Collective vibrational modes in biological molecules investigated by terahertz time-domain spectroscopy

Authors

  • M. Walther,

    1. Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
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  • P. Plochocka,

    1. Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw, Poland
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  • B. Fischer,

    1. Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
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  • H. Helm,

    Corresponding author
    1. Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
    • Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
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  • P. Uhd Jepsen

    Corresponding author
    1. Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
    • Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
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Abstract

We present well-resolved absorption spectra of biological molecules in the far-IR (FIR) spectral region recorded by terahertz time-domain spectroscopy (THz-TDS). As an illustrative example we discuss the absorption spectra of benzoic acid, its monosubstitutes salicylic acid (2-hydroxy-benzoic acid), 3- and 4-hydroxybenzoic acid, and aspirin (acetylsalicylic acid) in the spectral region between 18 and 150 cm−1. The spectra exhibit distinct features originating from low-frequency vibrational modes caused by intra- or intermolecular collective motion and lattice modes. Due to the collective origin of the observed modes the absorption spectra are highly sensitive to the overall structure and configuration of the molecules, as well as their environment. The THz-TDS procedure can provide a direct fingerprint of the molecular structure or conformational state of a compound. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 310–313, 2002

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