematic research. In this study, gemological and chemical analyses of thirty-three Yiqisong peridot samples were carried out to investigate the gemological characteristics, as well as the mantle properties and formation conditions of the Yiqisong. In addition, we identified gemological differences in peridot between Yiqisong, Tanzania, and Arizona. The Yiqisong peridot samples have typical peridot gemological characteristics. The UV–visible spectrum indicated that Fe is the chromogenic element. The infrared spectra and Raman spectra of different samples are consistent, which indicates that the Yiqisong peridot belongs to forsterite. The contents of Ni and V in Yiqisong peridot are generally low, distinguishing it from peridot found in Tanzania and Arizona. The major and trace elements of samples show that the Yiqisong peridot is derived from the spinel lherzolite xenoliths with the P–T formation conditions of 813–1087 °C and 21–22 kbar. The Yisqisong peridot samples have relatively high Fo values (up to 91.6), supporting their origin from a moderate refractory lithosphere mantle. Therefore, this study provides gemological, mineralogical, and chemical evidence that fills the research gap in peridot deposit studies and lays the foundation for follow-up investigations of gem-grade peridot deposits.

2H-MoS 2 Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

2H-MoS ₂ Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

Detection of carbonate, phosphate minerals and cyanobacteria in rock from the Tomtor deposit, Russia, by Raman spectroscopy

Samples of rock from the Tomtor Nb - REE (rare-earth elements) deposit (Russia) have been investigated by Raman micro-spectroscopy using visible 532 nm wavelength excitation. Raman spectra of different samples of this rock confirm their composition as calcites and other carbonates such as rhodochrosite, and mixed solid solution phases (Ca, Mn, Fe, Mg, Ba, Sr, REE)(CO3). An association between cyanobacteria and the apatite crystals has been noted Cyanobacteria exhibited Raman modes at 1520–1517 cm−1 located in the double bonds of the central part of the polyene chain of carotenoids. A slight shift of this mode in the apatite-containing samples are dependent upon the compositions of carotenoids, the ratio of the rare earth elements adsorbed by cyanobacteria as well as their interaction with the environment. Laser-induced photoluminescence of REE and Mn+2, obtained as an analytical artifact in the Raman spectra, has been observed in most cases with significant spectral intensity. The luminescence emission of Mn 2+, Sm3+, Eu 3+, Pr3+, Ho3+, Er 3+ in the spectra of the apatite-containing samples obtained with 532 nm excitation can be attributed both to apatite and to other mineral phases with a low concentration which contain these elemental ions. The results obtained in this study allowed us to confirm that the biogenic presence of the cyanobacterial mat had a significant impact on the formation of the unique Nb-REE Tomtor deposit.

Ultrastructure and Raman Spectral Characteristics of Two Kinds of Acute Myeloid Leukemia Cells

To investigate the Raman spectral characteristics of leukemia cells from 4 patients with acute promyelocytic leukemia (M3) and 3 patients with acute monoblastic leukemia (M5), establish a novel Raman label-free method to distinguish 2 kinds of acute myeloid leukemia cells so as to provide basis for clinical research. Leukemia cells were collected from bone marrow of above-mentioned patients. Raman spectra were acquired by Horiba Xplora Raman spectrometer and Raman spectra of 30-50 cells from each patient were recorded. The diagnostic model was established according to principle component analysis (PCA), discriminant function analysis (DFA) and cluster analysis, and the spectra of leukemia cells from 7 patients were analyzed and classified. Characteristics of Raman spectra were analyzed combining with ultrastructure of leukemia cells. There were significant differences between Raman spectra of 2 kinds of leukemia cells. Compared with acute monoblastic leukemia cells, the spectra of acute promyelocytic leukemia cells showed stronger peaks in 622, 643, 757, 852, 1003, 1033, 1117, 1157, 1173, 1208, 1340, 1551, 1581 cm-1. The diagnostic models established by PCA-DFA and cluster analysis could successfully classify these Raman spectra of different samples with a high accuracy of 100% (233/233). The model was evaluated by "Leave-one-out" cross-validation and reached a high accuracy of 97% (226/233). The level of macromolecules of M3 cells is higher than that of M5. The diagnostic models established by PCA-DFA can classify these Raman spectra of different cells with a high accuracy. Raman spectra shows consistent result with ultrastructure by TEM.

Raman spectral characteristics of oral squamous cell carcinoma, epithelial dysplasia and normal mucosa

To investigate the Raman spectral characteristics of oral squamous cell carcinoma, high-grade epithelial dysplasia and normal mucosa. Fifty- six fresh samples of oral carcinoma, 50 of high-grade epithelial dysplasia and 32 of normal mucosa were collected. The i-Raman spectrometer with an optical fiber tube was applied to acquire Raman spectrum. The diagnostic model established by principle component analysis (PCA) and discriminant function analysis (DFA) was used to analyze and classify the spectra of different samples. There were significant differences among the Raman spectra of these samples. Compared with the spectra of normal mucosa, the spectra of oral carcinoma and dysplasia showed strong peaks which were contributed to nucleic acids, proteins and lipids. The diagnostic models established by PCA-DFA could successfully classify these Raman spectra of different samples with a high accuracy of 96.4% (133/138). The model was evaluated by 'Leave one out' cross-validation and reached a high accuracy of 92.8% (128/138). The proliferation and metabolism of oral squamous cell carcinoma and epithelial high-grade dysplasia are more active than normal mucosa. The diagnostic models established by PCA-DFA can classify these Raman spectra of different samples with a high accuracy.

Comment on vibrational spectral investigation on xanthine and its derivatives—theophylline, caffeine and theobromine

these pharmacologically active molecules. However, some care should be taken in the sample preparation, since sample handling may affect the water content of samples. This is a very relevant issue, since it has been shown that water causes pseudopolymorphic transformations on both theophylline and caffeine, which affect their bioavailability and stability [2–5]. Both caffeine and theophylline can be crystallized under the dehydrated [6,7] and monohydrated forms [6,8]. The dehydrated form can be obtained commercially, while monohydrated forms are currently prepared from recrystallization in water. However, our studies show that anhydrous crystals can turn into the monohydrated ones by simple exposure to the humidity from surrounding atmosphere over a few days. A similar effect has already been described for -cyclodextrin [9] and glucose [10], for instance. The dehydrated and monohydrated forms have quite difcorrespond to two different samples. In fact, the FT-IR spectrum (Fig. 3 [1], top) clearly refers to the monohydrated form, while the Raman spectrum (Fig. 3 [1], bottom) corresponds to the anhydrous sample. Since the authors state that the samples had been obtained commercially with high grade purity and used as such [1], it can be assumed that the Raman spectra was obtained from a “fresh” sample, while the sample for FT-IR was left in contact with atmosphere humidity for a few days before recording the spectrum. The description of IR and Raman spectra of different samples as “vibrational spectra of theophylline”, and their use as such, has two main effects: it can be misleading for future readers and it has been misleading to the authors themselves. In fact, there are several relevant changes in the positions and intensities of the vibrational bands from one form to another, which were not detected by the authors. The assignments present in Table 4 of [1], as well as the proposed correspon-

Raman characterization of 0.4 nm single-wall carbon nanotubes using the full-symmetry line group

Raman spectra of single-wall carbon nanotubes produced in the channels of zeolite AFI single crystals have been analyzed in the light of the full symmetry group, the line group. The phonon dispersion curves of the tubes (5,0), (3,3), and (4,2) are calculated based on the lattice dynamical model and the phonon branches are assigned to their quantum numbers (irreducible representations). The structures of Raman spectra of different samples are reproduced well by the density of states of relevant Raman-active phonons. The result is useful to evaluate the contents of these tubes in real crystals where the contents are not well defined before.

Resonant Raman characterisation of ultra-thin nano-protective carbon layers for magnetic storage devices

Carbon thin films are very important as protective coatings for a wide range of applications such as magnetic storage devices. The key parameter of interest is the sp 3 fraction, since it controls the mechanical properties of the film. Visible Raman spectroscopy is a very popular technique to determine the carbon bonding. However, the visible Raman spectra mainly depend on the configuration and clustering of the sp 2 sites. This can result in the Raman spectra of different samples looking similar albeit having a different structure. Thus, visible Raman alone cannot be used to derive the sp 3 content. Here we monitor the carbon bonding by using a combined study of Raman spectra taken at two wavelengths (514 and 244 nm). We show how the G peak dispersion is a very useful parameter to investigate the carbon samples and we endorse it as a production-line characterisation tool. The dispersion is proportional to the degree of disorder, thus making it possible to distinguish between graphitic and diamond-like carbon.

Raman spectra of submicron amorphous carbon grains and mixtures of polycyclic aromatic hydrocarbons

We present here Raman spectra of different samples of materials, potentially candidates of interstellar dust, namely amorphous carbon submicron particles and polycyclic aromatic hydrocarbon collections (PAH). The carbon particles show spectra characterized by two peaks, falling respectively at 1365 cm −1 and 1590 cm −1, while PAH spectra seem to be characterized by a single line at 1590 cm −1.These preliminary results confirm that PAH collections alone cannot account for the astronomical unidentified infrared bands (UIR), while mixtures containing also hydrogenated amorphous carbon (HAC) produce a better match.