The structure of the kaolinite minerals — a FT-Raman study

Clay Minerals ◽  
1997 ◽  
Vol 32 (1) ◽  
pp. 65-77 ◽  
Author(s):  
R. L. Frost
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Near Infrared ◽  
Hydroxyl Groups ◽  
Kaolinite Clay ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Raman Spectroscopy ◽  
The Fourier Transform ◽  
Fourier Transform Raman ◽  
Ft Raman

AbstractThe Fourier transform Raman spectra of the kaolinite minerals have been measured in the 50–3800 cm−1 region using near infrared spectroscopy. Kaolinites are characterized by remarkably intense bands in the 120–145 cm−1 region. These bands, attributed to the O-Si-O and O-Al-O symmetric bending modes, are both polymorph and orientation dependent. The 200–1200 cm−1 spectral range is a finger-print region for clay minerals and each kaolinite clay has its own characteristic spectrum. The structure of clays is fundamentally determined by the position of hydroxyl groups. Fourier-transform Raman spectroscopy readily enables the hydroxyl stretching region to be examined allowing identification of the component bands. The advantages of FT-Raman spectroscopy are shown to enhance the study of the kaolinite structure.

FT-Raman Spectroscopy at 1.339 Micrometers

1994 ◽  
Vol 48 (6) ◽  
pp. 699-701 ◽  
Author(s):  
Kelly J. Asselin ◽  
Bruce Chase
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Near Infrared ◽  
Copper Phthalocyanine ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Raman Spectroscopy ◽  
Anti Stokes ◽  
Fourier Transform Raman ◽  
Ft Raman

The usual laser employed for Fourier transform Raman spectroscopy is a Nd:YAG unit lasing at 1.064 μm. In this work, use of the 1.339-μm lasing emission from Nd:YAG has been demonstrated. The sensitivity of this instrument is comparable to that of conventional FT-Raman instruments, and excellent anti-Stokes spectra can be easily obtained. Operation further into the near-infrared offers additional possibilities for fluorescence minimization. Results are shown for copper phthalocyanine.

Fourier Transform Raman Spectroscopy of Long-Chain Molecules Containing Strongly Absorbing Chromophores

1987 ◽  
Vol 41 (5) ◽  
pp. 721-726 ◽  
Author(s):  
C. G. Zimba ◽  
V. M. Hallmark ◽  
J. D. Swalen ◽  
J. F. Rabolt
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Near Infrared ◽  
Visible Region ◽  
Excitation Spectra ◽  
Chain Molecules ◽  
Scattering Geometry ◽  
Fourier Transform Raman Spectroscopy ◽  
Fourier Transform Raman ◽  
Ft Raman

Fourier transform Raman spectroscopy shows considerable promise as a new characterization technique for molecules which contain chromophores which absorb in the visible region, the region where conventional Raman measurements are made. With the use of near-infrared excitation, spectra in the absence of fluorescence and resonance enhancement are obtained. These advantages can be further enhanced if the collection of data using this technique becomes routine, requiring a level of complexity comparable to that of conventional Raman scattering. Toward that end, the implementation of a 90° scattering geometry in our FT-Raman measurements was undertaken, and the results are shown to be at least comparable to those obtained with the use of reflective optics in a 180° geometry. A number of results on both liquids and solids have also been obtained in order to compare FT-Raman with conventional scanning Raman measurements.

Applications of Fourier Transform Raman Spectroscopy in an Industrial Laboratory

1989 ◽  
Vol 43 (3) ◽  
pp. 516-522 ◽  
Author(s):  
F. J. Bergin ◽  
H. F. Shurvell
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Near Infrared ◽  
Laser Raman Spectroscopy ◽  
Analytical Technique ◽  
Laser Raman ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Raman Spectroscopy ◽  
Ft Ir ◽  
Fourier Transform Raman

In the past, the usefulness of laser Raman spectroscopy as an analytical technique in industrial laboratories has been greatly reduced by problems of laser-induced fluorescence. One method of circumventing this problem is to use near-infrared excitation coupled with a modified FT-IR spectrometer. In this paper, we report the results of some initial exploratory experiments which indicate that significant fluorescence rejection can be achieved. This fluorescence rejection opens up new areas of application for Raman spectroscopy. The advantages and limitations of FT-Raman spectroscopy are discussed. In addition, some initial experiments are outlined on Fourier transform Raman microscopy using a conventional microscope.

Development of Near-Infrared Fourier Transform Raman Spectroscopy for the Study of Biologically Active Macromolecules

1988 ◽  
Vol 42 (7) ◽  
pp. 1188-1193 ◽  
Author(s):  
E. Neil Lewis ◽  
V. F. Kalasinsky ◽  
Ira W. Levin
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Lipid Bilayers ◽  
Near Infrared ◽  
Optical Design ◽  
Membrane Lipid ◽  
Biologically Active ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Raman Spectroscopy ◽  
Ft Raman

General advantages and potential limitations of Fourier transform (FT) Raman spectroscopy using Nd:YAG laser excitation at 1064 nm have been considered for both routine analysis and specific biophysical applications. Optical design and operating parameters which affect the quality and reproducibility of the data are discussed. Moderately high resolution spectra (0.25 cm−1) of liquids are obtained with relative ease, and the results are compared with dispersive spectra. Particular emphasis has been placed on applications to biological systems where intrinsic fluorescence has traditionally limited the use of dispersive Raman spectroscopy. As an example of a biophysical study, we demonstrate the utility of FT-Raman spectroscopy in elucidating the interactions of polyene antibiotics with model membrane lipid bilayers as a means of understanding novel drug/membrane interactions at the molecular level.

Structural Analysis of Triacylglycerols and Edible Oils by Near-Infrared Fourier Transform Raman Spectroscopy

2003 ◽  
Vol 57 (4) ◽  
pp. 413-418 ◽  
Author(s):  
Yih-Ming Weng ◽  
Ru-Hui Weng ◽  
Chin-Yin Tzeng ◽  
Wenlung Chen
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Structural Analysis ◽  
Near Infrared ◽  
Edible Oils ◽  
Structural Difference ◽  
Raman Intensity ◽  
Fourier Transform Raman Spectroscopy ◽  
Fourier Transform Raman ◽  
Ft Raman

Fourier transform Raman spectroscopy was employed for structural analysis of triacylglycerols and edible oils. Raman spectra sensitively reflected structural changes in oils. Even slight structural fluctuation between triacylglycerols and free fatty acids led to obvious differences in Raman bands as shown by C–O–C stretching from 800 to 1000 cm−1 and the band at 1742 cm−1. Structural difference in geometric isomers was easily distinguished as proved by C = C stretching at 1655 cm−1 ( cis) shifting to 1668 cm−1 ( trans) and by =C–H in-plane bending at 1266 cm−1 in cis disappearing in the trans isomer. Raman intensity at 1266, 1302, and 1655 cm−1 changed concomitantly with the change of double-bond content in oils. It showed that FT-Raman was capable of precisly reflecting the content of double bonds in oils. A linear correlation with high consistency between the Raman intensity ratio ( v1655 /v1444) and the iodine value was obtained for commercial oils. Based on the results, FT-Raman spectroscopy proved itself a simple and rapid technique for oil analysis since each measurement could be directly completed in 3 min without any sample modifications.

Fourier Transform Raman Spectroscopy Using a Bench-Top FT-IR Spectrometer

1988 ◽  
Vol 42 (5) ◽  
pp. 796-800 ◽  
Author(s):  
S. F. Parker ◽  
K. P. J. Williams ◽  
P. J. Hendra ◽  
A. J. Turner
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Near Infrared ◽  
Continuous Wave ◽  
Laser Excitation ◽  
Visible Region ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Ir ◽  
Fourier Transform Raman ◽  
Ft Raman

Fourier transform Raman spectroscopy has been performed with an inexpensive bench-top FT-IR spectrometer optimized for the near-infrared. The laser excitation source was from a continuous-wave Nd: YAG laser with an output at 1.064 μm. Spectra from solid samples, ground as powders, have been obtained. Many of these are well known to fluoresce in the visible region and are thus intrinsically difficult to study by the Raman method. The FT-Raman method is described, and improvements in the technique are considered.

Potential of Near-Infrared Fourier Transform Raman Spectroscopy in Food Analysis

1992 ◽  
Vol 46 (10) ◽  
pp. 1503-1507 ◽  
Author(s):  
Y. Ozaki ◽  
R. Cho ◽  
K. Ikegaya ◽  
S. Muraishi ◽  
K. Kawauchi
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Fatty Acid ◽  
Raman Spectra ◽  
Food Analysis ◽  
Near Infrared ◽  
Egg White ◽  
Ft Raman Spectroscopy ◽  
Ft Raman

The 1064-nm excited Fourier transform (FT) Raman spectra have been measured in situ for various foods in order to investigate the potential of near-infrared (NIR) FT-Raman spectroscopy in food analysis. It is demonstrated here that NIR FT-Raman spectroscopy is a very powerful technique for (1) detecting selectively the trace components in foodstuffs, (2) estimating the degree of unsaturation of fatty acids included in foods, (3) investigating the structure of food components, and (4) monitoring changes in the quality of foods. Carotenoids included in foods give two intense bands near 1530 and 1160 cm−1 via the pre-resonance Raman effect in the NIR FT-Raman spectra, and therefore, the NIR FT-Raman technique can be employed to detect them nondestructively. Foods consisting largely of lipids such as oils, tallow, and butter show bands near 1658 and 1443 cm−1 due to C=C stretching modes of cis unsaturated fatty acid parts and CH2 scissoring modes of saturated fatty acid parts, respectively. It has been found that there is a linear correlation for various kinds of lipid-containing foods between the iodine value (number) and the intensity ratio of two bands at 1658 and 1443 cm−1 ( I1658/ I1443), indicating that the ratio can be used as a practical indicator for estimating the unsaturation level of a wide range of lipid-containing foods. A comparison of the Raman spectra of raw and boiled egg white shows that the amide I band shifts from 1666 to 1677 cm−1 and the intensity of the amide III band at 1275 cm−1 decreases upon boiling. These observations indicate that most α-helix structure changes into unordered structure in the proteins constituting egg white upon boiling. The NIR FT-Raman spectrum of old-leaf (about one year old) Japanese tea has been compared with that of its new leaf. The intensity ratio of two bands at 1529 and 1446 cm−1 ( I1529/ I1446), assignable to carotenoid and proteins, respectively, is considerably smaller in the former than in the latter, indicating that the ratio is useful for monitoring the changes in the quality of Japanese tea.

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