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

Determination of Methamphetamine and its Related Compounds Using Fourier Transform Raman Spectroscopy

1997 ◽  
Vol 51 (12) ◽  
pp. 1796-1799 ◽  
Author(s):  
Hitoshi Tsuchihashi ◽  
Munehiro Katagi ◽  
Mayumi Nishikawa ◽  
Michiaki Tatsuno ◽  
Hiroshi Nishioka ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Ephedrine Hydrochloride ◽  
Fourier Transform Raman Spectroscopy ◽  
Plastic Bag ◽  
Amphetamine Sulfate ◽  
Fourier Transform Raman ◽  
Related Compounds ◽  
Ft Raman

Fourier transform Raman spectroscopy (FT-Raman) is investigated as a simple and rapid method for the determination of the abused drug methamphetamine and its related compounds. Compounds can be reliably identified by using measurements made nondestructively and without the need for any sample preparation in around 1 min. The Raman spectrum of methamphetamine hydrochloride (MA) shows clear differences in spectra from a range of its related compounds such as amphetamine sulfate and ephedrine hydrochloride. These differences are adequate for spectral differentiation of the compounds. With the use of the FT-Raman technique, MA is also reliably identifiable to a detection limit of 1% (w/w) diluted in sodium chloride or water. FT-Raman spectra of MA were recorded through plastic packaging (polyethylene or polypropylene bags) typical of that used either by criminals for transportation or by law enforcement for containing and sealing evidence. Measurements could be made directly without removing the drug from the bag; excellent-quality spectra could be obtained with very little perturbation by the plastic bag.

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.

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.

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