Asynchronous Pulsed-Laser-Excited Fourier Transform Raman Spectroscopy and its Applications

1993 ◽  
Vol 47 (9) ◽  
pp. 1457-1461 ◽  
Author(s):  
Akira Sakamoto ◽  
Yukio Furukawa ◽  
Mitsuo Tasumi ◽  
Koji Masutani
Keyword(s):  
Fourier Transform ◽  
Pulsed Laser ◽  
Probe Laser ◽  
Time Resolved ◽  
Pass Filter ◽  
Pulsed Excitation ◽  
Fourier Transform Raman Spectroscopy ◽  
Gate Circuit ◽  
Fourier Transform Raman ◽  
Ft Raman

An asynchronous pulsed-laser-excited Fourier transform Raman spectrophotometer based on a conventional continuous-scan interferometer has been developed. The additional assembly required for pulsed-laser-excited measurements, which consists of a pulsed Nd:YAG laser, a gate circuit, and a low-pass filter, can be attached to any conventional FT-Raman spectrophotometer. The principle of the signal-processing of this method is almost the same as that of the asynchronous time-resolved Fourier transform infrared spectroscopy reported previously. This method does not require the synchronization between the Raman excitation and the sampling of the A/D converter. As an application of this method, it is demonstrated that the use of a pulsed laser and a gate circuit can give a significant increase in signal-to-noise ratios over continuous-wave measurements with the same average laser power. It is also shown that when a constant background (for example, thermal radiation from samples at high temperatures) or a long-lived background is present, the use of pulsed excitation and a gate circuit can effectively reduce the background. Moreover, pulsed excitation can be used for recording time-resolved Raman spectra by using an FT-Raman spectrophotometer. The time resolution is governed only by the width of the probe laser pulse. The potentiality of this method is demonstrated.

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.

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.

Investigation of Normal and Malignant Tissue Samples from the Human Stomach Using Fourier Transform Raman Spectroscopy

2002 ◽  
Vol 56 (5) ◽  
pp. 570-573 ◽  
Author(s):  
X.-F. Ling ◽  
Y.-Z. Xu ◽  
S.-F. Weng ◽  
W. H. Li ◽  
Xu Zhi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Normal Tissue ◽  
Human Stomach ◽  
Malignant Tissue ◽  
Tissue Samples ◽  
Fourier Transform Raman Spectroscopy ◽  
Spectroscopic Identification ◽  
Fourier Transform Raman ◽  
Ft Raman

Fourier transform (FT) Raman studies of 40 tissue samples from the human stomach, including 22 normal and 18 malignant tissue samples, were performed. These stomach tissue samples had been classified as normal or malignant on the basis of pathological studies and biopsy detection. The results indicate that a series of major bands in the FT-Raman spectrum can be used to distinguish the malignant tissue from the normal tissue. Subtraction spectra support the result of the spectroscopic identification. Statistical analysis is also in agreement with the FT-Raman measurements.

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.

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.

SPECTROSCOPIC AND THERMAL STUDIES OF GEL-GROWN COPPER MALONATE CRYSTALS

2010 ◽  
Vol 24 (11) ◽  
pp. 1135-1143 ◽  
Author(s):  
VARGHESE MATHEW ◽  
JOCHAN JOSEPH ◽  
SABU JACOB ◽  
LIZYMOL XAVIER ◽  
K. E. ABRAHAM
Keyword(s):  
Thermal Decomposition ◽  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Thermal Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fourier Transform Raman Spectroscopy ◽  
Fourier Transform Raman ◽  
Derivative Thermogravimetry ◽  
Ft Raman

Copper malonate crystals were grown using silica gel as the growth medium. The grown crystals were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT Raman). The thermal decomposition of the compound was investigated using thermogravimetry (TG) and derivative thermogravimetry (DTG) measurements.

scholarly journals Picosecond Time-Resolved Fourier Transform Raman Spectroscopy of 9,10-Diphenylanthracene in the Excited Singlet State

1995 ◽  
Vol 49 (5) ◽  
pp. 645-649 ◽  
Author(s):  
Gouri S. Jas ◽  
Chaozhi Wan ◽  
Carey K. Johnson
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Excited State ◽  
Near Infrared ◽  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Time Resolved ◽  
Fourier Transform Raman Spectroscopy ◽  
Fourier Transform Raman

Time-resolved Fourier transform Raman spectroscopy of the highly fluorescent chromophore 9,10-diphenylanthracene (DPA) in cyclohexane and ethanol is described. Raman spectra of the first excited singlet state of DPA were obtained with 100-ps resolution at several time delays between pump pulses at 355 nm and probe pulses at 1064 nm. The near-infrared excited-state Raman scattering is enhanced by resonance with an excited-state transition of DPA. The excited-state Raman bands decay in about 5–6 ns. Evidence for interaction of the solvent with the DPA excited state is observed in the cyclohexane C-H stretching bands.

Observation of Picosecond Transient Raman Spectra by Asynchronous Fourier Transform Raman Spectroscopy

1998 ◽  
Vol 52 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Akira Sakamoto ◽  
Hiromi Okamoto ◽  
Mitsuo Tasumi
Keyword(s):  
Raman Spectroscopy ◽  
Signal Processing ◽  
Fourier Transform ◽  
Raman Spectra ◽  
Light Pulse ◽  
Pulse Width ◽  
Probe Laser ◽  
Fourier Transform Raman Spectroscopy ◽  
Ft Raman Spectroscopy ◽  
Ft Raman

Asynchronous Fourier transform (FT) Raman spectroscopy with 100 picosecond time resolution has been developed. A signal-processing assembly required for time-resolved and transient Raman measurements consists of a picosecond Nd:YLF laser system, a gate circuit, and a low-pass filter, and it can be attached to any conventional continuous-scan FT-Raman spectrophotometer. The principle of signal processing employed in this method is almost the same as that of asynchronous pulsed-laser-excited FT-Raman spectroscopy. This method does not require synchronization between Raman excitation by probe laser pulses and sampling by the analog-to-digital converter. Transient Raman spectra have been obtained from the first excited singlet state of three anthracene derivatives in cyclohexane solutions and photoexcited poly( p-phenylenevinylene) [(C6H4CH=CH) n] by using 351 nm light (pulse width ã 70 ps) for photoexcitation and 1053 nm light (pulse width ã 100 ps) for Raman excitation.

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