scholarly journals Distinguishing ice β-XV from deep glassy ice VI: Raman spectroscopy

2019 ◽  
Vol 21 (28) ◽  
pp. 15452-15462 ◽  
Author(s):  
Alexander V. Thoeny ◽  
Tobias M. Gasser ◽  
Thomas Loerting
Keyword(s):  
Raman Spectroscopy ◽  
Raman Band

Evidence for the existence of D2O-ice β-XV is given by the observation of its librational Raman band at 380 cm−1.

ARSENIC-INDUCED DOWNSHIFT OF RAMAN BAND POSITIONS FOR PYRITE

2020 ◽  
Vol 115 (7) ◽  
pp. 1589-1600
Author(s):  
Qiaoqiao Zhu ◽  
Nigel J. Cook ◽  
Guiqing Xie ◽  
Benjamin P. Wade ◽  
Cristiana L. Ciobanu
Keyword(s):  
Raman Spectroscopy ◽  
Environmental Science ◽  
Raman Band ◽  
Eastern China ◽  
Chemical Properties ◽  
Minor Element ◽  
Minor Elements ◽  
Band Position ◽  
Wide Range ◽  
The Impact

Abstract Pyrite commonly incorporates a wide range of trace and minor elements, which in turn may modify some of the mineral’s physical and chemical properties. Published band position data for the Raman spectra of pyrite show a wide variation, and the relationship between band position and the trace/minor element incorporation in pyrite is poorly constrained until now. This prompted a case study on pyrite with varying As content from the Shizilishan Sr-(Pb-Zn) deposit, eastern China, combining electron probe microanalysis with Raman spectroscopy. Results show a significant correlation, with a major downshift (~10 cm–1) of the positions of all three Raman bands with increase of As content from below 0.05 to 4.89 wt % in pyrite. This phenomenon is attributed to increased bond lengths and local distortions within an expanded pyrite crystal structure. Results highlight the potential that Raman spectroscopy offers to estimate the contents of trace/minor elements—especially As—in pyrite. Given that substitution of As into pyrite often facilitates co-incorporation of both economically useful (Au) and environmentally significant elements (Hg and Tl), Raman methodology could provide valuable, rapid assessment of pyrite chemistry in both gold deposit exploration and environmental science, although the impact of laser heating and mechanical polishing needs to be avoided or effectively reduced. Raman spectroscopy may also find a valuable future role within semiautomated multispectral analytical platforms that can generate close- to-real-time geologic information on freshly drilled core directly at the drill site or in outcrop.

Raman Spectroscopy: An Exploratory Study to Identify Post-Radiation Cell Survival

2020 ◽  
Vol 74 (5) ◽  
pp. 553-562
Author(s):  
Kshama Pansare ◽  
Saurav Raj Singh ◽  
Venkatavaradhan Chakravarthy ◽  
Neha Gupta ◽  
Arti Hole ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Cell Viability ◽  
Cell Survival ◽  
Cell Line ◽  
Cell Lines ◽  
Clonogenic Assay ◽  
Early Stage ◽  
Raman Band ◽  
Breast Adenocarcinoma ◽  
Linear Discriminant

Resistance to radiotherapy has been an impediment in the treatment of cancer, and the inability to detect it at an early stage further exacerbates the prognosis. We have assessed the feasibility of Raman spectroscopy as a rapid assay for predicting radiosensitivity of cancer cells in comparison to the conventional biological assays. Cell lines derived from breast adenocarcinoma (MCF7), gingivobuccal squamous cell carcinoma (ITOC-03), and human embryonic kidney (HEK293) were subjected to varying doses of ionizing radiation. Cell viability of irradiated cells was assessed at different time points using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and Raman spectroscopy, and colony-forming capability was evaluated by clonogenic assay. Radiosensitivity observed using MTT assay was limited by the finding of similar cell viability in all the three cell lines 24 h post-irradiation. However, cell survival assessed using clonogenic assay and principal component linear discriminant analysis (PC-LDA) classification of Raman spectra showed correlating patterns. Irradiated cells showed loss of nucleic acid features and enhancement of 750 cm−1 peak probably attributing to resonance Raman band of cytochromes in all three cell lines. PC-LDA analysis affirmed MCF7 to be a radioresistant cell line as compared to ITOC-03 and HEK293 to be the most radiosensitive cell line. Raman spectroscopy is shown to be a rapid and alternative assay for identification of radiosensitivity as compared to the gold standard clonogenic assay.

Corroboration of Structural Properties of Dy2O3-TiO2 Nanocomposites through X-Ray Diffraction and Raman Spectroscopy

2017 ◽  
Vol 17 ◽  
pp. 127-130
Author(s):  
J. Dhanalakshmi ◽  
D. Pathinettam Padiyan
Keyword(s):  
Raman Spectroscopy ◽  
Crystallite Size ◽  
Structural Properties ◽  
Oxygen Vacancies ◽  
Raman Band ◽  
Anatase Phase ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Percentage

Dy2O3-TiO2 nanocomposites with different weight percentage (0, 2, 4, 8 & 10)Dy were synthesized bysol-gel method and named as 0DT, 2DT, 4DT, 6DT, 8DT and 10DT. The structural properties of these nanocomposites are characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD results show that Dy2O3-TiO2 nanocomposites have anatase phase with tetragonal structure. The average crystallite size of the Dy2O3-TiO2 nanocomposites lies between 10 to 18 nm.Coupling of Dy with TiO2 shifts the Raman band to higher wavenumber side indicating the creation of oxygen vacancies in the TiO2 lattice.

Microcomputer Controlled Flash Photometry with Submicrosecond Resolution and Raman Spectroscopy

1983 ◽  
Vol 37 (2) ◽  
pp. 203-207 ◽  
Author(s):  
Zvi Meiri ◽  
Yaakov Berezin ◽  
Avraham Shemesh ◽  
Benjamin Ehrenberg
Keyword(s):  
Raman Spectroscopy ◽  
Data Collection ◽  
Fluorescence Spectroscopy ◽  
Time Resolution ◽  
Raman Band ◽  
Photon Counting ◽  
Direct Memory Access ◽  
Memory Access ◽  
Access Mode ◽  
Light Flashes

The interfacing of two spectrophotometric systems to an Apple II microcomputer is described. The first is a flash photometric setup in which light flashes are formed either with a chopper wheel, or with an acousto-optic modulator which is activated by the microcomputer. Spectroscopic transients are monitored with a time resolution as short as 250 ns, by counting photon pulses into the computer's memory in the fast direct memory access mode. The formation half-times of the M412 intermediate in the photocycle of bacteriorhodopsin were measured in H2O and in D2O using the characteristic Raman band of this species, and are 68 ± 2 and 300 ± 5 μs, respectively. A microcomputer-controlled Raman spectrometer, in which the Apple II is interfaced to a Spex monochromator and the photon counting electronics, is also described. These microcomputer-controlled configurations provide simple and inexpensive setups for data collection in flash photometry and Raman and fluorescence spectroscopy.

Revealing microstructural properties of shocked and tectonically deformed zircon from the Vredefort impact structure: Raman spectroscopy combined with SEM microanalyses

2021 ◽  
Author(s):  
Elizaveta Kovaleva ◽  
Dmitry A. Zamyatin
Keyword(s):  
Raman Spectroscopy ◽  
Raman Band ◽  
Impact Structure ◽  
Chemical Mapping ◽  
Deformation Bands ◽  
Electron Backscattered Diffraction ◽  
Granite Sample ◽  
Deformation Features ◽  
Ebsd Technique ◽  
Deformation Patterns

ABSTRACT Finite deformation patterns of accessory phases can indicate the tectonic regime and deformation history of the host rocks and geological units. In this study, tectonically deformed, seismically deformed, and shocked zircon grains from a granite sample from the core of the Vredefort impact structure were analyzed in situ, using a combination of Raman spectroscopy, backscatter electron (BSE) imaging, electron backscattered diffraction (EBSD) mapping, electron probe microanalyses (EPMA), energy-dispersive X-ray spectroscopy (EDS) qualitative chemical mapping, and cathodoluminescence (CL) imaging. We aimed to reveal the effects of marginal grain-size reduction, planar deformation bands (PDBs), and shock microtwins on the crystal structure and microchemistry of zircon. Deformation patterns such as PDBs, microtwins, and subgrains did not show any significant effect on zircon crystallinity/metamictization degree or on the CL signature. However, the ratio of Raman band intensities B1g (1008 cm–1) to Eg (356 cm–1) slightly decreased within domains with low misorientation. The ratio values were affected in shocked grains, particularly in twinned domains with high misorientation. B1g/Eg ratio mapping combined with metamictization degree mapping (full width at half maximum of B1g peak) suggest the presence of shock deformation features in zircon; however, due to the lower spatial resolution of the method, they must be used in combination with the EBSD technique. Additionally, we discovered anatase, quartz, goethite, calcite, and hematite micro-inclusions in the studied zircon grains, with quartz and anatase specifically being associated with strongly deformed domains of shocked zircon crystals.

Investigation of defects in crystalline silicon solar cells by confocal Raman spectroscopy

2018 ◽  
Vol 29 (8) ◽  
pp. 1525-1533 ◽  
Author(s):  
Gilbert O Osayemwenre ◽  
Edson L Meyer ◽  
Raymond Taziwa
Keyword(s):  
Raman Spectroscopy ◽  
Solar Cells ◽  
Solar Cell ◽  
Stress Level ◽  
Crystalline Silicon ◽  
Raman Band ◽  
Reverse Direction ◽  
Confocal Raman Spectroscopy ◽  
Confocal Raman ◽  
Solar Material

Defects in solar cells can be caused during processing or through a benign event like a falling leaf when operating in an outdoor system. Shading caused by such a leaf can result in the cell operating in the reverse direction and ultimately in hotspot formation, which in turn can cause the entire cell to breakdown and essentially become a power dissipator rather than a producer. More often than not, this reverse biasing of the cell will enhance the effect of any inherent defect. In this study, poly-Si cells were reverse biased to enhance the effect of their inherent defect. These defects were then analysed using non-destructive confocal Raman spectroscopy, since this technique allows us to observe small defects in cells/material using the intensity of the transverse optic bands. The intensity of defect-induced Raman band has a direct relationship with the observed morphological defects of the reverse biased cell. The quality of the active layer was also investigated; this includes the chemical composition and the stress level which can be found through the single spectrum bandwidth. The efficiency of solar material depends on the absorption capability of the solar material, while the optical and the electrical properties to a large extent determine the absorption capability of solar cell. However, its structure, defect and stress level can offset the total optical and electronic properties. The present study reveals defect in micro-level and the stress induced in the affected region of the solar cell. Confocal Raman is suitable for characterising stresses in relation to microstructure, defect level as well as the manufacturer-induced defect in the substrate.

Deformation Mechanisms in Natural Polymer Fibers and Composites

2001 ◽  
Vol 711 ◽  
Author(s):  
Robert J. Young ◽  
Stephen J. Eichhorn ◽  
J. Sirichaisit ◽  
Victoria L. Brookes
Keyword(s):  
Raman Spectroscopy ◽  
Tensile Deformation ◽  
Raman Band ◽  
Amorphous Structure ◽  
Polymer Chains ◽  
Polymer Fibers ◽  
Band Shift ◽  
Hemp Fibers ◽  
The Relationship ◽  
Molecular Deformation

ABSTRACTThe molecular deformation of both silkworm (Bombyx mori) and spider dragline (Nephila edulis) silks has been studied using a combination of mechanical testing and Raman spectroscopy. It was found that both materials have well-defined Raman spectra and that some of the bands in the spectra shift to lower wavenumber under the action of tensile stress or strain. The band shift was linearly dependent upon stress for both types of silk fiber for the 1085/1095 cm-1 band. This observation provides a unique insight into the effect of tensile deformation upon molecular structure and the relationship between structure and mechanical properties. The measurement of micromechanical deformation within samples of wood, flax and hemp fibers using Raman spectroscopy is also reported. Upon tensile deformation of the samples it was found that the characteristic Raman peak for cellulose, located at 1095 cm-1, shifted towards a lower wavenumber, indicating that the polymer chains within the cellulose were also being deformed. The magnitude of the shift with strain was found to be similar for all samples. No shift occurred of the peak that is characteristic of the non-load-bearing lignin (1600 cm-1) in the wood samples due to its amorphous structure. The similarities between the Raman band shifts in silk and cellulose are discussed.

Thermodynamic Analysis of Reaction Equilibria in Ionic and Molecular Liquid Systems by High-Temperature Raman Spectroscopy

2009 ◽  
Vol 63 (9) ◽  
pp. 1050-1056
Author(s):  
Angelos G. Kalampounias ◽  
Soghomon Boghosian
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Complex Formation ◽  
Equilibrium Constant ◽  
Thermodynamic Analysis ◽  
Raman Band ◽  
Thermal Dissociation ◽  
Temperature Dependent ◽  
Liquid Systems ◽  
Molten Phase

A formalism for correlating relative Raman band intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of reaction equilibria in solution is derived. The proposed method is used for studying: (1) the thermal dissociation of molten KHSO4 in the temperature range 240–450 °C; (2) the dinuclear complex formation in molten TaCl5–AlCl3 mixtures at temperatures between 125 and 235 °C. The experimental and calculational procedures for exploiting the temperature-dependent Raman band intensities in the molten phase as well as (if applicable) in the vapors thereof are described and used for determining the enthalpy of the equilibria: (1) 2HSO4−( l) ↔ S2O72–( l) + H2O( g), Δ H0 = 64.9 ± 2.9 kJ mol−1; and (2) 1/2Ta2Cl10( l) + 1/2Al2Cl6( l) ↔ TaAlCl8( l), Δ H0 = −12.1 £ 1.5 kJ mol−1.

Texture and Phases in Oxide Films on Zr-Nb Alloys

1994 ◽  
Vol 343 ◽  
Author(s):  
Y. P. Lin ◽  
O. T. Woo ◽  
D. J. Lockwood
Keyword(s):  
Raman Spectroscopy ◽  
Volume Fraction ◽  
Raman Band ◽  
Oxide Films ◽  
Cubic Phase ◽  
Columnar Grains ◽  
Beam Orientation ◽  
Cubic Structure ◽  
Low Volume ◽  
Raman Response

ABSTRACTOxide films, 0.2-2.0 μm in thickness on Zr-2.5Nb and 11 μm thick on Zr-20Nb alloys, formed in steam at 673 K, have been examined using TEM, XRD and Raman spectroscopy. Columnar grains of mostly monoclinic Zr02 in oxide films on Zr-2.5Nb exhibit a dual texture: a fibre mode with an axis close to the 102m pole and a [001]m growth mode with an orientation relationship [100]m // [4510]α and (010)m // (0001)α with the α-Zr metal. In both modes, “tetragonal” (and/or cubic) ZrO2 was present. Raman spectroscopy differentiated two non-cubic “tetragonal” forms of ZrOz within the [001]m growth texture. In thin oxides (0.5 μm or less), this corresponds to the tetragonal ZrO2 observed in ceramic zirconia and is characterised by a Raman band near 260 cm−1. The 278 and related 438 cm−1 Raman bands observed here in some oxide films (and in other Zr corrosion oxides) are attributed to a separate, non-cubic phase structurally related to the tetragonal ZrO2. The intensities of the 278 and 438 cm−1 bands are dependent not only on the amount of this modified-tetragonal phase but also on the oxide texture (related to the metal texture) and the beam orientation. The lack of Raman response from the “tetragonal” ZrO2 within the fibre mode of texture indicates either a low volume fraction or a cubic-like structure. For oxide on Zr-20Nb, XRD and Raman spectroscopy show a mixture of monoclinic and “tetragonal” ZrO2; the Raman results indicate the “tetragonal” ZrO2 has a high crystal symmetry or nearly cubic structure.

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