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Raman crystallinity

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https://www.readbyqxmd.com/read/28819192/scalable-fabrication-of-the-graphitic-substrates-for-graphene-enhanced-raman-spectroscopy
#1
Tommi Kaplas, Antti Matikainen, Tarmo Nuutinen, Sari Suvanto, Pasi Vahimaa, Yuri Svirko
We propose direct synthesis of ultra-thin graphitic films on a dielectric substrate using sacrificial Ni catalyst layer, which significantly increases the crystallinity of the photoresist pyrolyzed at the temperature of 800 °C and above. A considerable amount of multilayer graphene in the photoresist film pyrolyzed in the presence of the Ni catalyst gives rise to an enhancement of the Raman signal of dye Sudan III molecules deposited on the substrate. We demonstrate comparable enhancement of the Raman signal from Sudan III molecules deposited on the fabricated graphitic substrate and those deposited on graphene, which was conventionally transferred to the silica substrate...
August 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28802174/synthesis-and-characterization-of-mno2-nio-nanocomposites-for-photocatalysis-of-tetracycline-antibiotic-and-modification-with-guanidine-for-carriers-of-caffeic-acid-phenethyl-ester-an-anticancer-drug
#2
Vinod Kumar Gupta, Ali Fakhri, Shilpi Agarwal, Elham Ahmadi, Pedram Afshar Nejad
In the present studies, modified NiO nanoparticles and MnO2/NiO nanocomposites with guanidine were synthesized by anchoring method for carriers of anticancer drug "Caffeic acid phenethyl ester". The prepared nanocomposites were characterized by using Scanning Electron Microscopy, Raman and Fourier transform infrared spectroscopy, X-ray diffraction, Vibrating sample magnetometer. The results from XRD indicated that the crystalline size of NiO nanoparticles and MnO2/NiO nanocomposites are 12 and 15nm, respectively...
August 6, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28802161/physicochemical-analysis-of-permian-coprolites-from-brazil
#3
M I C Rodrigues, J H da Silva, F Eroni P Santos, P Dentzien-Dias, J C Cisneros, A S de Menezes, P T C Freire, B C Viana
In this paper we performed the study of two coprolites (fossilized feces) collected from the exposed levels of the Pedra de Fogo Formation, Parnaiba Sedimentary Basin, and Rio do Rasto Formation, Paraná Sedimentary Basin, both of the Palaeozoic era (Permian age). They were characterized using X-ray diffractometry, infrared, Raman and energy dispersive spectroscopy techniques in order to aid our understanding of the processes of fossilization and to discuss issues related to the feeding habits of the animals which generated those coprolites, probably cartilaginous fishes...
August 8, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28800198/identification-of-crystalline-orientation-of-black-phosphorus-by-optothermal-raman-spectroscopy
#4
Xinwei Wang, Tianyu Wang, Jing Liu, Biao Xu, Ridong Wang, Pengyu Yuan, Meng Han, Shen Xu, Yangsu Xie, Yue Wu
Current polarized Raman-based techniques for identifying the crystalline orientation of black phosphorus suffer big uncertainty and unreliability because of the complex interference involving excitation laser wavelength, scattering light wavelength, and sample thickness. Here, for the first time, we present a new optothermal Raman spectroscopy (OT-Raman) for identifying crystalline orientation. With a physical mechanism based on the anisotropic optical absorption of polarized laser and the resulting heating, the OT-Raman can identify the crystalline orientation explicitly regardless of excitation wavelength and sample thickness by Raman frequency-power differential Φ (=∂ω/∂P)...
August 11, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28799608/understanding-the-graphitization-and-growth-of-free-standing-nanocrystalline-graphene-using-in-situ-transmission-electron-microscopy
#5
C N Shyam Kumar, Venkata Sai Kiran Chakravadhanula, Adnan Riaz, Simone Dehm, Di Wang, Xiaoke Mu, Benjamin Flavel, Ralph Krupke, Christian Kübel
Graphitization of polymers is an effective way to synthesize nanocrystalline graphene on different substrates with tunable shape, thickness and properties. The catalyst free synthesis results in crystallite sizes on the order of a few nanometers, significantly smaller than commonly prepared polycrystalline graphene. Even though this method provides the flexibility of graphitizing polymer films on different substrates, substrate free graphitization of freestanding polymer layers has not been studied yet. We report for the first time the thermally induced graphitization and domain growth of free-standing nanocrystalline graphene thin films using in situ TEM techniques...
August 11, 2017: Nanoscale
https://www.readbyqxmd.com/read/28792211/porous-two-dimensional-monolayer-metal-organic-framework-material-and-its-use-for-the-size-selective-separation-of-nanoparticles
#6
Yi Jiang, Gyeong Hee Ryu, Se Hun Joo, Xiong Chen, Sun Hwa Lee, Xianjue Chen, Ming Huang, Xiaozhong Wu, Da Luo, Yuan Huang, Jeong Hyeon Lee, Bin Wang, Xu Zhang, Sang Kyu Kwak, Zonghoon Lee, Rodney S Ruoff
Rational bottom-up construction of two-dimensional (2D) covalent or noncovalent organic materials with precise structural control at the atomic or molecular level remains a challenge. The design and synthesis of metal-organic frameworks (MOFs) based on new building blocks is of great significance in achieving new types of 2D monolayer MOF films. Here, we demonstrate that a complexation between copper(II) ions and tri(β-diketone) ligands yields a novel 2D MOF structure, either in the form of a powder or as a monolayer film...
August 9, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28780338/facile-functionalization-of-cotton-with-nanostructured-silver-titania-for-visible-light-plasmonic-photocatalysis
#7
Marwa Abid, Soraa Bouattour, Ana M Ferraria, David S Conceição, Ana P Carapeto, Luís F Vieira Ferreira, Ana M Botelho do Rego, Mohamed M Chehimi, Manuel Rei Vilar, Sami Boufi
In the present work, a simple, reliable and cost-effective approach to functionalize cotton fabrics with Ag-TiO2 nanoparticles strongly bound to the fibres and with visible-light-responsive photo-activity is presented. The hybrid cotton-Ag-TiO2 fabrics were characterized by Raman, AFM, FE-SEM, TGA, XPS GSDR, and LIL to confirm the generation of metallic Ag nanoparticles and crystalline TiO2 and investigate how the concentration of Ag and TiO2 precursors affected the morphology and the luminescence properties of the nanostructured layer grafted on the cotton fibres...
July 29, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28776975/dual-functional-ta-doped-electrospun-tio2-nanofibers-with-enhanced-photocatalysis-and-sers-detection-for-organic-compounds
#8
Narendra Singh, Jai Prakash, Mrinmoy Misra, Ashutosh Sharma, Raju Kumar Gupta
There is a growing interest in multifunctional nanomaterials for the detection as well as degradation of organic contaminants in the water. In this work, we report on the development of dual functional TiO2 nanofibers (TNF) with different tantalum (Ta) doping (1-10 mol %) by a simple electrospinning technique. As-prepared TNF show mesoporous dominant structure, which are favorable for photocatalytic activity due to the presence of catalytic spots. Ta doping decreases the crystalline size within TiO2 matrix because of the incorporation of Ta(5+) ions and restricts the phase transformation from anatase to rutile...
August 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28774854/analysis-of-the-dehydration-process-of-caffeine-using-backscattering-and-transmission-raman-spectroscopy
#9
Rina Takeshima, Yusuke Hattori, Satoshi Managaki, Makoto Otsuka
In the present study, the dehydration process of caffeine hydrate (CAH) was investigated by calibrating the moisture content in the caffeine tablet using backscattering Raman spectroscopy (BRS) and transmission Raman spectroscopy (TRS). The detectable depth of BRS is limited by its shallow laser penetration, while TRS is a powerful tool to determine the content of active pharmaceutical ingredients in a tablet. Our results suggest that the accuracy of a TRS-based calibration model falls beyond that of a BRS-based model...
July 31, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28773976/tribological-performance-of-green-lubricant-enhanced-by-sulfidation-if-mos%C3%A2
#10
Shih-Chen Shi
Biopolymers reinforced with nanoparticle (NP) additives are widely used in tribological applications. In this study, the effect of NP additives on the tribological properties of a green lubricant hydroxypropyl methylcellulose (HPMC) composite was investigated. The IF-MoS₂ NPs were prepared using the newly developed gas phase sulfidation method to form a multilayered, polyhedral structure. The number of layers and crystallinity of IF-MoS₂ increased with sulfidation time and temperature. The dispersity of NPs in the HPMC was investigated using Raman and EDS mapping and showed great uniformity...
October 21, 2016: Materials
https://www.readbyqxmd.com/read/28773837/one-step-synthesis-of-single-wall-carbon-nanotube-zns-core-shell-nanocables
#11
Yanli Zhang, Xiangming He, Li Wang, Jian Gao, Jianjun Li
Nanocables with a single-wall carbon nanotube (SWCNT) core and a ZnS shell were directly synthesized in one step through a thermal reaction method by using carbon, Zn, and FeS powder as starting materials. The as-fabricated nanocables were studied using scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The nanocables have diameters of ~50 nm, lengths of several micrometers, and shell thickness of ~20 nm. TEM analysis revealed that the shell is polycrystalline wurtzite-type ZnS with good crystallinity, and the core of the nanocables is one to several SWCNTs...
August 24, 2016: Materials
https://www.readbyqxmd.com/read/28773172/ion-beam-induced-atomic-mixing-in-ge-si-and-sige-studied-by-means-of-isotope-multilayer-structures
#12
Manuel Radek, Bartosz Liedke, Bernd Schmidt, Matthias Voelskow, Lothar Bischoff, John Lundsgaard Hansen, Arne Nylandsted Larsen, Dominique Bougeard, Roman Böttger, Slawomir Prucnal, Matthias Posselt, Hartmut Bracht
Crystalline and preamorphized isotope multilayers are utilized to investigate the dependence of ion beam mixing in silicon (Si), germanium (Ge), and silicon germanium (SiGe) on the atomic structure of the sample, temperature, ion flux, and electrical doping by the implanted ions. The magnitude of mixing is determined by secondary ion mass spectrometry. Rutherford backscattering spectrometry in channeling geometry, Raman spectroscopy, and transmission electron microscopy provide information about the structural state after ion irradiation...
July 17, 2017: Materials
https://www.readbyqxmd.com/read/28772669/in-situ-studies-of-structure-transformation-and-al-coordination-of-kal-moo%C3%A2-%C3%A2-during-heating-by-high-temperature-raman-and-27-al-nmr-spectroscopies
#13
Min Wang, Jinglin You, Alexander Sobol, Liming Lu, Jian Wang, Yingfang Xie
Recent interest in optimizing composition and synthesis conditions of functional crystals, and the further exploration of new possible candidates for tunable solid-state lasers, has led to significant research on compounds in this family M(I)M(III)(M(VI)O₄)₂ (M(I) = alkali metal, M(III) = Al, In, Sc, Fe, Bi, lanthanide; M(VI) = Mo, W). The vibrational modes, structure transformation, and Al coordination of crystalline, glassy, and molten states of KAl(MoO₄)₂ have been investigated by in-situ high temperature Raman scattering and (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, together with first principles density functional simulation of room temperature Raman spectrum...
March 17, 2017: Materials
https://www.readbyqxmd.com/read/28764360/from-isolated-diamondoids-to-a-van-der-waals-crystal-a-theoretical-and-experimental-analysis-of-a-trishomocubane-and-a-diamantane-dimer-in-the-gas-and-solid-phase
#14
Christoph Tyborski, Reinhard Meinke, Roland Gillen, Tobias Bischoff, Andre Knecht, Robert Richter, Andrea Merli, Andrey A Fokin, Tetyana V Koso, Vladimir N Rodionov, Peter R Schreiner, Thomas Möller, Torbjörn Rander, Christian Thomsen, Janina Maultzsch
The electronic properties of sp(2)/sp(3) diamondoids in the crystalline state and in the gas phase are presented. Apparent differences in electronic properties experimentally observed by resonance Raman spectroscopy in the crystalline/gas phase and absorption measurements in the gas phase were investigated by density functional theory computations. Due to a reorganization of the molecular orbitals in the crystalline phase, the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy gaps are lowered significantly by 0...
July 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28752956/black-phosphorus-optical-characterization-properties-and-applications
#15
REVIEW
Shengxi Huang, Xi Ling
The rise of black phosphorus (BP) as a new family member of two-dimensional (2D) materials brings new concepts and applications to the field, because of the infrared band gap and anisotropic properties of such materials. Among many excellent properties of BP, the optical property attracts special attention in recent years. Optical methods have been widely and successfully used in characterizing BP, not only to obtain the structural information (such as thickness and crystalline orientation), but also to probe the fundamental properties of BP in terms of the behavior of electrons, phonons, excitons etc...
July 28, 2017: Small
https://www.readbyqxmd.com/read/28751072/the-interrelationship-of-microstructure-and-hardness-of-human-coronal-dentin-using-reference-point-indentation-technique-and-micro-raman-spectroscopy
#16
Rasoul Seyedmahmoud, Jacob D McGuire, Yong Wang, Ganesh Thiagarajan, Mary P Walker
OBJECTIVES: The aim of this paper is to determine the interrelationship between the microstructure - in terms of chemical composition and crystallinity - to the microhardness of coronal dentin. METHODS: Dentin microhardness was tested by a novel reference point indenter and compared to the traditional Knoop hardness method. Micro-Raman spectroscopy was used to determine the chemical composition and crystallinity of dentin. RESULTS: From the occlusal groove to the border of the coronal pulp chamber, dentin hardness decreased from superficial dentin (SD) to deep dentin (DD)...
July 24, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28746834/development-of-an-analytical-method-for-crystalline-content-determination-in-amorphous-solid-dispersions-produced-by-hot-melt-extrusion-using-transmission-raman-spectroscopy-a-feasibility-study
#17
L Netchacovitch, E Dumont, J Cailletaud, J Thiry, C De Bleye, P-Y Sacré, M Boiret, B Evrard, Ph Hubert, E Ziemons
The development of a quantitative method determining the crystalline percentage in an amorphous solid dispersion is of great interest in the pharmaceutical field. Indeed, the crystalline Active Pharmaceutical Ingredient transformation into its amorphous state is increasingly used as it enhances the solubility and bioavailability of Biopharmaceutical Classification System class II drugs. One way to produce amorphous solid dispersions is the Hot-Melt Extrusion (HME) process. This study reported the development and the comparison of the analytical performances of two techniques, based on backscattering and transmission Raman spectroscopy, determining the crystalline remaining content in amorphous solid dispersions produced by HME...
July 23, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28735188/photoelectrochemical-pec-studies-on-cu2sns3-cts-thin-films-deposited-by-chemical-bath-deposition-method
#18
H D Shelke, A C Lokhande, J H Kim, C D Lokhande
Cu2SnS3 (CTS) thin films have been successfully deposited on a cost-effective stainless steel substrate by simple and inexpensive chemical bath deposition (CBD) method. The films are deliberated in provisos of their structural, morphological, optical and photoelectrochemical (PEC) properties before and after annealing treatment, using various physico-chemical techniques. The XRD studies showed the formation of triclinic phase of CTS films with nanocrystalline structure. Also, the crystallinity is enhanced with annealing and the secondary phase of Cu2S observed...
July 11, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28732164/electrochemical-intercalation-of-mg-2-into-anhydrous-and-hydrated-crystalline-tungsten-oxides
#19
Ruocun Wang, Ching-Chang Chung, Yang Liu, Jacob L Jones, Veronica Augustyn
The reversible intercalation of multivalent cations, especially Mg(2+), into a solid-state electrode is an attractive mechanism for next-generation energy storage devices. These reactions typically exhibit poor kinetics due to a high activation energy for interfacial charge-transfer and slow solid-state diffusion. Interlayer water in V2O5 and MnO2 has been shown to improve Mg(2+) intercalation kinetics in nonaqueous electrolytes. Here, the effect of structural water on Mg(2+) intercalation in nonaqueous electrolytes is examined in crystalline WO3 and the related hydrated and layered WO3·nH2O (n = 1, 2)...
July 27, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28731340/chemistry-of-sputter-deposited-lithium-sulfide-films
#20
Michael J Klein, Gabriel M Veith, Arumugam Manthiram
Lithium sulfide (Li2S) is under intense study because it is the insulating discharge product of ultrahigh energy density lithium-sulfur (Li-S) batteries and a candidate cathode material for lithium-metal-free Li-S cells. In this work, we report the fabrication of an apparatus for sputter deposition of Li2S films ranging in thickness from a few nanometers to several micrometers at rates over 2 nm min(-1). High-temperature annealing of the films is shown to produce crystalline films of high chemical purity Li2S for the first time...
July 27, 2017: Journal of the American Chemical Society
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