Raman Spectroscopy Allows for the Determination of Elephant Ivory Age

2020 ◽  
Vol 74 (8) ◽  
pp. 940-947
Author(s):  
Anna Sharikova ◽  
Lubna Peerzada ◽  
Kai Pisila ◽  
Tine Chean Khoo ◽  
Alexander Cherkinsky ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Raman Signal ◽  
Nondestructive Technique ◽  
Data Set ◽  
Portable System ◽  
Vibrational Bands ◽  
Elephant Ivory ◽  
Value Decomposition

Determination of the age of ivory is important for controlling illegal trafficking and the proper identification of ivory artifacts. Radiocarbon dating is the standard method of determining the age of ivories; however, it requires the destruction of a fragment of the sample. Raman spectroscopy is a nondestructive technique, and therefore can be used on artwork. Moreover, Raman measurements can be done using a portable system, and the data analysis can be performed on the spot once the groundwork is done. Ivories contain two primary components: collagen and bioapatite. Raman spectrum of ivory material is mainly a sum of the vibrational bands of these components. As collagen deteriorates with time, its Raman signal decreases; therefore, the ratio of collagen to bioapatite peaks is smaller in the older samples compared to the younger ones, providing a basis for sample dating. We have compared the results of Raman and radiocarbon measurements applied to a set of elephant ivory fragments and have successfully calibrated the Raman data set using radiocarbon measurements. We found that the Raman collagen to bioapatite peak ratios of the samples can be used as a metric to determine their age, providing a nondestructive technique to assess the age of ivory samples. We have also used singular value decomposition (SVD) to analyze the whole Raman spectra. We have observed clear separation between samples of different ages in the SVD component space. The samples also tended to align along the timeline diagonal in the correct order. The changes in multiple collagen and bioapatite peaks contribute to the differences in Raman spectra of ivory samples of different age.

Raman Spectra of Human Dental Calculus

1993 ◽  
Vol 72 (12) ◽  
pp. 1609-1613 ◽  
Author(s):  
H. Tsuda ◽  
J. Arends
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Octacalcium Phosphate ◽  
Spot Size ◽  
Spectral Features ◽  
Dental Calculus ◽  
Micro Raman Spectroscopy ◽  
Vibrational Bands ◽  
First Time ◽  
Mineral Constituents

Raman spectra of human dental calculus have been observed for the first time by use of micro-Raman spectroscopy. The spectral features of calculus were influenced easily by heating caused by laser irradiation. Therefore, the measurements were carried out at relatively low power (5 mW, 1-μm spot size). The spectra could be characterized as phosphate vibrational bands due to the v1, v2, v 3, and v4 modes. The overall spectral features did not resemble those of pure minerals such as brushite, octacalcium phosphate, and hydroxyapatite. There were spectral differences among mixed calculus particles obtained from 18 adults, probably due to variations in local mineral composition and differences among patients. However, the averaged spectral features did not vary significantly with formation period from 1 to 6 months. Freshly removed and stored (5-11 months) calculus also gave comparable Raman spectra. Measurements on a fractured sample indicated that Raman spectra at saliva and dentin interfaces are nearly identical, and major mineral constituents may not vary significantly along the growth axis of calculus.

Heating Effects of Desi Ghee Using Raman Spectroscopy

2018 ◽  
Vol 72 (6) ◽  
pp. 833-846 ◽  
Author(s):  
Naveed Ahmad ◽  
Muhammad Saleem ◽  
Mushtaq Ahmed ◽  
Shaukat Mahmood
Keyword(s):  
Principal Component Analysis ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Principal Component ◽  
Nondestructive Technique ◽  
Molecular Changes ◽  
Spectral Bands ◽  
Heating Effects ◽  
Excitation Laser ◽  
First Time

Raman spectroscopy as a fast and nondestructive technique has been used to investigate heating effects on Desi ghee during frying/cooking of food for the first time. A temperature in the range of 140–180℃ has been investigated within which Desi ghee can be used safely for cooking/frying without much alteration of its natural molecular composition. In addition, heating effects in case of reuse, heating for different times, and cooking inside pressure cookers are also presented. An excitation laser at 785 nm has been used to obtain Raman spectra and the range of 540–1800 cm−1 is found to contain prominent spectral bands. Prominent variations have been observed in the Raman bands of 560–770 cm−1, 790–1160 cm−1, and 1180–1285 cm−1 with the rise in temperature. The spectral variations have been verified using classifier principal component analysis. It has been found that Desi ghee can be reused if heated below 180℃ and it can be heated up to 30 min without any appreciable molecular changes if a controlled heating can be managed.

scholarly journals Subsurface and Transcutaneous Raman Spectroscopy and Mapping Using Concentric Illumination Rings and Collection with a Circular Fiber-Optic Array

2007 ◽  
Vol 61 (7) ◽  
pp. 671-678 ◽  
Author(s):  
Matthew V. Schulmerich ◽  
Kathryn A. Dooley ◽  
Thomas M. Vanasse ◽  
Steven A. Goldstein ◽  
Michael D. Morris
Keyword(s):  
Raman Spectra ◽  
Fiber Optic ◽  
Spatial Information ◽  
Raman Signal ◽  
Signal Recovery ◽  
Data Set ◽  
Exposed Bone ◽  
Circular Fiber ◽  
Single Data ◽  
Optic Array

Different spatial separations between an illumination ring and a bundle of 50 collection fibers focused to collect light in the center of the ring were used to investigate the recovery of subsurface Raman spectra. The depth of Raman signal recovery and the preservation of spatial information in the recovered signal were investigated using polymer blocks stacked in different geometries. The illumination rings were then combined into a single data set to increase variation in the signal. Multivariate data analysis was used to recover the Raman spectra of the subsurface component. The Raman spectrum of a Delrin target was recoverable at depths up to 22.6 mm of overlying Teflon. Spatial information was lost at approximately 6.5 mm below the Teflon surface. The same protocols were used to recover canine bone spectra transcutaneously at depths up to 5 mm below the skin's surface. The recovered bone spectra were validated by exposed bone measurements.

Determination of the Resolution of a Multichannel Raman Spectrometer Using Fourier Transform Raman Spectra

2003 ◽  
Vol 57 (2) ◽  
pp. 190-196 ◽  
Author(s):  
Bryan T. Bowie ◽  
Peter R. Griffiths
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Raman Spectra ◽  
Shape Function ◽  
Raman Spectrometer ◽  
Fourier Transform Raman ◽  
Nominal Resolution ◽  
Line Shape Function ◽  
Ft Raman

The resolution of a grating polychromator for Raman spectroscopy has been simulated by measuring spectra on a Fourier transform (FT) Raman spectrometer and selecting the FT of the apodization function so that the instrument line shape function mimics the triangular spectral slit function of the polychromator. To this end, FT-Raman spectra measured with a nominal resolution of 0.5 cm−1 were modified through the application of sinc2 apodization functions of various widths to simulate spectra measured on a polychromator at lower resolution. The success of this approach was validated using the 1085 cm−1 band of calcite. When the modified FT-Raman spectra were compared with spectra measured on a grating polychromator equipped with slits of widths 100 and 150 μm, the resolution of the polychromator was estimated to be 6.3 and 7.8 cm−1, respectively. This conclusion was verified experimentally by measuring the separation of two bands in the Raman spectrum of BaSO4 at ∼460 cm−1

Numerical Simulations of Subsurface Probing in Diffusely Scattering Media Using Spatially Offset Raman Spectroscopy

2005 ◽  
Vol 59 (12) ◽  
pp. 1485-1492 ◽  
Author(s):  
P. Matousek ◽  
M. D. Morris ◽  
N. Everall ◽  
I. P. Clark ◽  
M. Towrie ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Numerical Simulations ◽  
Raman Spectra ◽  
Raman Signal ◽  
Scattering Media ◽  
Layer System ◽  
Elementary Model ◽  
Annular Geometry ◽  
Subsurface Layers ◽  
Signal Intensities

We present the first elementary model predicting how Raman intensities vary for a range of experimental variables for spatially offset Raman spectroscopy (SORS), a recently proposed technique for the effective retrieval of Raman spectra of subsurface layers in diffusely scattering media. The model was able to reproduce the key observations made from the first SORS experiments, namely the dependence of Raman signal intensities on the spatial offset between the illumination and collection points and the relative contributions to the overall spectrum from the top layer and sub-layer. The application of the SORS concept to a three-layer system is also discussed. The model also clearly indicates that an annular geometry, rather than a point-collection geometry, which was used in the earlier experiments, would yield much improved data.

Raman and FTIR Spectroscopy of Synthetic Amphiboles: I. The OH Librational Bands and the Determination of the OH-F Content of Richterites via Raman Spectroscopy

2020 ◽  
Author(s):  
Giancarlo Della Ventura ◽  
Frank C. Hawthorne ◽  
Boriana Mihailova ◽  
Armida Sodo
Keyword(s):  
Raman Spectroscopy ◽  
Ftir Spectroscopy ◽  
Raman Spectra ◽  
Energy Region ◽  
Low Energy ◽  
Reliable Estimation ◽  
A Site ◽  
Combination Bands ◽  
Two Peaks

Abstract Unpolarized FTIR and Raman spectra were collected in the regions 4000–4600 cm–1 (NIR) and 100–4000 cm–1 from previously synthesized and characterized amphiboles in the systems richterite–fluoro-richterite, potassic-richterite–potassic-fluoro-richterite, rubidium-richterite–rubidium-fluoro-richterite, and potassic-richterite–deuterated potassic-richterite. The NIR spectra of Na-, K-, and Rb-richterites have peaks at 4325, 4210 cm–1, and 3735–3730 cm–1. All three peaks decrease in intensity with increasing F content, indicating that the higher-energy peaks are combination bands involving the principal OH-stretch at 3735–3730 cm–1 and two OH-libration modes, the frequencies of which can be calculated from the relation ωcombination ≈ ωOH + ωlibration; these are 590 and 475 cm–1, respectively. The FTIR spectra of the richterite–fluoro-richterite and potassic-richterite–potassic-fluoro-richterite series show decreasing intensity and eventual disappearance of the band at ∼600 cm–1 with increasing F in accord with the assignment of this band as due to OH-libration. Raman spectra of the potassic-richterite–deuterated potassic-richterite amphiboles in the low-energy region show the disappearance of two peaks at 585 and 473 cm–1 that we have assigned to OH-libration modes. Collectively, these spectroscopic results indicate that there are two OH-libration modes at ∼590 and ∼475 cm–1 in these synthetic richterites and, by implication, in all monoclinic OH-bearing amphiboles with filled A sites. Similarly to FTIR, the relative intensities of the stretching modes associated with OH-A-OH and OH-A-F local configurations in the Raman spectra provide a reliable estimation of the F content in these A site-filled amphiboles.

Raman spectroscopic determination of phase evolutions in LiAlxCo1−xO2 battery materials

2001 ◽  
Vol 16 (1) ◽  
pp. 1-4 ◽  
Author(s):  
P. S. Dobal ◽  
R. S. Katiyar ◽  
M. S. Tomar ◽  
A. Hidalgo
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Raman Spectra ◽  
Sintering Temperature ◽  
Monoclinic Space Group ◽  
Battery Materials ◽  
Space Group ◽  
Raman Spectroscopic ◽  
Al Content

Superior battery materials LiAlxCo1−xO2 (x = 0.0, 0.1, 0.3, 0.5, and 0.7) were synthesized using a solution-based route at various sintering temperatures (450–800 °C). In this communication, we report on the use of Raman spectroscopy to study effect of composition and sintering temperature on the resulting material. The phase evolutions in LiAlxCo1−xO2 compositions were studied using micro-Raman spectroscopy and a phase diagram is proposed based on the observations. For less Al content, the low-temperature phases of LiAlxCo1−xO2 showed Raman spectra corresponding to a monoclinic (space group C2/m) structure, while a low-temperature spinel (space group Fd3m) phase was observed for 50% or more Al in these compounds. All these compositions exhibited a layered hexagonal (space group R3m) structure when sintered above 700 °C. Raman spectra also revealed residual Co3O4 in the low-temperature forms of LiCoO2 and LiA10.01Co0.9O2.

scholarly journals Effect of the Analytic Regions on the Quality Trend of Diamond-like/Graphitic Carbon Ratios in Raman Spectra

2010 ◽  
Vol 65 (1) ◽  
pp. 67-71 ◽  
Author(s):  
Ai-Lin Shen ◽  
Yu-Ching Weng ◽  
Tse-Chuan Chou
Keyword(s):  
Raman Spectroscopy ◽  
Boundary Conditions ◽  
Raman Spectra ◽  
Integral Intensity ◽  
Integral Boundary Conditions ◽  
Peak Height ◽  
Graphitic Carbon ◽  
Peak Height Ratio ◽  
Integral Boundary ◽  
Data Set

Raman spectroscopy is a useful and non-destructive tool for the structural characterization of diamond-like carbon (DLC) films. Even though Raman spectroscopy is not a quantitative technique, the area integral intensity ratio of D and G peaks (ID/IG) derived by the fitting of separate Gaussian curves usually serves as an indicator of the quality trend of diamond-like material. However, conflicting reports still exist on the diamond-like films analyzed by the fitting method of Raman spectra. In this work we show that the quality trend of the diamond-like/graphitic carbon ratio is critically dependent upon the boundary conditions of the analytic regions. We also examine the possibility of directly applying the peak height ratio HD/HG as an alternative method to analyze Raman spectra. The method based on peak height ratios (HD/HG), and an established method using ID/IG ratios can give similar results depending on the choice, in the latter method, of the boundary conditions used for integration. However, the method based on the determination of peak heights avoids the arbitrary assignment of integral boundary conditions while additionally generating a data set that shows statistically smaller standard deviations than the commonly used integration method

The dependence of thymine and thymidine Raman spectra on solvent

2004 ◽  
Vol 82 (6) ◽  
pp. 1092-1101 ◽  
Author(s):  
L Beyere ◽  
P Arboleda ◽  
V Monga ◽  
G R Loppnow
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Raman Spectra ◽  
Vibrational Modes ◽  
Frequency Shifts ◽  
Hydrogen Bonding Interactions ◽  
Lone Pairs ◽  
Vibrational Bands ◽  
Donor Numbers ◽  
Solvent Molecules

Recent work has focused on developing Raman spectroscopy as a noninvasive probe of DNA interactions with solvents, intercalants, proteins, and other ligands. Here, we report the Raman spectra of thymine in eight solvents and thymidine in nine solvents obtained with visible excitation. Raman spectra under acidic, neutral, and basic conditions were also obtained of both thymine and thymidine. Changes in both the frequencies and intensities of several of the vibrational bands in the 800–1800 cm–1 region are observed. No evidence of deprotonation in the different solvents is observed for either thymine or thymidine. Correlations of the observed frequency shifts of specific vibrational modes with characteristic properties of the solvent for both thymine and thymidine show a significant correlation with acceptor and donor numbers, measures of the hydrogen-bonding ability of the solvent, in both thymine and thymidine. These results are interpreted in terms of hydrogen-bonding interactions between the N-H protons of the thymine base and lone pairs of electrons on the solvent molecules and between the solvent hydrogens and lone pairs on C=O sites. The solvent-dependent intensity in vibrational bands of thymine between 1500 and 1800 cm–1 indicates a strong interaction between thymine and solvent at the C=O and N-H sites that leads to separation of the C=O stretches from the C=C stretch. The intensity variations with solvent were much smaller for thymidine than for thymine, perhaps as a result of replacing the N1 proton by the sugar. These results suggest that Raman spectroscopy is uniquely sensitive to specific interactions of thymine and thymidine with their environment.Key words: Raman spectroscopy, thymine, thymidine, solvent effects, hydrogen bonding.

Sign in / Sign up

Export Citation Format

Share Document