scholarly journals Raman Spectra of Nanodiamonds: New Treatment Procedure Directed for Improved Raman Signal Marker Detection

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Raoul R. Nigmatullin ◽  
Dumitru Baleanu ◽  
Diana Povarova ◽  
Numan Salah ◽  
Sami S. Habib ◽  
...  
Keyword(s):  
Raman Spectra ◽  
High Refractive Index ◽  
Spectroscopic Studies ◽  
Raman Signal ◽  
Heating Rates ◽  
Inert Core ◽  
Optimal Linear ◽  
Linear Smoothing ◽  
New Treatment ◽  
Increasing Temperature

Detonation nanodiamonds (NDs) have shown to be promising agents in several industries, ranging from electronic to biomedical applications. These NDs are characterized by small particle size ranging from 3 to 6 nm, while having a reactive surface and a stable inert core. Nanodiamonds can exhibit novel intrinsic properties such as fluorescence, high refractive index, and unique Raman signal making them very attractive imaging agents. In this work, we used several nanodiamond preparations for Raman spectroscopic studies. We exposed these nanodiamonds to increasing temperature treatments at constant heating rates (425–575°C) aiding graphite release. We wanted to correlate changes in the nanodiamond surface and properties with Raman signal which could be used as adetection marker. These observations would hold potential utility in biomedical imaging applications. First, the procedure of optimal linear smoothing was applied successfully to eliminate the high-frequency fluctuations and to extract the smoothed Raman spectra. After that we applied the secondary Fourier transform as the fitting function based on some significant set of frequencies. The remnant noise was described in terms of the beta-distribution function. We expect this data treatment to provide better results in biomolecule tracking using nanodiamond base Raman labeling.

Quantitative Analysis of Raman Spectra in Si/SiGe Nanostructures

2013 ◽  
Vol 1510 ◽  
Author(s):  
Selina Mala ◽  
Leonid Tsybeskov ◽  
Jean-Marc Baribeau ◽  
Xiaohua Wu ◽  
David J. Lockwood
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Quantitative Analysis ◽  
Raman Spectra ◽  
Instrumental Response ◽  
Sample Surface ◽  
Stray Light ◽  
Raman Signal ◽  
Longitudinal Acoustic ◽  
Local Sample

ABSTRACTWe present comprehensive quantitative analysis of Raman spectra in two-(Si/SiGe superlattices) and three-(Si/SiGe cluster multilayers) dimensional nanostructures. We find that the Raman spectra baseline is due to the sample surface imperfection and instrumental response associated with the stray light. The Raman signal intensity is analyzed, and Ge composition is calculated and compared with the experimental data. The local sample temperature and thermal conductivity are calculated, and the spectrum of longitudinal acoustic phonons is explained.

Spectroscopic Studies of a Superionic Plastic Phase Crystal: Lithium Sulfate

1988 ◽  
Vol 135 ◽  
Author(s):  
Roger Frech
Keyword(s):  
Lithium Ion ◽  
Spectroscopic Studies ◽  
Lithium Sulfate ◽  
Sulfate Ion ◽  
Raman Spectroscopic ◽  
Ion Interactions ◽  
Energy Environment ◽  
Plastic Phase ◽  
Bending Modes ◽  
Increasing Temperature

AbstractTemperature dependent Raman spectroscopic studies of single crystal lithium sulfate are summarized. Coupling between sulfate ion bending modes and the lithium ion translatory modes becomes weaker with increasing temperature until the lithium modes can no longer be observed above 250° C. The temperature interval above 450° in the monoclinic phase is marked by the onset of significant sulfate ion reorientational motion, as evidenced by the bandshape studies of the sulfate ion v1, mode and the librational modes. Bandshape analysis of the v3mode in the plastic phase strongly suggests that the symmetry of the sulfate ion potential energy environment has planar anisotropy.The lithium ion-sulfate ion interactions are modeled for correlated sulfate ion configurations as a function of lithium ion position. The results support the role of the octahedral site in lithium ion transitions contributing to the ionic conductivity.

scholarly journals Raman Spectroscopy and Statistical Analysis of the Silicate Species and Group Connectivity in Cesium Silicate Glass Forming System

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Armenak Osipov ◽  
Leyla Osipova ◽  
Rimma Zainullina
Keyword(s):  
Experimental Data ◽  
Raman Spectroscopy ◽  
Statistical Analysis ◽  
Raman Spectra ◽  
Dynamic Equilibrium ◽  
Structural Units ◽  
Melt Temperature ◽  
Deconvolution Analysis ◽  
Glass Forming ◽  
Increasing Temperature

The Raman spectra of x%Cs2O-(100 − x)%SiO2 (x=17, 22, 27, 33, and 37 mol%) glasses and melts were measured in the temperature range of 293 to 1553 K. The concentrations of the Qn species were calculated as a function of the composition and temperature based on the deconvolution analysis of the spectra. It was found that a dynamic equilibrium among structural units in the melts with x>17 mol% can be described by disproportionation reaction Q3⇔Q4+Q2. The enthalpy of this reaction was found to be equal to 32 ± 6, 43 ± 8, 56 ± 10, and 52 ± 9 for x=22, 27, 33, and 37 mol%, respectively. The nonideal entropy of mixing (ΔSmix) depends on the melt temperature and increases almost linearly with increasing temperature. The Qn, Q2–Q2, and Qn,ijkl distributions with x ranging from 0 to 55 mol% were modeled using experimental data for the concentrations of the Qn units.

Chemical and spectroscopic studies of blue flames in the auto-ignition of methane

1955 ◽  
Vol 230 (1180) ◽  
pp. 1-19 ◽  
Keyword(s):  
Spectroscopic Studies ◽  
Compression Ignition ◽  
Low Temperature Oxidation ◽  
Compression Ignition Engine ◽  
Temperature Oxidation ◽  
Carbon Particles ◽  
Cool Flames ◽  
Auto Ignition ◽  
Increasing Temperature ◽  
Normal Flame

A blue pre-ignition glow has been found with weak methane + air mixtures, using a motored compression-ignition engine with fixed compression ratio and speed; the temperature was controlled by preheating the inlet air. The limits of the glow and its transition to normal flame have been studied. Analyses of exhaust products and records of pressure and luminosity have been made. The spectrum of the glow shows formaldehyde bands, normally associated with cool flames. As the normal ignition limit is approached this spectrum changes smoothly, with increasing temperature or mixture strength, to a normal flame spectrum showing OH, CH and HCO bands. Using a stroboscope we have found slight indication that the CH 2 O bands precede the CH and OH. Less lean mixtures show yellow luminosity, associated with carbon particles. The possibilities that the CH 2 O emission results from polymerization of the methane, from partial oxidation to methyl alcohol, or directly from a cool-flame phenomenon in methane, are discussed in relation to conditions in the combustion chamber. The new observation of CH 2 O bands from methane may be interpreted in favour of its formation by reactions of methoxy radicals. Methane is known to knock in an engine at high compression ratios. Present results suggest that low-temperature oxidation processes may, as with other hydrocarbons, contribute to this knock.

Illumination- and Annealing-Induced Changes in the Infrared and Raman Spectra of a-Si:H

2001 ◽  
Vol 664 ◽  
Author(s):  
L.-F. Arsenault ◽  
S. Lebiba ◽  
E. Sacher ◽  
A. Yelon
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Qualitative Agreement ◽  
Raman Signal ◽  
Infrared And Raman Spectra ◽  
Matrix Elements ◽  
Short Term ◽  
Phonon Peak ◽  
Induced Changes ◽  
Ir And Raman

ABSTRACTWe have investigated the changes, produced by light-soaking, in both the IR and Raman responses of the Si-Hn stretching peaks in the 2000-2100 cm−1 range. Our observations of the IR response are in qualitative agreement with those of Kong and co-workers [1]: that is, short-term light soaking produces an increase in the intensity of the signal and a simultaneous shift to lower frequency. In contrast, short-term light soaking decreases the total intensity of the Raman signal in the 2000-2100 cm−1 range, when normalized to the TO phonon peak at about 480 cm−1. In both cases, these modifications are reversed on annealing at 200° C. We suggest that these changes are attributable to alterations in the environments of the Si-Hn bonds, with the resultant transfer of intensity between IR and Raman matrix elements. Details of the evolution of the components of the Raman spectrum in the 2000-2100 cm−1 range are presented, and compared with IR changes in the same range.

Raman Spectroscopic Studies of the Vulcanization of Rubbers. III. Studies of Vulcanization Systems Based on 2-Mercaptobenzothiazole

1972 ◽  
Vol 45 (1) ◽  
pp. 173-181 ◽  
Author(s):  
M. M. Coleman ◽  
J. R. Shelton ◽  
J. L. Koenig
Keyword(s):  
Raman Spectra ◽  
Raman Line ◽  
Lauric Acid ◽  
Spectroscopic Studies ◽  
Type I ◽  
Raman Spectroscopic ◽  
Major Significance ◽  
Sulfur Vulcanization ◽  
Cyclic Sulfide

Abstract The shoulder observed at approximately 440 cm−1 in Raman spectra of CB vulcanizates prepared from MBT based vulcanizing systems has been shown to consist of two components. There are Raman lines contributing at 440 cm−1 and 424 cm−1. The former is due to ZnO present as an extra-network material while the latter appears to be associated with polysulfidic structures. The Raman line at 505 cm−1 seen in extracted vulcanizates prepared from CB-MBT-Sulfur-ZnO-Lauric acid recipes does not appear to be solely due to disulfidic structures. The major contribution appears to be associated with an unsaturated cyclic sulfide and is most probably due to a structure of the type (I). If the assignment to cyclic sulfidic structures such as (I) is confirmed, it will have major significance with regard to the mechanism of accelerated sulfur vulcanization.

Resonance Raman labels: spectroscopic studies on cis- and trans-4-benzylidene-2-phenyl-Δ2 -oxazolin-5-one and an isotopically substituted analog

1978 ◽  
Vol 56 (2) ◽  
pp. 232-239 ◽  
Author(s):  
K. Kumar ◽  
D. J. Phelps ◽  
P. R. Carey
Keyword(s):  
Raman Spectra ◽  
Electronic Transition ◽  
Raman Band ◽  
Resonance Raman ◽  
Spectroscopic Studies ◽  
Trans Isomers ◽  
Absorption Bands ◽  
Cis And Trans Isomers ◽  
Raman Excitation Profiles ◽  
Cis And Trans

The absorption and preresonance Raman spectra of cis- and trans-4-benzylidene-2-phenyl-Δ2-oxazoIin-5-one are reported. Although steric considerations suggest that the π electron pathway in the cis isomer is considerably distorted compared to the trans isomer, the Raman and absorption spectra of the two isomers are strikingly similar. Preresonance Raman excitation profiles for the cis and trans isomers indicate that the main features in the Raman spectra owe their intensity to coupling to the 360 nm absorption band present in both isomers. It is proposed that both the electronic dipole transition responsible for this absorption and the vibrational modes giving rise to the intense Raman bands are localized in the —C=C—N=C—Ph part of the molecule. Thus the main Raman and absorption bands are insensitive to isomerization in the benzylidene portion. Support for a localized electronic transition, polarized along the —C=C—N=C—Ph long axis, comes from Raman depolarization ratio (ρ) measurements which show that ail intense Raman features in both cis and trans isomers have ρ ∼ 0.33. Further support comes from ir and resonance Raman spectra of trans-4-(4-dimethylamino-3-nitrobenzylidene)-2-phenyloxazolin-5-one substituted either with 13C in the 4 position, or with 15N, in the oxazolinone ring. These spectra indicate that the main Raman feature seen in all 4-benzylidene-2-phenyloxazolinonesat 1561 cm−1 is a symmetric stretching mode associated with the —C=C—N=C— chain and that this feature has some C=N stretching character. The substitution experiments also show that the weak 1654 cm−1 Raman band has a high degree of C=C stretching character and may represent an essentially antisymmetric mode from the C=C—N=C moiety. The preresonance Raman excitation profiles show that the intensity enhancement follows an FB2 type dependence. The utility of the Raman spectrum as a probe for the chromophore responsible for the electronic transition in a highly conjugated system is discussed.

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