keyword
MENU ▼
Read by QxMD icon Read
search

Raman spectra

keyword
https://www.readbyqxmd.com/read/28241581/crystal-growth-optical-spectroscopy-and-laser-action-of-tm-sup-3-sup-doped-monoclinic-magnesium-tungstate
#1
Lizhen Zhang, Haifeng Lin, Ge Zhang, Xavier Mateos, Josep Maria Serres, Magdalena Aguiló, Francesc Díaz, Uwe Griebner, Valentin Petrov, Yicheng Wang, Pavel Loiko, Elena Vilejshikova, Konstantin Yumashev, Zhoubin Lin, Weidong Chen
We report on the crystal growth, spectroscopic investigation and laser performance of Tm<sup>3+</sup>-doped monoclinic magnesium tungstate (Tm:MgWO<sub>4</sub>), for the first time, to the best of our knowledge. A high-quality crystal has been grown by the top seeded solution growth method. The relevant spectroscopic properties are characterized in terms of absorption, luminescence and Raman spectroscopy. Judd-Ofelt (J-O) analysis is performed to evaluate the spontaneous emission probabilities and the radiative lifetimes...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28240325/origin-of-asymmetric-broadening-of-raman-peak-profiles-in-si-nanocrystals
#2
Yukun Gao, Penggang Yin
The asymmetric peak broadening towards the low-frequency side of the Raman-active mode of Si nanocrystals with the decreasing size has been extensively reported in the literatures. In this study, an atomic coordination model is developed to study the origin of the ubiquitous asymmetric peak on the optical phonon fundamental in the Raman spectra of Si nanocrystals. Our calculation results accurately replicate the line shape of the experimentally measured optical Raman curves. More importantly, it is revealed that the observed asymmetric broadening is mainly caused by the surface bond contraction and the quantum confinement...
February 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28237087/e-configuration-structures-of-epa-and-dha-derived-from-euphausia-superba-and-their-significant-inhibitive-effects-on-growth-of-human-cancer-cell-lines-in-vitro
#3
Weilong Zheng, Xudong Wang, Wenjing Cao, Bowen Yang, Ying Mu, Yuesheng Dong, Zhilong Xiu
Many bioactive components such as poly-unsaturated fatty acids (e.g. EPA and DHA), phospholipids and astaxanthin are known in Antarctic krill (Euphausia superba) oil. The krill DHA and EPA are generally considered to be similar to natural ones. However, two chemical compounds which were separated from Antarctic krill oil and identified as EPA and DHA by HRESIMS and NMR acted much more effective inhibitive activities on growth of several cell lines (U937, K562, SMMC-7721, PC-3, MDA-MB-231, HL60 and MCF-7) than those from sturgeon liver and commercial fish oil...
February 2017: Prostaglandins, Leukotrienes, and Essential Fatty Acids
https://www.readbyqxmd.com/read/28235996/rapid-urinary-tract-infection-diagnostics-by-surface-enhanced-raman-spectroscopy-sers-identification-and-antibiotic-susceptibilities
#4
W R Premasiri, Ying Chen, P M Williamson, D C Bandarage, C Pyles, L D Ziegler
SERS spectra of 12 bacterial strains of urinary tract infection (UTI) clinical isolates grown and enriched from urine are reported. A partial least squares-discriminant analysis (PLS-DA) classification treatment of these SERS spectra results in strain level identification with >95% sensitivity and >99% specificity. The classification model successfully identified the SERS spectra of a urine-cultured strain not used to build this statistical model. Enrichment was accomplished by a filtration and centrifugation protocol...
February 24, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28231482/fourier-transform-infrared-and-raman-spectroscopy-in-the-study-of-phase-transitions-in-dipyrazolium-iodide-triiodide-experimental-and-theoretical-analysis
#5
M Węcławik, J Baran, P Durlak, Ł Marciniak, A Piecha-Bisiorek, R Jakubas
The paper presents the Infrared and Raman spectra of the powdered [C3N2H5(+)]2[I(-)∙I3(-)] crystal at the temperature intervals of 11-270K, covering two low-temperature phase transitions: discontinuous at 182/188K (cooling/heating) and continuous at 254K. The research shows that the vibrational states of the pyrazolium cations change significantly during discontinuous phase transition (III→II), while the continuous nature of successive structural transformation is more subtle and displays an insignificant change in the temperature coefficient of numerous vibrations during the II→I PT at 254K...
February 16, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28231130/evaluation-of-turmeric-powder-adulterated-with-metanil-yellow-using-ft-raman-and-ft-ir-spectroscopy
#6
Sagar Dhakal, Kuanglin Chao, Walter Schmidt, Jianwei Qin, Moon Kim, Diane Chan
Turmeric powder (Curcuma longa L.) is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman) and Fourier Transform-Infra Red (FT-IR) spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0...
May 17, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28229133/towards-enhanced-optical-sensor-performance-seira-and-sers-with-plasmonic-nanostars
#7
O Bibikova, J Haas, A I López-Lorente, A Popov, M Kinnunen, I Meglinski, B Mizaikoff
We report the preparation and characterization of plasmonic chip-based systems comprising self-assembled gold nanostars at silicon substrates that enable concomitantly enhanced Raman (surface enhanced Raman spectroscopy; SERS) and mid-infrared (surface enhanced infrared reflection or absorption spectroscopy; SEIRA) spectral signatures. The high-aspect-ratio structure of gold nanostars provides an increased number of hot spots at their surface, which results in an electric field enhancement around the nanomaterial...
February 23, 2017: Analyst
https://www.readbyqxmd.com/read/28228168/luminescence-spectroscopical-properties-of-plagioclase-particles-from-the-hayabusa-sample-return-mission-an-implication-for-study-of-space-weathering-processes-in-the-asteroid-itokawa
#8
Arnold Gucsik, Tomoki Nakamura, Cornelia Jäger, Kiyotaka Ninagawa, Hirotsugu Nishido, Masahiro Kayama, Akira Tsuchiyama, Ulrich Ott, Ákos Kereszturi
We report a systematic spectroscopical investigation of three plagioclase particles (RB-QD04-0022, RA-QD02-0025-01, and RA-QD02-0025-02) returned by the Hayabusa spacecraft from the asteroid Itokawa, by means of scanning electron microscopy, cathodoluminescence microscopy/spectroscopy, and micro-Raman spectroscopy. The cathodoluminescence properties are used to evaluate the crystallization effects and the degree of space weathering processes, especially the shock-wave history of Itokawa. They provide new insights regarding spectral changes of asteroidal bodies due to space weathering processes...
February 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28227296/fluorescence-background-removal-method-for-biological-raman-spectroscopy-based-on-empirical-mode-decomposition
#9
Maritza Leon-Bejarano, Guadalupe Dorantes-Mendez, Miguel Ramirez-Elias, Martin O Mendez, Alfonso Alba, Ildefonso Rodriguez-Leyva, M Jimenez, Maritza Leon-Bejarano, Guadalupe Dorantes-Mendez, Miguel Ramirez-Elias, Martin O Mendez, Alfonso Alba, Ildefonso Rodriguez-Leyva, M Jimenez, Ildefonso Rodriguez-Leyva, Alfonso Alba, M Jimenez, Martin O Mendez, Miguel Ramirez-Elias, Maritza Leon-Bejarano, Guadalupe Dorantes-Mendez
Raman spectroscopy of biological tissue presents fluorescence background, an undesirable effect that generates false Raman intensities. This paper proposes the application of the Empirical Mode Decomposition (EMD) method to baseline correction. EMD is a suitable approach since it is an adaptive signal processing method for nonlinear and non-stationary signal analysis that does not require parameters selection such as polynomial methods. EMD performance was assessed through synthetic Raman spectra with different signal to noise ratio (SNR)...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226214/selective-encaging-of-n2o-in-n2o-n2-binary-gas-hydrates-via-hydrate-based-gas-separation
#10
Youjeong Yang, Donghoon Shin, Seunghyun Choi, Yesol Woo, Jong-Won Lee, Dongseon Kim, Hee-Young Shin, Minjun Cha, Ji-Ho Yoon
The crystal structure and guest inclusion behaviors of nitrous oxide-nitrogen (N2O-N2) binary gas hydrates formed from N2O/N2 gas mixtures are determined through spectroscopic analysis. Powder X-ray diffraction results indicate that the crystal structure of all the N2O-N2 binary gas hydrates is identified as the structure I (sI) hydrate. Raman spectra for N2O-N2 binary gas hydrate formed from N2O/N2 (80/20, 60/40, 40/60 mol %) gas mixtures reveal that N2O molecules occupy both large and small cages of the sI hydrate...
February 22, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28224790/ph-dependent-photodeprotection-of-formaldehyde-homolytic-c-c-scission-in-acidic-aqueous-solution-versus-heterolytic-c-c-scission-in-basic-aqueous-solution
#11
Mingyue Liu, Wenjian Tang, Ming-De Li, David Lee Phillips
The photodeprotection of formaldehyde was investigated for 3-(1-hydroxypropan-2-yl)benzophenone (3-HPBP) with ultrafast time-resolved spectroscopy. The femtosecond transient absorption results indicated the singlet excited state of 3-HPBP transformed efficiently into its triplet state by a fast intersystem crossing. In acidic (pH=0) and basic (pH=12.5) aqueous solutions, the triplet intermediate was a key precursor for the deprotection of formaldehyde via two different pathways. However little photodeprotection was observed in neutral (pH=7) aqueous solution where the triplet intermediate appeared to undergo a proton coupled electron transfer process to form a ketyl radical transient...
February 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28224610/structural-changes-in-cartilage-and-collagen-studied-by-high-temperature-raman-spectroscopy
#12
Mark Fields, Nicholas Spencer, Jayesh Dudhia, Paul F McMillan
Understanding the high temperature behavior of collagen and collagenous tissue is important for surgical procedures and biomaterials processing for the food, pharmaceutical and cosmetics industries. One primary event for proteins is thermal denaturation that involves unfolding the polypeptide chains while maintaining the primary structure intact. Collagen in the extracellular matrix of cartilage and other connective tissue is a hierarchical material containing bundles of triple-helical fibers associated with water and proteoglycan components...
February 22, 2017: Biopolymers
https://www.readbyqxmd.com/read/28222259/band-alignment-at-gan-single-layer-wse2-interface
#13
Malleswararao Tangi, Pawan Mishra, Chien-Chih Tseng, Tien Khee Ng, Mohamed Nejib Hedhili, Dalaver H Anjum, Mohd Sharizal Alias, Nini Wei, Lain-Jong Li, Boon S Ooi
We study the band discontinuity at the GaN/single-layer (SL) WSe2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe2/c-sapphire. We confirm that the WSe2 was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron microscopy, micro-Raman, absorbance, and micro-photoluminescence spectra. The determination of band offset parameters at the GaN/SL-WSe2 heterojunction is obtained by high-resolution x-ray photoelectron spectroscopy, electron affinities and the electronic bandgap values of SL-WSe2 and GaN...
February 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28221789/raman-spectroscopy-reveals-selective-interactions-of-cytochrome-c-with-cardiolipin-that-correlate-with-membrane-permeability
#14
Jay P Kitt, David A Bryce, Shelley D Minteer, Joel M Harris
Permeabilization of the outer mitochondrial membrane is an integral step in apoptosis. The resulting release of pro-apoptotic signaling proteins leads to cell destruction through activation of the cysteine-aspartic protease (caspase) cascade. However, the mechanism of outer mitochondrial membrane (OMM) permeabilization remains unclear. It was recently shown that cytochrome c can induce pore formation in cardiolipin-containing phospholipid membranes leading to large dextran and protein permeability. In this work, the interaction of cytochrome c with cardiolpin-containing phospholipid vesicles, serving as models of the OMM, is investigated to probe cytochrome c-induced permeability...
February 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28221786/chemical-trends-in-solid-alkali-pertechnetates
#15
Jamie Weaver, Chuck Z Soderquist, Nancy M Washton, Andrew S Lipton, Paul L Gassman, Wayne W Lukens, Albert A Kruger, Nathalie A Wall, John S McCloy
Insight into the solid-state chemistry of pure technetium-99 ((99)Tc) oxides is required in the development of a robust immobilization and disposal system for nuclear waste stemming from the radiopharmaceutical industry, from the production of nuclear weapons, and from spent nuclear fuel. However, because of its radiotoxicity and the subsequent requirement of special facilities and handling procedures for research, only a few studies have been completed, many of which are over 20 years old. In this study, we report the synthesis of pure alkali pertechnetates (sodium, potassium, rubidium, and cesium) and analysis of these compounds by Raman spectroscopy, X-ray absorption spectroscopy (XANES and EXAFS), solid-state nuclear magnetic resonance (static and magic angle spinning), and neutron diffraction...
February 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28220852/transfer-of-monolayer-tmd-ws2-and-raman-study-of-substrate-effects
#16
Jerome T Mlack, Paul Masih Das, Gopinath Danda, Yung-Chien Chou, Carl H Naylor, Zhong Lin, Néstor Perea López, Tianyi Zhang, Mauricio Terrones, A T Charlie Johnson, Marija Drndić
A facile transfer process for transition metal dichalcogenide WS2 flakes is reported and the effect of the underlying substrate on the flake properties is investigated using Raman spectroscopy. The flakes are transferred from their growth substrate using polymethyl methacrylate (PMMA) and a wet etch to allow the user to transfer the flakes to a final substrate using a microscope and micromanipulator combined with semi-transparent Kapton tape. The substrates used range from insulators such as industry standard high-k dielectric HfO2 and "green polymer" parylene-C, to conducting chemical vapor deposition (CVD) grown graphene...
February 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28218847/raman-optical-activity-spectra-from-density-functional-perturbation-theory-and-density-functional-theory-based-molecular-dynamics
#17
Sandra Luber
We describe the calculation of Raman optical activity (ROA) tensors from density functional perturbation theory, which has been implemented into the CP2K software package. Using the mixed Gaussian and plane waves method, ROA spectra are evaluated in the double-harmonic approximation. Moreover, an approach for the calculation of ROA spectra by means of density functional theory-based molecular dynamics is derived and used to obtain an ROA spectrum via time correlation functions, which paves the way for the calculation of ROA spectra taking into account anharmonicities and dynamic effects at ambient conditions...
February 20, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28213313/structural-investigation-of-the-cocrystal-formed-between-5-fluorocytosine-and-fumaric-acid-based-on-vibrational-spectroscopic-technique
#18
Yong Du, Qiang Cai, Jiadan Xue, Qi Zhang, Dan Qin
The vibrational spectra of 5-fluorocytosine, fumaric acid and their cocrystal were measured using terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy at room temperature. Experimental THz results show that the cocrystal has distinct fingerprint spectra in terahertz region. The absorption peaks observed in the terahertz spectra of the cocrystal were at 0.61 and 0.91THz. These are quite different from corresponding raw starting materials. Raman spectra also show similar results about differences between the cocrystal and corresponding raw starting materials...
February 7, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28210735/the-dehydrogenation-mechanism-during-the-incubation-period-in-nanocrystalline-mgh2
#19
Apurva Shantilal Gangrade, Akhil Aditya Varma, Nikhil Kishor Gor, Sweta Shriniwasan, Sankara Sarma V Tatiparti
The dehydrogenation mechanism during the incubation period in nanocrystalline MgH2 (low α: converted metal fraction and dα/dt) and the reasons for the occurrence of the incubation period at 320, 350, and 400 °C were investigated. Pre-existing Mg crystallites can enhance Mg nucleation during the incubation period, as suggested by the estimated activation energy for nucleation (12 ± 2 kJ per mol H). The released H-atoms enter MgH2 as interstitials, as indicated by the MgH2 unit-cell contraction, resulting in increased equatorial Mg-H bond length, decreased charge-density distribution in the interstitial region, as observed from the charge-density maps, and decreased H-H distance in the {001} plane up to the midway of the incubation period...
February 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28208285/determining-gender-by-raman-spectroscopy-of-a-bloodstain
#20
Aliaksandra Sikirzhytskaya, Vitali Sikirzhytski, Igor K Lednev
The development of novel methods for forensic science is a constantly growing area of modern analytical chemistry. Raman spectroscopy is one of a few analytical techniques capable of nondestructive and nearly instantaneous analysis of a wide variety of forensic evidence, including body fluid stains, at the scene of a crime. In this proof-of-concept study, Raman microspectroscopy was utilized for gender identification based on dry bloodstains. Raman spectra were acquired in mapping mode from multiple spots on a bloodstain to account for intrinsic sample heterogeneity...
February 7, 2017: Analytical Chemistry
keyword
keyword
86995
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"