scholarly journals Raman Spectroscopy for Quantitative Analysis of Point Defects and Defect Clusters in Irradiated Graphite

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Keisuke Niwase
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Raman Spectra ◽  
Intensity Ratio ◽  
Irradiation Time ◽  
Amorphous State ◽  
Raman Intensity ◽  
Defect Clusters ◽  
Accumulation Model ◽  
Irradiated Graphite

We report the development of Raman spectroscopy as a powerful tool for quantitative analysis of point defect and defect clusters in irradiated graphite. Highly oriented pyrolytic graphite (HOPG) was irradiated by 25 keV He+ and 20 keV D+ ions. Raman spectroscopy and transmission electron microscopy revealed a transformation of irradiated graphite into amorphous state. Annealing experiment indicated a close relation between Raman intensity ratio and vacancy concentration. The change of Raman spectra under irradiation was empirically analyzed by “disordered-region model,” which assumes the transformation from vacancy-contained region to disordered region. The model well explains the change of Raman spectra and predicts the critical dose of amorphization, but the nature of the disordered region is unclear. Then, we advanced the model into “dislocation accumulation model,” assigning the disordered region to dislocation dipole. Dislocation accumulation model can simulate the irradiation time dependencies of Raman intensity ratio and the c-axis expansion under irradiation, giving a relation between the absolute concentration of vacancy and Raman intensity ratio, suggesting an existence of the barrier on the mutual annihilation of vacancy and interstitial.

scholarly journals Cryogenic Raman Spectroscopic Studies on Common Ore-forming Fluid Systems

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 363
Author(s):  
Dan Yang ◽  
Xin Xiong ◽  
Weishi Chen
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Correlation Coefficient ◽  
Fluid Inclusions ◽  
Intensity Ratio ◽  
Spectroscopic Studies ◽  
Ore Deposits ◽  
Raman Spectroscopic ◽  
Freezing Method ◽  
Fluid Systems

The composition and properties of ore-forming fluids are key to understanding the mechanisms of mineralization in ore deposits. These characteristics can be understood by studying fluid inclusions. Hydrates in fluid inclusions containing NaCl–H2O and MgCl2–H2O were studied using cryogenic Raman spectroscopy. The intensity ratio of peaks at 3401, 3464, 3514, and 3090 cm−1 shows a positive correlation with the concentration of hydrates in the inclusions, as does the ratio of the total integrated area of the MgCl2 hydrate peak (3514 cm−1) to the 3090 cm−1 peak with the concentration of MgCl2 (correlation coefficient >0.90). These correlations are important in the quantitative analysis of MgCl2 in synthetic and natural NaCl–MgCl2–CaCl2–H2O-bearing fluid inclusions. Semi-quantitative analysis of NaCl–MgCl2–H2O solutions indicates that peaks at 3437 and 3537 cm−1 reflect the presence of NaCl in the solution. Further, a peak at 3514 cm−1 is indicative of the presence of MgCl2. The relative intensities of these peaks may be related to the relative abundances of NaCl and MgCl2. A quantitative attempt was made on NaCl–MgCl2–CaCl2–H2O system, but it was found that quantifying NaCl, MgCl2 and CaCl2 separately in NaCl–MgCl2–CaCl2–H2O system by the secondary freezing method is difficult.

scholarly journals MICRO RAMAN SPECTROSCOPIC ANALYSIS OF LOBULAR CARCINOMA TISSUES

2018 ◽  
Vol 11 (9) ◽  
pp. 172
Author(s):  
Ambili Reveendran ◽  
Sanoj Varghese ◽  
Senthil Kumar V ◽  
Venkatesan Ranganathan ◽  
Karthikeyan Tm
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Intensity Ratio ◽  
Prophylactic Mastectomy ◽  
Lobular Carcinoma ◽  
Research Work ◽  
Intensity Variation ◽  
Tumor Formation ◽  
Biochemical Changes ◽  
Spectroscopic Techniques

Objective: For the past 20 decades, vibrational spectroscopy based studies are undergoing around the world to detect cancer at the earliest stage. Since vibrational spectroscopic techniques have the ability to measure the biochemical changes occur during the time of mutation, which may be the reason for cell proliferation. Biochemical changes may appear in the tissues and blood before the tumor formation. The objective of this work is to study the potential of Raman spectroscopy to detect biochemical changes in the normal and malignant tissues.Methods: In this research work, 10 Raman spectra were acquired from ex vivo samples of human breast tissue (normal and lobular carcinoma) of 10 patients after the removal during prophylactic mastectomy surgery and biopsy. Data analysis was performed using k-means clustering using SPSS and intensity ratio analysis.Result: Intensity variation in the Raman spectra of normal and malignant tissues clearly indicate that Raman spectra are capable to distinguish between normal and malignant tissues. A number of peaks are more in the case of malignant tissues and the presence of amide I and amide III indicate the predominance of protein in malignant tissues. Intensity ratio analysis and K-means clustering analysis also show the significance of protein in lobular carcinoma tissues.Conclusion: This research work proves the potential of Raman spectroscopy to differentiate between the normal breast tissues and lobular carcinoma tissues.

scholarly journals Novel Quantitative Analysis Using Optical Imaging (VELscope) and Spectroscopy (Raman) Techniques for Oral Cancer Detection

Cancers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3364
Author(s):  
Ming-Jer Jeng ◽  
Mukta Sharma ◽  
Lokesh Sharma ◽  
Shiang-Fu Huang ◽  
Liann-Be Chang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Discriminant Analysis ◽  
Oral Cancer ◽  
Raman Spectra ◽  
Cross Validation ◽  
Error Rates ◽  
Control Group ◽  
Optical Techniques ◽  
Linear Discriminant

In this study, we developed a novel quantitative analysis method to enhance the detection capability for oral cancer screening. We combined two different optical techniques, a light-based detection technique (visually enhanced lesion scope) and a vibrational spectroscopic technique (Raman spectroscopy). Materials and methods: Thirty-five oral cancer patients who went through surgery were enrolled. Thirty-five cancer lesions and thirty-five control samples with normal oral mucosa (adjacent to the cancer lesion) were analyzed. Thirty-five autofluorescence images and 70 Raman spectra were taken from 35 cancer and 35 control group cryopreserved samples. The normalized intensity and heterogeneity of the 70 regions of interest (ROIs) were calculated along with 70 averaged Raman spectra. Linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA) were used with principal component analysis (PCA) to differentiate the cancer and control groups (normal). The classifications rates were validated using two different validation methods, leave-one-out cross-validation (LOOCV) and k-fold cross-validation. Results: The cryopreserved normal and tumor tissues were differentiated using the PCA–LDA and PCA–QDA models. The PCA–LDA of Raman spectroscopy (RS) had 82.9% accuracy, 80% sensitivity, and 85.7% specificity, while ROIs on the autofluorescence images were differentiated with 90% accuracy, 100% sensitivity, and 80% specificity. The combination of two optical techniques differentiated cancer and normal group with 97.14% accuracy, 100% sensitivity, and 94.3% specificity. Conclusion: In this study, we combined the data of two different optical techniques. Furthermore, PCA–LDA and PCA–QDA quantitative analysis models were used to differentiate tumor and normal groups, creating a complementary pathway for efficient tumor diagnosis. The error rates of RS and VELcope analysis were 17.10% and 10%, respectively, which was reduced to 3% when the two optical techniques were combined.

Backside Monitoring of Graphene on Silicon Carbide by Raman Spectroscopy

2014 ◽  
Vol 778-780 ◽  
pp. 1166-1169
Author(s):  
Felix Fromm ◽  
Martin Hundhausen ◽  
Michl Kaiser ◽  
Thomas Seyller
Keyword(s):  
Silicon Carbide ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Graphene Layer ◽  
Scattered Light ◽  
Epitaxial Graphene ◽  
Raman Intensity ◽  
Top Down ◽  
Measurement Geometry

Raman spectroscopy is commonly applied for studying the properties of epitaxial graphene on silicon carbide (SiC). In principle, the Raman intensity of a single graphene layer is rather low compared to the signal of SiC. In this work we follow an approach to improve the Raman intensity of epitaxial graphene on SiC by recording Raman spectra in a top-down geometry, i.e. a geometry in which the graphene layer is probed with the excitation through the SiC substrate [1]. This technique takes advantage of the fact, that most of the Raman scattered light of the graphene is emitted into the SiC substrate. We analyze in detail the top-down measurement geometry regarding the graphene and SiC Raman intensity, as well as the influence of aberration effects caused by the refraction at the air/SiC interface.

Investigation of the Morphological Composition of Cimetidine by FT-Raman Spectroscopy

1995 ◽  
Vol 49 (8) ◽  
pp. 1142-1145 ◽  
Author(s):  
George Jalsovszky ◽  
Orsolya Egyed ◽  
Sándor Holly ◽  
Béla Hegedus
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Least Squares ◽  
Partial Least Squares ◽  
Raman Spectra ◽  
Crystal Forms ◽  
Morphological Composition ◽  
Ft Raman Spectroscopy ◽  
Mathematical Techniques ◽  
Ft Raman

The Raman spectra of six polymorphic crystal forms of N-cyano- N′-methyl- N″-{2-[(5-methyl-1H-imidazol-4-yl)methylthio]ethyl}-guanidine (Cimetidine) have been studied to investigate the possibility of quantitative analysis of polymorphic mixtures. Characteristic Raman bands of the various polymorphs have been found, some of which proved to be appropriate for quantitative analysis. The applicability of various mathematical techniques has been investigated, of which partial least-squares (PLS) has been found to be the best.

Raman studies of Pd-C nanocomposites

Open Physics ◽  
2013 ◽  
Vol 11 (2) ◽  
Author(s):  
Radoslaw Belka ◽  
Malgorzata Suchanska ◽  
Elzbieta Czerwosz ◽  
Justyna Keczkowska
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Raman Spectra ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
C60 Fullerene ◽  
Physical Vapour Deposition ◽  
Percentage Content ◽  
One Step ◽  
Palladium Content

AbstractThe results of studying palladium-carbon (Pd-C) nanocomposites using Raman spectroscopy are presented. This method has been used for studying samples having various palladium content, prepared by a one-step Physical Vapour Deposition (PVD) process and a Chemical Vapour Deposition (two-step PVD/CVD) process using different process parameters. For samples obtained by PVD, the vibration bands characteristic of C60 fullerene molecules were observed in the spectra, whereas for layers obtained by PVD/CVD, the Raman spectra displayed mainly D and G bands characteristic solely of the prescence of graphite-like layers’ vibrations. The analysis of the obtained Raman spectra reveals that its shape is affected by many parameters including type of substrate, temperature, and the percentage content of Pd in the studied layer. The quantitative analysis of spectra for layers obtained using the PVD/CVD process shows a difference in the relative intensity of bands D and G, reflecting the different degrees of amorphisation in the investigated nanocomposites.

Raman Tensor of Graphite: Symmetry of G, D and D' Phonons

2021 ◽  
Author(s):  
Mingge Jin ◽  
Lu Cheng ◽  
Wei Zheng ◽  
Ying Ding ◽  
Yanming Zhu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Experimental Evidence ◽  
Raman Spectra ◽  
First Record ◽  
Raman Intensity ◽  
Physical Origin ◽  
Angle Dependence ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman ◽  
Resonant Mechanism

Abstract Since the first record of Raman spectra of graphite in 1970, the physical origin behind its Raman characteristic peaks (i.e., G, D and D' peaks) has been a focus of controversy. At present, it is generally believed that G peak corresponds to Raman active E 2g2 mode, while D and D' peaks are defect-induced ones. However, unequivocal experimental evidence for the phonon symmetries for these graphite Raman peaks is almost still in blank. Here, we clarify these important aspects using an angle resolved polarized Raman spectroscopy. It is found that the experimental Raman intensity of D and D' peaks shows a similar polarized angle dependence as that of G peak. Combined with Raman tensor analysis and double-resonant mechanism, the phonon symmetry of D' and D peak is further understood. Our work provides reliable experimental evidence and reasonable explanation for better understanding the phonon symmetry of graphite.

Biological Applications of Anti-Stokes Raman Spectroscopy: Quantitative Analysis of Glucose in Plasma and Serum by a Highly Sensitive Multichannel Raman Spectrometer

1996 ◽  
Vol 50 (10) ◽  
pp. 1301-1306 ◽  
Author(s):  
Xiaoming Dou ◽  
Yoshinori Yamaguchi ◽  
Hiroshi Yamamoto ◽  
Harumi Uenoyama ◽  
Yukihiro Ozaki
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Biological Samples ◽  
Biological Sample ◽  
Chromatic Aberration ◽  
Raman Intensity ◽  
Biological Applications ◽  
High Quality ◽  
Highly Sensitive ◽  
Anti Stokes

This study demonstrates the potential of anti-Stokes Raman spectroscopy in investigating biological samples in a nondestructive manner; quantitative analysis of glucose in plasma and serum has been studied as an example. The efficient collection of anti-Stokes Raman scattering by use of chromatic aberration of a lens has allowed us to obtain high-quality anti-Stokes Raman spectra from glucose in plasma and serum, which is a strongly fluorescent biological sample. The concentration of glucose in these materials can be estimated by the anti-Stokes Raman intensity of the band at 1130 cm−1 due to the C–O stretching mode. The correlation coefficient between the concentration and the intensity has been calculated to be 0.993 and 0.991 for glucose in plasma and serum, respectively. The detection limits for these materials have been found to be 45 mg/dL and 50 mg/dL, respectively.

The Application of Raman Spectroscopy to Chemical Analysis

1971 ◽  
Vol 25 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D. E. Irish ◽  
H. Chen
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Ir Spectroscopy ◽  
Chemical Analysis ◽  
Raman Spectra ◽  
Laser Excitation ◽  
Mercury Lamp

The development of the laser and its application as a source for the excitation of Raman spectra have resulted in the availability of Raman spectrophotometers at a cost competitive with ir spectroscopy. Quantitative analysis is a natural application. Procedures utilized with the conventional mercury lamp excitation and problems associated with laser excitation are reviewed. A bibliography of analyses is included.

Submicron Simultaneous IR and Raman Spectroscopy (IR+Raman): Breakthrough Developments in Optical Photothermal IR (O-PTIR) Combined for Enhanced Failure Analysis

2019 ◽  
Author(s):  
Jay Anderson ◽  
Mustafa Kansiz ◽  
Michael Lo ◽  
Curtis Marcott
Keyword(s):  
Raman Spectroscopy ◽  
Failure Analysis ◽  
Data Quality ◽  
Raman Spectra ◽  
Spatial Resolution ◽  
Far Field ◽  
Field Mode ◽  
Microscopic Scale ◽  
Analytical Tools ◽  
Ir And Raman

Abstract Failure analysis of organics at the microscopic scale is an increasingly important requirement, with traditional analytical tools such as FTIR and Raman microscopy, having significant limitations in either spatial resolution or data quality. We introduce here a new method of obtaining Infrared microspectroscopic information, at the submicron level in reflection (far-field) mode, called Optical-Photothermal Infrared (O-PTIR) spectroscopy, that can also generate simultaneous Raman spectra, from the same spot, at the same time and with the same spatial resolution. This novel combination of these two correlative techniques can be considered to be complimentary and confirmatory, in which the IR confirms the Raman result and vice-versa, to yield more accurate and therefore more confident organic unknowns analysis.

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