scholarly journals Raman Spectroscopy and Mapping Analysis of Low-Dimensional Nanostructured Materials and Systems

2021 ◽  
Author(s):  
Karthikeyan Krishnamoorthy ◽  
Sang-Jae Kim
Keyword(s):  
Raman Spectroscopy ◽  
Stoichiometric Composition ◽  
Electrical Energy ◽  
Composition And Structure ◽  
Nanostructured Polymer ◽  
Mapping Analysis ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Raman Spectral

This chapter describes the use of Raman spectroscopy and mapping analysis for the characterization of low dimensional nanostructures, including 2D sheets (graphene oxide, graphene sheets, MoS2, siloxene), and one-dimensional carbyne chains. The Raman mapping analysis and their application towards understanding the molecular level interactions in these low dimensional materials, nanostructured polymer composites, and nanopaints are also discussed. The stoichiometric composition and structure of these low dimensional materials were correlated with the Raman spectral and mapping analysis. Further, Raman spectroscopy for understanding or probing the mechanism of mechanical to electrical energy harvesting properties of carbyne films via the structural transformation from cumulene to polynne networks of carbyne is demonstrated.

scholarly journals Thermal Characterization of Low-Dimensional Materials by Resistance Thermometers

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1740 ◽  
Author(s):  
Yifeng Fu ◽  
Guofeng Cui ◽  
Kjell Jeppson
Keyword(s):  
Thermal Performance ◽  
Three Dimensional ◽  
Thermal Characterization ◽  
Resistance Thermometer ◽  
Light Emitting ◽  
Resistance Thermometers ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Boron Nitride Films

The design, fabrication, and use of a hotspot-producing and temperature-sensing resistance thermometer for evaluating the thermal properties of low-dimensional materials are described in this paper. The materials that are characterized include one-dimensional (1D) carbon nanotubes, and two-dimensional (2D) graphene and boron nitride films. The excellent thermal performance of these materials shows great potential for cooling electronic devices and systems such as in three-dimensional (3D) integrated chip-stacks, power amplifiers, and light-emitting diodes. The thermometers are designed to be serpentine-shaped platinum resistors serving both as hotspots and temperature sensors. By using these thermometers, the thermal performance of the abovementioned emerging low-dimensional materials was evaluated with high accuracy.

Raman Spectral Characterization of Pure and Doped Fused Silica Optical Fibers

1975 ◽  
Vol 29 (4) ◽  
pp. 337-344 ◽  
Author(s):  
G. E. Walrafen ◽  
J. Stone
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Optical Fibers ◽  
Fused Silica ◽  
Laser Raman ◽  
Laser Raman Spectra ◽  
Raman Spectral ◽  
Oh Content ◽  
Absorption Measurements

The utility of Raman spectroscopy as a means of characterizing the properties of pure and doped fused silica has been investigated. Laser-Raman spectra were obtained by forward scattering from solid optical fibers ∼35 to 85 m in length using 514.5 nm excitation with an “image slicer” and a Cary model 81 instrument. Clad and unclad fibers of fused silica and doped fibers having SiO2-GeO2 and SiO2-GeO2-B2O3 cores were examined. Raman spectra were also obtained from bulk samples of glasses, including pure GeO2, pure B2O3, and various compositions of SiO2-GeO2, SiO2-B2O3, and SiO2-GeO2-B2O3. The addition of dopants to fused silica was found to alter the Raman spectrum both by the appearance of new bands, roughly proportional to dopant concentration and not common either to the fused silica or to the dopant alone, and by the marked alteration of other Raman bands, which is indicative of changes in the local intermolecular order. Thus, addition of GeO2 produces new Raman bands at ∼675 and ∼1000 cm−1; and of B2O3, new bands at ∼940 and ∼1350 cm−1. Addition of GeO2 and/or B2O3 weakens the relatively sharp Raman lines near 485 and 600 cm−1 (and a similar but small effect was also noted with increasing OH content). GeO2 and B2O3 together also produce observable narrowing of the broad intense 440 cm−1 Raman contour. These spectral effects are interpreted, respectively, in terms of a decrease in the concentrations of [Formula: see text] and [Formula: see text] defects produced by dopant addition and of a concomitant reordering of the silica structure. Raman spectroscopy thus appears to be a useful optical technique for elucidating the properties of dopants that have been especially chosen for good optical transmission and hence are not easily detectable by absorption measurements.

Growth and Characterization of 1D Bi2Te3 Nanowires

2005 ◽  
Vol 886 ◽  
Author(s):  
M. Craps ◽  
Nick Gothard ◽  
Rahul Rao ◽  
Jian He ◽  
JoAn Hudson ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Room Temperature ◽  
Iron Catalyst ◽  
Inert Atmosphere ◽  
Laser Vaporization ◽  
Theoretical Studies ◽  
Low Dimensional ◽  
Quartz Substrates ◽  
Low Dimensional Materials

ABSTRACTBulk bismuth telluride (Bi2Te3) is one of the best known thermoelectric materials with a figure of merit ZT ∼1 at room temperature. Theoretical studies have suggested that low-dimensional materials may exhibit ZT values that exceed 1. In this study, we used the pulsed laser vaporization (PLV) method to prepare Bi2Te3 nanowires on silicon and quartz substrates by ablating Bi2Te3 targets in an inert atmosphere. Nano-sized gold or iron catalyst particles were used to seed the growth of the Bi2Te3 nanowires. Results from electron microscopy and Raman spectroscopy are discussed.

scholarly journals Raman Characterization of Fungal DHN and DOPA Melanin Biosynthesis Pathways

2021 ◽  
Vol 7 (10) ◽  
pp. 841
Author(s):  
Benjamin D. Strycker ◽  
Zehua Han ◽  
Aysan Bahari ◽  
Tuyetnhu Pham ◽  
Xiaorong Lin ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Wild Type ◽  
Melanin Biosynthesis ◽  
Composition And Structure ◽  
Raman Spectral Data ◽  
Dopa Melanin ◽  
Inhibition Studies ◽  
Raman Spectral ◽  
Fungal Melanins

Fungal melanins represent a resource for important breakthroughs in industry and medicine, but the characterization of their composition, synthesis, and structure is not well understood. Raman spectroscopy is a powerful tool for the elucidation of molecular composition and structure. In this work, we characterize the Raman spectra of wild-type Aspergillus fumigatus and Cryptococcus neoformans and their melanin biosynthetic mutants and provide a rough “map” of the DHN (A. fumigatus) and DOPA (C. neoformans) melanin biosynthetic pathways. We compare this map to the Raman spectral data of Aspergillus nidulans wild-type and melanin biosynthetic mutants obtained from a previous study. We find that the fully polymerized A. nidulans melanin cannot be classified according to the DOPA pathway; nor can it be solely classified according to the DHN pathway, consistent with mutational analysis and chemical inhibition studies. Our approach points the way forward for an increased understanding of, and methodology for, investigating fungal melanins.

Atomistic and dynamic structural characterizations in low-dimensional materials: recent applications of in situ transmission electron microscopy

Microscopy ◽  
2019 ◽  
Author(s):  
He Zheng ◽  
Fan Cao ◽  
Ligong Zhao ◽  
Renhui Jiang ◽  
Peili Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
And Performance ◽  
Low Dimensional ◽  
Low Dimensional Materials

Abstract In situ transmission electron microscopy has achieved remarkable advances for atomic-scale dynamic analysis in low-dimensional materials and become an indispensable tool in view of linking a material’s microstructure to its properties and performance. Here, accompanied with some cutting-edge researches worldwide, we briefly review our recent progress in dynamic atomistic characterization of low-dimensional materials under external mechanical stress, thermal excitations and electrical field. The electron beam irradiation effects in metals and metal oxides are also discussed. We conclude by discussing the likely future developments in this area.

Raman studies of technetium in borosilicate waste glass

2007 ◽  
Vol 95 (5) ◽  
Author(s):  
David A. McKeown ◽  
Andrew C. Buechele ◽  
Wayne W. Lukens ◽  
D. K. Shuh ◽  
Ian L. Pegg
Keyword(s):  
Raman Spectroscopy ◽  
Waste Glass ◽  
Borosilicate Glasses ◽  
Coordination Environment ◽  
X Ray ◽  
Waste Vitrification ◽  
X Ray Absorption ◽  
Raman Spectral

The characterization of technetium (Tc) environments in borosilicate glasses is important with regard to the long-term isolation of Tc in nuclear wastes from the environment by waste vitrification. In this study, Raman spectroscopy was used to detect Tc in various borosilicate waste glass formulations in which Tc valence and average coordination environment were previously characterized by X-ray absorption spectroscopy. Raman spectral comparisons between chemically equivalent Tc-containing and Tc-free borosilicate glass pairs indicate Tc-dependent features near 320 and 910 cm

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