title: Collective vibrational modes in biological molecules investigated by terahertz time-domain spectroscopy.
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.
authors.affiliation: Department of Molecular and Optical Physics, Fakultät für Physik, Albert-Ludwigs Universität Freiburg, Stefan-Meier-Strasse 19, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Walther
authors.forename: P
authors.initials: P
authors.lastname: Plochocka
authors.forename: B
authors.initials: B
authors.lastname: Fischer
authors.forename: H
authors.initials: H
authors.lastname: Helm
authors.forename: P
authors.initials: P
authors.lastname: Uhd Jepsen
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D001241:Aspirin / Q000737:chemistry; D019817:Benzoic Acid / Q000737:chemistry; D062385:Hydroxybenzoates / Q000737:chemistry; D010226:Parabens / Q000737:chemistry; D011487:Protein Conformation; D020156:Salicylic Acid / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods*; D013696:Temperature; D013997:Time Factors
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D062385:Hydroxybenzoates; D010226:Parabens; C032948:3-hydroxybenzoic acid; D019817:Benzoic Acid; D020156:Salicylic Acid; D001241:Aspirin