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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for global mobility in the premelting of a polynucleotide from temperature-dependent Raman optical activity (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 107-111 
    Details
    ISSN: 1075-4261
    Keywords: conformational mobility ; nucleic acid dynamics ; Raman optical activity ; RNA ; temperature dependence ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The backscattered Raman and Raman optical activity (ROA) spectra of poly(rA)-poly(rU) at 20°C and 45°C in buffered aqueous solution between 650 and 1750 cm-1 are reported. Although the intensity of the majority of the Raman bands increase by varying amounts as the temperature is raised in accordance with the well-known hypochromic effect, the reverse effect is found for the ROA signals which we attribute to thermal accessibility of a greater number of distinct conformations leading to cancellation of ROA signals. The difference ROA spectrum obtained by subtracting the spectrum recorded at 45°C from that recorded at 20°C displays a very similar sign pattern to those at both 20°C and 45°C throughout the spectral region examined. This indicates that the same average structure is maintained in this temperature range and that the thermal fluctuations are correlated through the bases, the glycosidic link, the sugar ring, and the phosphate backbone of both strands. These results indicate that ROA may be a useful new probe of the dynamics of nucleic acid in solution. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 107-111, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Instrument for natural and magnetic Raman optical activity studies in right-angle scattering (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 443-451 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple computer-controlled instrument for natural and magnetic incident circular polarization Raman optical activity (ICP ROA) measurements in right-angle scattering is described. The key spectral elements consist of a fast single-stage monochromator equipped with a holographic notch filter, a highly efficient holographic diffraction grating and a thinned back-illuminated, thermoelectrically cooled charge-coupled device (CCD) detector. A temperature-stabilized longitudinal electro-optic modulator is employed to switch between orthogonal circular polarization states in the incident laser radiation. A polaroid film together with a mica half-wave retardation plate are used to select particular linear polarization states in the Raman scattered radiation with the same instrumental response. High-quality depolarized and polarized Stokes and depolarized anti-Stokes ICP ROA spectra of (R)-(-) and (S)-(+)-phenyloxirane and depolarized magnetic resonance ICP ROA spectra of copper(II) tetrabromide are presented as typical examples of the excellent performane characteristics.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250250703
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  • 3
    Electronic Resource
    Electronic Resource
    On the non-zero depolarization ratio in totally symmetric modes of molecules with cubic point group symmetry (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 473-475 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Imperfections in the incident laser beam polarization modulation technique in linear polarization Raman measurements are calculated on the basis of the Stokes-Mueller formalism. An equation for the depolarization ratio in totally symmetric Raman bands of molecules with cubic point group symmetry is derived, yielding a depolarization ratio of ρ′obs. = 1.38 × 10-3 for the ν1 C—Cl stretching vibration in the C35Cl4 species. The comparison of the computed depolarization ratio with the smallest experimental value reported so far, ρobs. = 2.30 × 10-3, implies that recent attempts to explain the observation of a non-zero depolarization ratio for the ν1 mode in liquid CCl4 by intermolecular interactions present in the condensed phase are less relevant than suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250220809
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  • 4
    Electronic Resource
    Electronic Resource
    Low-wavenumber vibrational Raman optical activity of carbohydrates (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 633-635 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A high optical density holographic notch filter in combination with a single-grating spectrograph was used to increase the spectral range for backscattered Raman optical activity (ROA) measurements of biological molecules in aqueous solution towards lower wavenumber. ROA spectra of D-galactose, D-maltose and laminarin starting at ca. 350 cm-1 are presented as first examples. An ROA couplet observed at 427 ± 10 cm-1 in the spectra of D-maltose, D-cellobiose and laminarin appears to reflect the configuration of glycosidic links in di- and poly-saccharides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250240913
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  • 5
    Electronic Resource
    Electronic Resource
    Polysaccharide vibrational Raman optical activity: Laminarin and pullulan (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 1071-1074 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The backscattered Raman optical activity (ROA) spectra of the β(1-3)-linked polysaccharide laminarin, and its dimer repeating unit D-laminarihiose, together with those of the predominantly α(l-4)-linked polysaccharide pullulan, and its trimer repeating unit D-maltotriose, between 350 and 1500 cm-1 in aqueous solution are reported and discussed. Several differences are evident between the ROA spectra of laminarin and D-laminaribiose which are ascribed to triple helix formation in the polysaccharide. In particular, the signs of four ROA signals between ca. 1050 and 1150 cm-1 are reversed and two ROA signals assigned to vibrations involving the glycosidic link observed at ca. 445 and 1431 cm-1 change sign and increase in intensity, respectively. In contrast, pullulan, which adopts a random coil-type structure in aqueous solution, generates an ROA spectrum that closely resembles that of D-maltotriose.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250261209
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of enantiomeric excess using Raman optical activityThis paper is dedicated to Professor D. A. Long on the occasion of his 70th birthday. (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 727-732 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple method for the determination of enantiomeric excess is described. It is based on depolarized Raman optical activity (ROA) measurements in right-angle scattering employing the incident ciruclar polarization (ICP) modulation approach. The accuracy of this method was assessed utilizing α-pinene as a chiral test compound. The four α-pinene ICP ROA signals associated with the Raman bands observed at ca. 772, 787, 887 and 929 cm-1 were selected to establish a linear relationship between ROA signal strength and enantiomeric composition for a set of calibration mixtures containing both α-pinene enantiomers. Using this relationship, a (+)-α-pinene sample content of 16.3% was determined for a blind mixture containing 83.6% (1S)-(  -  )-α-pinene and 16.4% (1R)-(+)-α-pinene. Similary, utilizing additional spectral subtraction procedures, a (+)-α-pinene sample content of 1.5% was estimated for a test mixture consisting of 50.1% (1S)-(  -  )-α-pinene and 49.9% (1S)-(  -  )-trans-pinane.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250260820
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