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Raman spectra

Zhen Zhou, Jin Luo, Wei Sun, Jing-Feng Li
Extensive studies on (Bi0.5Na0.5)TiO3-BaTiO3 piezoceramics have aroused growing interest in developing high-performance piezoelectric films based on this promising lead-free piezoelectric system. High quality (1 - x%) (Bi0.5Na0.5)TiO3-x% BaTiO3 (x = 0-15) thin films were synthesized on Pt(111)/Ti/SiO2/Si(100) substrates via a sol-gel method. The phase transitions as functions of composition and temperature were investigated by X-ray diffraction (XRD) and temperature-dependent Raman spectra analysis. A morphotropic phase boundary (MPB) located at 5 ≤ x ≤ 10 was found in the films, being identical to that in bulk materials...
July 19, 2017: Physical Chemistry Chemical Physics: PCCP
Hai-Ru Li, Xin-Xin Tian, Xue-Mei Luo, Miao Yan, Yue-Wen Mu, Hai-Gang Lu, Si-Dian Li
With inspirations from recent discoveries of the cage-like borospherene B40 and perfectly planar Co ∈ B18(-) and based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of the novel planar Ni ∈ B18 (1), cage-like heteroborospherenes Nin ∈ B40 (n = 1-4) (2-5), and planar heteroborophenes Ni2 ∈ B14 (6, 7) which all contain planar or quasi-planar heptacoordinate transition-metal (phTM) centers in η(7)-B7 heptagons. The nearly degenerate Ni2 ∈ B14 (6) and Ni2 ∈ B14 (7) monolayers are predicted to be metallic in nature, with Ni2 ∈ B14 (6) composed of interwoven boron double chains with two phNi centers per unit cell being the precursor of cage-like Nin ∈ B40 (n = 1-4) (2-5)...
July 18, 2017: Scientific Reports
Hao Ding, Andrew W Dupont, Shashideep Singhal, Larry D Scott, Sushovan Guha, Mamoun Younes, Xiaohong Bi
The goal of this study is to evaluate endoscopic Raman spectroscopy as a noninvasive technique to determine histological inflammatory status of colitis. Colon mucosal composition was investigated in vivo from patients with ulcerative colitis (UC) and from age- and body mass index (BMI) matched controls using endoscope-coupled Raman spectroscopy. The results were co-registered with histological assessment of inflammatory status at the same locations. Substantial decreases (50-60%) in the content of phosphotidylcholines (PCs) and total lipids were observed in inflamed colon tissue (histology grade 1, 2 and 3) compared to those from the quiescent (histology grade 0) and from the controls...
July 1, 2017: Biomedical Optics Express
Tingting You, Xiufeng Lang, Anping Huang, Penggang Yin
A computational study on aromatic dithiol derivatives (HS-Ar-X-Ar-SH, X=O, S, Se, NH, CH2, NN, CHCH, CC) interacting with gold cluster(s) was presented to investigate the chemical enhancement mechanism related to surface-enhanced Raman spectroscopy (SERS) for molecular junctions. Density functional theory (DFT) were performed on derivatives molecules as well as their single-end-linked (SEL) or double-end-linked (DEL) complexes for geometric, spectra, electronic and excitation properties, leading to discussions on dominant factor during SERS process...
July 12, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Lin Wang, Tatsuya Ishiyama, Akihiro Morita
A flexible and polarizable molecular model of ethanol is developed to extend our investigation of thermodynamic, structural and vibrational properties of liquid and interface. Molecular dynamics (MD) simulation with the present model confirmed that this model well reproduces a number of properties of liquid ethanol, including density, heat of vaporization, surface tension, molecular dipole moment, and trans/gauche ratio. In particular, the present model can describe vibrational IR, Raman and sum frequency generation (SFG) spectra of ethanol and partially deuterated analogues with reliable accuracy...
July 17, 2017: Journal of Physical Chemistry. A
Tzu-Chiao Wei, Hsin-Ping Wang, Ting-You Li, Chun-Ho Lin, Ying-Hui Hsieh, Ying-Hao Chu, Jr-Hau He
Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction)...
July 17, 2017: Advanced Materials
Lei Yang, Alolika Mukhopadhyay, Yucong Jiao, Qiang Yong, Liao Chen, Yingjie Xing, Jonathan Hamel, Hongli Zhu
Thermally insulating materials, made from earth-abundant and sustainable resources, are highly desirable in the sustainable construction of energy efficient buildings. Cellulose from wood has long been recognized for these characteristics. However, cellulose can be a flammability hazard, and for construction this has been addressed via chemical treatment such as that with halogen and/or phosphorus, which leads to further environmental concerns. Fortunately, the structure of cellulose lends itself well to chemical modification, giving great potential to explore interaction with other compounds...
July 17, 2017: Nanoscale
Sefa Celik, Serda Kecel-Gunduz, Sevim Akyuz, Aysen E Ozel
The theoretically possible stable conformer of the cyclic heptapeptide, that has significant anti-metastatic activity, was examined by conformational analysis followed by DFT calculations. Experimental infrared and Raman spectroscopy, together with theoretical DFT (6-31G (d,p) basis set)-based quantum chemical calculations, have been used to understand the structural and spectral characteristics of cyclo(Gly-Arg-Gly-Asp-Ser-Pro-Ala) {cyclo(GRGDSPA)}. A complete analysis of the vibrational spectrum has been reported on the basis of potential energy distribution (PED %) data of the vibrational modes...
July 17, 2017: Journal of Biomolecular Structure & Dynamics
Jaganathan Senthilnathan, Masahiro Yoshimura
The present works demonstrate the formation of reduced graphene oxide (r-GO) and aminopyridine (r-GO-(AmPy)n) hybrid by submerged liquid plasma process. Raman spectra shows the ID/IG ratio of GO, r-GO and r-GO-(AmPy)n are 2.2, 1.91 and 2.0, respectively. The decrease in ID/IG ratio of r-GO clearly indicate the reduction of oxygen functional groups and restoration of sp(2) network in r-GO domain. The pyridinic and pyrrolic functional group present in rGO-(AmPy)n hybrids shows a distinct redox peaks in cyclic voltameter at the scan rates of 5, 10 and 25mV/s...
June 28, 2017: Journal of Hazardous Materials
Bence Kozma, Edit Hirsch, Szilveszter Gergely, László Párta, Hajnalka Pataki, András Salgó
In this study, near-infrared (NIR) and Raman spectroscopy were compared in parallel to predict the glucose concentration of Chinese hamster ovary cell cultivations. A shake flask model system was used to quickly generate spectra similar to bioreactor cultivations therefore accelerating the development of a working model prior to actual cultivations. Automated variable selection and several pre-processing methods were tested iteratively during model development using spectra from six shake flask cultivations...
July 6, 2017: Journal of Pharmaceutical and Biomedical Analysis
Marilena Ricci, Cristiana Lofrumento, Maurizio Becucci, Emilio M Castellucci
Using time-dependent density functional theory in conjunction with B3LYP functional and LANL2DZ/6-31+g(d,p) basis sets, static and pre-resonance Raman spectra of the indigo-Ag2 complex have been calculated. Structure optimization, excitation energies and pre-resonance Raman spectra of the indigo molecule have been obtained at the same level of theory. The available experimental Raman spectra at 1064, 785 and 514nm and the SERS spectra at 785 and 514nm have been well reproduced by the calculation. Experimental SERS spectra are confronted with the calculated pre-resonance Raman spectra obtained for the indigo-Ag2 complex...
July 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Alexander J Makowski, Mathilde Granke, Oscar D Ayala, Sasidhar Uppuganti, Anita Mahadevan-Jansen, Jeffry S Nyman
A decline in the inherent quality of bone tissue is a † Equal contributors contributor to the age-related increase in fracture risk. Although this is well-known, the important biochemical factors of bone quality have yet to be identified using Raman spectroscopy (RS), a nondestructive, inelastic light-scattering technique. To identify potential RS predictors of fracture risk, we applied principal component analysis (PCA) to 558 Raman spectra (370-1720 cm(-1)) of human cortical bone acquired from 62 female and male donors (nine spectra each) spanning adulthood (age range = 21-101 years)...
January 1, 2017: Applied Spectroscopy
Yanzhi Bai, Zhenhai Yu, Ran Liu, Nana Li, Shuai Yan, Ke Yang, Bingbing Liu, Dongqing Wei, Lin Wang
Static pressure is an alternative method to chemical pressure for tuning the crystal structure, bonds, and physical properties of materials, and is a significant technique for the synthesis of novel materials and fundamental research. In this letter, we report the crystallization and phase transformation of p-xylene under high pressure. Our optical micrographic observations and the appearance of lattice modes in the Raman and infrared (IR) spectra indicated that p-xylene crystallizes at ∼0.1 GPa. The X-ray diffraction (XRD) pattern at 0...
July 13, 2017: Scientific Reports
Qiang Cao, Jiajun Zhang, Jian Du, Hongming Zhao, Sheng Liu, Qing Peng
Ion implantation is widely used to fabricate advanced optical and optoelectronic materials and devices. However, nanoscale defects generated during the ion implantation process severely affect the quality and properties of the material and device. Here, combining computational simulations and experiments, we investigate the mechanism for defect repair in fused silica after Cu ion implantation using femtosecond laser irradiation with an energy fluence much lower than the ablation threshold. Atomic force microscopy demonstrates no unexpected ablation...
July 12, 2017: Nanoscale
Wei Huang, Shujiang Ding, Yong Chen, Wanjun Hao, Xiaoyong Lai, Juan Peng, Jinchun Tu, Yang Cao, Xiaotian Li
The 3D NiO hollow sphere/reduced graphene oxide (rGO) composite was synthesized according to the coordinating etching and precipitating process by using Cu2O nanosphere/graphene oxide (GO) composite as template. The morphology, structure, and composition of the materials were characterized by SEM, TEM, HRTEM, XPS, and Raman spectra, and the electrochemical properties were studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. Moreover, the electrochemical activity of the composite materials with different morphologies were also investigated, which indicating a better combination of the NiO hollow sphere and the rGO...
July 12, 2017: Scientific Reports
Prasad L Polavarapu, Cody L Covington, Vijay Raghavan
A chemical structure (CS) identifies the connectivities between atoms, and the nature of those connections, for a given elemental composition. For chiral molecules, in addition to the identification of CS, the identification of the correct absolute configuration (AC) is also needed. Several chiral natural products are known whose CSs were initially mis-identified and later corrected, and these errors were often discovered during the total synthesis of natural products. In this work, we present a new and convenient approach that can be used with Raman optical activity (ROA) and vibrational circular dichroism (VCD) spectroscopies, to distinguish between the correct and incorrect CSs of chiral compounds...
July 12, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Jie Wei, Chunfang Wu, Yalong Liu, Yaxin Guo, Tiantian Yang, Dawei Wang, Zhuo Xu, Raphael Haumont
Rare-earth ions (RE = La(3+), Nd(3+), and Er(3+)) substituted BiFeO3 (BFO) ceramics were synthesized by a conventional solid-state sintering procedure. X-ray diffraction patterns and Raman spectra confirm a rhombohedral R3c symmetry in all samples with significant distortion in FeO6 octahedron, as well as the occurrence of remarkable spin-phonon coupling and notable change in magnetic transition temperature induced by RE dopants. The enhanced magnetization was observed in all RE-doped BFO ceramics, unveiling that the spatial spin structure of BFO should be perturbed by RE dopants...
July 12, 2017: Inorganic Chemistry
Katelyn M Dreux, Louis E McNamara, John T Kelly, Ashley M Wright, Nathan I Hammer, Gregory S Tschumper
Although ammonia borane is isoelectronic with ethane and they have similar structures, BH3NH3 exhibits rather atypical bonding compared to that in CH3CH3. The central bond in ammonia borane is actually a coordinate covalent or dative bond rather than the conventional covalent C-C bond in ethane where each atom donates one electron. In addition, strong intermolecular dihydrogen bonds can form between two or more ammonia borane molecules compared to the relatively weak dispersion forces between ethane molecules...
July 11, 2017: Journal of Physical Chemistry. A
Mircea Comanescu, Cyril Muehlethaler, John Lombardi, Marco Leona, Thomas A Kubic
No abstract text is available yet for this article.
January 1, 2017: Applied Spectroscopy
Tomotsumi Fujisawa, Ryan L Leverenz, Momoka Nagamine, Cheryl A Kerfeld, Masashi Unno
The orange carotenoid protein (OCP) plays an important role in photoprotection in cyanobacteria, which is achieved by the photoconversion from the orange dark state (OCPO) to the red active state (OCPR). Using Raman optical activity (ROA), we studied the conformations of the carotenoid chromophore in the active sites of OCPO and OCPR. This ROA measurement directly observed the chromophore conformation of native OCP in solution, and the measurement of OCPR first demonstrated the ROA spectroscopy for the transient species...
July 10, 2017: Journal of the American Chemical Society
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