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Raman spectra

Cristina Márquez, M Isabel López, Itziar Ruisánchez, M Pilar Callao
Two data fusion strategies (high- and mid-level) combined with a multivariate classification approach (Soft Independent Modelling of Class Analogy, SIMCA) have been applied to take advantage of the synergistic effect of the information obtained from two spectroscopic techniques: FT-Raman and NIR. Mid-level data fusion consists of merging some of the previous selected variables from the spectra obtained from each spectroscopic technique and then applying the classification technique. High-level data fusion combines the SIMCA classification results obtained individually from each spectroscopic technique...
December 1, 2016: Talanta
Hongyang Su, Weidong Ruan, Shunsheng Ye, Yawen Liu, Huimin Sui, Zihui Li, Xiaoying Sun, Chengyan He, Bing Zhao
Potassium ions play pivotal roles in biological systems. A simple and effective Raman scattering-based protocol for the detection of physiological potassium ions level in human serum has been developed. We employed sodium cobaltinitrite, which can react with potassium to form potassium-sodium cobaltinitrite. Combining hydrophobic surface and the Raman scattering for potassium detection, highly reproducible Raman spectra of the potassium-sodium cobaltinitrite can be obtained with highly sensitivity. The characteristic Raman peak of potassium-sodium cobaltinitrite was used to distinguish it from other kinds of matter, and its intensity was used to monitor the amounts of potassium ions in human serum...
December 1, 2016: Talanta
Yunfei Tian, Peng Wu, Qin Liu, Xi Wu, Xiandeng Hou
Surface-enhanced Raman scattering (SERS) has been applied in a range of fields for its super high sensitivity which can even reach the single molecule level. But the quantification methods based on SERS still have some challenges such as stability, repeatability, and linearity at low concentrations. Here we propose a new quantification approach by using a total mapping scheme, and then add all the spectra together to obtain a final merged spectrum (a total SERS spectrum). The total SERS spectra were used to perform quantification analysis...
December 1, 2016: Talanta
B Hehlen, M Al-Sabbagh, A Al-Zein, J Hlinka
The fluctuations of electric polarization in a disordered ferroelectric substance, relaxor crystal PbMg_{1/3}Nb_{2/3}O_{3} (PMN), were studied using a nonlinear inelastic light-scattering technique, hyper-Raman scattering, within a 5-100  cm^{-1} spectral interval and in a broad temperature range from 20 to 900 K. The split ferroelectric mode reveals a local anisotropy of up to about 400 K. Spectral anomalies observed at higher temperatures are explained as due to avoided crossing of the single primary polar soft mode with a temperature-independent, nonpolar spectral feature near 45  cm^{-1}, known from Raman scattering...
October 7, 2016: Physical Review Letters
Shan Wang, Changmin Hou, Long Yuan, Mingyang Qu, Bo Zou, Dayong Lu
Perovskite structured rare-earth chromites are one of the most promising families of functional materials in solid oxide fuel cells, multiferroic materials, and sensors. Here, we report a mild hydrothermal method to synthesize DyCrO3 and HoCrO3 monodispersed single crystals. The synthesis conditions, crystal structure, Raman spectra and temperature- and field-dependent magnetic properties were studied. The two samples are indexed to the Pbnm space group. The shapes of the crystals are plates with a narrow particle size distribution in the range of 4-5 μm...
October 21, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Thitaphat Ngernsutivorakul, Cynthia M Cipolla, Colleen E Dugan, Shi Jin, Michael D Morris, Robert T Kennedy, Francis W L Esmonde-White
Fiber optics coupled to components such as lenses and mirrors have seen extensive use as probes for Raman and fluorescence measurements. Probes can be placed directly on or into a sample to allow for simplified and remote application of these optical techniques. The size and complexity of such probes however limits their application. We have used microfabrication in polydimethylsiloxane (PDMS) to create compact probes that are 0.5 mm thick by 1 mm wide. The miniature probes incorporate pre-aligned mirrors, lenses, and two fiber optic guides to allow separate input and output optical paths suitable for Raman and fluorescence spectroscopy measurements...
October 20, 2016: Analytical and Bioanalytical Chemistry
Justin M Gorham, William A Osborn, Jeremiah W Woodcock, Keana C K Scott, John M Heddleston, Angela R Hight Walker, Jeffrey W Gilman
To better assess risks associated with nano-enabled products including multiwalled carbon nanotubes (MWCNT) within polymer matrices, it is important to understand how MWCNT are dispersed throughout the composite. The current study presents a method which employs imaging X-ray photoelectron spectroscopy (XPS) to chemically detect spatially segregated MWCNT rich regions at an epoxy composites surface by exploiting differential charging. MWCNT do not charge due to high conductivity and have previously been shown to energetically separate from their insulating surroundings when characterized by XPS...
January 2016: Carbon
Aaron J Celestian, Caleb J Chappell, Melinda J Rucks, Pauline Norris
The ion exchange of yttrium, one of the five most critical rare-earth elements as outlined by the U.S. Department of Energy, into ETS-4 is a dynamic, multistep ion exchange process. The ion exchange process was followed using in situ time-resolved Raman spectroscopy, and the crystal structures of the pre-exchange and post-exchange forms were determined by single-crystal X-ray diffraction. In situ Raman spectroscopy is an ideal tool for this type of study, as it measures the spectral changes that are a result of molecular geometry changes at fast time intervals, even where symmetry and unit volume changes are minimally detected by X-ray diffraction...
October 19, 2016: Inorganic Chemistry
A K Sivadasan, Chirantan Singha, A Bhattacharyya, Sandip Dhara
The observation of interface (IF) phonon modes in the recorded Raman spectra of c-plane oriented [AlN/GaN]20 and [Al0.35Ga0.65N/Al0.55Ga0.45N]20 multi-quantum well (MQW) structures grown via plasma assisted molecular beam epitaxy is reported. The nominal shift in the IF phonon mode of E1 symmetry for [Al0.35Ga0.65N/Al0.55Ga0.45N]20 compared to that of the [AlN/GaN]20 MQW structure is understood on the basis of change in dielectric constants (εm) of the surrounding medium. The presence of buffer layers in [Al0...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Lixin Xia, Jing Wang, Caiqing Ma, Shiwei Wu, Peng Song
The vibrational spectra have been investigated for revealing the comprehensive structure of diferrocenyl-oligothienylene-vinylene complex, stimulated by the excellent experimental reports [group of Casado J. Am. Chem. Soc. 2012, 134, 12, 5675]. The IR and Raman spectra were simulated. It is found that the change of charge distribution and bond length are associated with the variation in the frequencies of specific vibration in infrared spectra for the neutral and radical oxidation states. The theoretical simulation of charge difference density indicate that charge transfer mechanism for neutral and dication states are significant different...
October 19, 2016: Scientific Reports
Ryan Stables, Graeme Clemens, Holly J Butler, Katherine M Ashton, Andrew Brodbelt, Timothy P Dawson, Leanne M Fullwood, Michael D Jenkinson, Matthew J Baker
Spectroscopic diagnostics have been shown to be an effective tool for the analysis and discrimination of disease states from human tissue. Furthermore, Raman spectroscopic probes are of particular interest as they allow for in vivo spectroscopic diagnostics, for tasks such as the identification of tumour margins during surgery. In this study, we investigate a feature-driven approach to the classification of metastatic brain cancer, glioblastoma (GB) and non-cancer from tissue samples, and we provide a real-time feedback method for endoscopic diagnostics using sound...
October 19, 2016: Analyst
Lin Teng, Xian Wang, Xiaojun Wang, Honglei Gou, Lihui Ren, Tingting Wang, Yun Wang, Yuetong Ji, Wei E Huang, Jian Xu
Rapid profiling of stress-response at single-cell resolution yet in a label-free, non-disruptive and mechanism-specific manner can lead to many new applications. We propose a single-cell-level biochemical fingerprinting approach named "ramanome", which is the collection of Single-cell Raman Spectra (SCRS) from a number of cells randomly selected from an isogenic population at a given time and condition, to rapidly and quantitatively detect and characterize stress responses of cellular population. SCRS of Escherichia coli cells are sensitive to both exposure time (eight time points) and dosage (six doses) of ethanol, with detection time as early as 5 min and discrimination rate of either factor over 80%...
October 19, 2016: Scientific Reports
Yao Tian, Kenneth S Burch
Raman spectroscopy is a powerful technique, widely used in both academia and industry. In part, the technique's extensive use stems from its ability to uniquely identify and image various material parameters: composition, strain, temperature, lattice/excitation symmetry, and magnetism in bulk, nano, solid, and organic materials. However, in nanomaterials and samples with low thermal conductivity, these measurements require long acquisition times. On the other hand, charge-coupled device (CCD) detectors used in Raman microscopes are vulnerable to cosmic rays...
October 17, 2016: Applied Spectroscopy
Dominik Kurzydłowski, Tomasz Jaroń, Andrew Ozarowski, Stephen Hill, Zvonko Jagličić, Yaroslav Filinchuk, Zoran Mazej, Wojciech Grochala
The crystal structure, magnetic properties, heat capacity, and Raman spectra of double-perovskite M2AgF4 (M = K, K3/4Rb1/4, K1/2Rb1/2, K1/4Rb3/4, and Rb) phases have been examined, adding to the body of previous results for the M = Na, Cs derivatives. The results suggest that double-perovskite K2AgF4 adopts a disordered orthorhombic Bmab structure with an antiferrodistortive arrangement of the elongated and tilted [AgF6] octahedra rather than the structure with the ferrodistortive arrangement of compressed octahedra, as suggested previously (Mazej, Z...
October 18, 2016: Inorganic Chemistry
C Weyrich, M Drögeler, J Kampmeier, M Eschbach, G Mussler, T Merzenich, T Stoica, I E Batov, J Schubert, L Plucinski, B Beschoten, C M Schneider, C Stampfer, D Grützmacher, Th Schäpers
Ternary (Bi1-x Sb x )2Te3 films with an Sb content between 0 and 100% were deposited on a Si(1 1 1) substrate by means of molecular beam epitaxy. X-ray diffraction measurements confirm single crystal growth in all cases. The Sb content is determined by x-ray photoelectron spectroscopy. Consistent values of the Sb content are obtained from Raman spectroscopy. Scanning Raman spectroscopy reveals that the (Bi1-x Sb x )2Te3 layers with an intermediate Sb content show spatial composition inhomogeneities. The observed spectra broadening in angular-resolved photoemission spectroscopy (ARPES) is also attributed to this phenomena...
October 17, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yizhi Song, Anne-Kristin Kaster, John Vollmers, Yanqing Song, Paul A Davison, Martinique Frentrup, Gail M Preston, Ian P Thompson, J Colin Murrell, Huabing Yin, C Neil Hunter, Wei E Huang
Cell sorting coupled with single-cell genomics is a powerful tool to circumvent cultivation of microorganisms and reveal microbial 'dark matter'. Single-cell Raman spectra (SCRSs) are label-free biochemical 'fingerprints' of individual cells, which can link the sorted cells to their phenotypic information and ecological functions. We employed a novel Raman-activated cell ejection (RACE) approach to sort single bacterial cells from a water sample in the Red Sea based on SCRS. Carotenoids are highly diverse pigments and play an important role in phototrophic bacteria, giving strong and distinctive Raman spectra...
October 17, 2016: Microbial Biotechnology
Dwaipayan Dutta Gupta, Dandamudi Usharani, Shyamalava Mazumdar
Three stable copper complexes of peptides derived from the copper ion binding loop of the subunit II of cytochrome c oxidase have been prepared and characterized by various spectroscopic techniques. These stable copper complexes of peptides were found to exhibit cysteine, histidine and/or methionine ligation, which has predominant σ-contribution in the Cys-Cu charge transfer. The copper(ii) peptide complexes showed type-2 EPR spectra, which is uncommon in copper-cysteinate complexes. UV-visible spectra, Raman and EPR results support a tetragonal structure of the coordination geometry around the copper ion...
October 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Joshua D Weatherston, Nolan C Worstell, Hung-Jen Wu
Surface-enhanced Raman spectroscopy (SERS) is a powerful tool with high potential for multiplexed detection of dilute analytes. However, quantitative SERS of kinetic assays can be difficult due to the variation in enhancement factors caused by changing reaction conditions. We report a method for quantitative SERS kinetic analysis using colloidal Ag-Au core-shell nanocubes (Ag@AuNCs) as the SERS substrate. This substrate is mass producible, possesses large SERS enhancement, and is resistant to degradation in most environments...
October 17, 2016: Analyst
Lei Zhou, Jing Liu, Faqin Dong
Mackinawite (FeS), widespread in low temperature aquatic environments, is generally considered to be the first Fe sulfide formed in sedimentary environments which has shown effective immobilization of heavy metals and toxic oxyanions through various sorption reactions. The spectroscopic study researches on mackinawite formed by FRB and SRB and its environmental implication for in-situ remediation of acid mine drainage where contains large amounts of Fe(3+) and SO4(2-). The XRD result of biologically synthetic particles shows that these particles are mainly composed of mackinawite (FeS0...
September 29, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jianli Zou, Christopher Sole, Nicholas E Drewett, Matej Velicky, Laurence J Hardwick
An in situ Raman spectroelectrochemical study of Li intercalation into graphite flakes with different thicknesses ranging from 1.7 nm (3 graphene layers) to 61 nm (ca. 178 layers) is presented. The lithiation behavior of these flakes was compared to commercial microcrystalline graphite with a typical flake thickness of ca. 100 nm. Li intercalation into the graphitic flakes was observed under potential control via in situ optical microscopy and Raman spectroscopy. As graphite flakes decreased in thickness, a Raman response indicative of increased tensile strain along the graphene sheet was observed during the early stages of intercalation...
October 14, 2016: Journal of Physical Chemistry Letters
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