Papers by Keyword: Raman Spectroscopy

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Authors: Wolfgang Düngen, Reinhart Job, Yue Ma, Yue Long Huang, Wolfgang R. Fahrner, L.O. Keller, J.T. Horstmann
Abstract: µ-Raman measurements were carried out on hydrogen implanted, plasma hydrogenated and subsequently annealed Cz Silicon samples, respectively. In comparison to as-implanted or asplasma treated samples, in consideration of the thermal evolution, the effects of the implanted and subsequently plasma treated samples were analyzed. An enhanced trapping of molecular hydrogen in multivacancies has been observed after hydrogen implantation and subsequent plasma hydrogenation. In comparison to as-implanted samples, the intensity of the local vibrational modes (LVM) of vacancy-hydrogen complexes and silicon-hydrogen bonds are increasing.
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Authors: Larry L. Hench, Ioan Notingher
Abstract: We present a new bio-photonic method based on Raman spectroscopy able to characterize living cells in in-vitro cultures. The main advantages of this technology are: no labels or other contrast enhancers are required; provides real-time analysis; cells can be maintained in physiological conditions during the measurements; no cell-damage is induced during the measurements; it is rich in information about the biochemical composition of the cell. The results show that this spectroscopic method can be used to study the most important cellular functions involved in cell-biomaterial interactions, such as cell death, differentiation, de-differentiation and mineralization. The method offers the potential for studying cell-bioceramics interaction and reduce the need of animal testing until the final steps of proving efficacy prior to clinical trials.
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Authors: Joydip Sengupta, Sovan Kumar Panda, Chacko Jacob
Abstract: The effect of Fe and Ni catalysts on the synthesis of carbon nanotubes (CNTs) using atmospheric pressure chemical vapor deposition (APCVD) was investigated. Distribution of the catalyst particles over the Si substrate was analyzed by atomic force microscopy (AFM). Characterization by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopic measurements over the grown species is reported. The study clearly shows that the catalyst strongly influences morphology and microstructure of the grown CNTs.
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Authors: J.H. Edgar, L.H. Robins, S.E. Coatney, L. Liu, J. Chaudhuri, K. Ignatiev, Z. Rek
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Authors: S. Nakhodchi, Gabrielle Hilson, David John Smith, Peter E.J. Flewitt
Abstract: In this paper the challenges associated with the determination of within section macrostresses in the non-metallic materials porous reactor core graphites, glasses and thermally grown oxides, will be considered, with respect to the length-scale over which such measurements are required. Examples are briefly presented to demonstrate the capability of the methods selected, which include deep hole drilling and photoluminescence and Raman spectroscopy. These techniques span the length-scale from micro-metres to tens of millimetres. The measured values will be discussed with respect to the confidence with which these techniques may be applied and hence benefits for life/integrity evaluation.
221
Authors: M.S. Shamsudin, S.M. Sanip
Abstract: The unsurpassed and exceptional properties of graphene (Gr) have prompted significant progress toward Gr-based applications, and have furthermore unleashed a host of complimentary two-dimensional materials that provide new, and emerging technologies synergistic with an already well-established Gr science. The Raman spectroscopy reveals both basic and advance features. It emerged as an important optical and structural characterization tool, following in the footsteps of related form of carbon. Till date, no comprehensive descriptions of Raman spectroscopy on Gr characterization have been published yet. This is to say that, no review can possibly complete. We have presented an extensive overview of the Raman spectroscopy, filled-up this gap and discussed the theoretical background associated with the Gr and other carbon-based materials, and some thoughts about the future of this field are highlighted. Thus, it would be used as a reference guide for the utilization of Raman spectroscopy to investigate the various features of Gr and carbon-based materials.
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Authors: Mohd Zulfadli Adenan, Mansor Ahmad, Noramaliza Mohd Noor, Elias Saion
Abstract: Polymer gel is a kind of radiation dosimetry system that has been applied widely in radiotherapy treatment. In this study, the samples of NIPAM-based polymer gel which posses a good potential as 3D radiation dosimetry are synthesized. The samples of polymer gel were irradiated up to 20 Gy by using gamma cell instrument with 60Co sources at a constant dose rate. Upon irradiation, then the chemical changes in polymer gel were characterized by using Raman spectroscopy. The polymerization was referred to an increment in Raman intensity at 815 cm-1, assigned for C-C stretching mode of NIPAM polymer gel, as the dose increased. The consumptions of the co-monomers were referred to a decrement in Raman intensities at 1025 cm-1 and 2353 cm-1 assigned for C=C stretching modes of NIPAM and BIS respectively, as the dose increased. Result shows that the amount of carbon single bonds increases while the amount of carbon covalent bonds decreases following irradiation.
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Authors: Wei Wen Liu, Tijjani Adam, Azizan Aziz, Siang Piao Chai, Abdul Rahman Mohamed, U. Hashim
Abstract: The effect of calcination temperature for Fe2O3/MgO catalysts on the formation of carbon nanotubes (CNTs) was examined. CNTs were synthesized over Fe2O3/MgO catalysts calcined at different temperatures by catalytic decomposition of methane at 1000°C. The synthesized CNTs were investigated by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results show that the effect of calcination temperatures greatly governed the diameter and the quality of the SWCNTs formed. The catalysts calcined at 500, 600 and 700°C produced CNTswith the diameters of 1.53, 1.95 and 2.97nm, respectively. Generally, an increase in the calcination temperature increases the average diameter and decreases the quality of the CNTs produced.
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Authors: Masanobu Yoshikawa
Abstract: The Raman spectra of boron-doped single-crystalline diamond were measured at excitation wavelengths between 364.0 and 1064.0 nm and found that the first-order Raman band at 1332 cm-1 shifts to the low-frequency side, broadens, and develops a derivative-like lineshape as the boron concentration increases. The derivative-like lineshape can be explained by Fano interference. Furthermore, I found that the asymmetric lineshape changes between excitation wavelengths of 514.5 and 785.0 nm. From a comparison of the normalized relative Raman intensity as a function of the excitation energy and the density of states (DOS) in the valence band in the B-doped diamond calculated previously by the coherent potential approximation, the abnormal change in the Raman lineshape is attributed to a change in the DOS in the valence band at approximately 2.0 eV. Raman spectroscopy provides us with extensive information on carrier concentrations, and electronic band structures of B-doped diamond.
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Authors: Yuan Zhu Mi, Yue Luo
Abstract: Actinozoan-like carbon materials with high yields have been successfully synthesized via a solvothermal route in a stainless steel autoclave. In this process, polyethylene glycol, magnesium acetate and n-butanol were used as starting materials. The resulting products were characterized with X-ray powder diffractometer (XRD), energy-dispersive X-ray spectra (EDX), Raman spectroscopy and scanning electron microscopy (SEM). The actinozoan-like carbon materials have diameters ranging from 100 nm to 120 nm, and lengths ranging from several microns to dozens of microns. The optimal reaction conditions to obtain actinozoan-like carbon materials are 500 °C and 12h.
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