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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.19: Poster

Freitag, 12. März 2004, 10:30–13:00, B

Far-infrared spectroscopy of α amino acids — •Adriana Matei, Natalia Drichko, Bruno Gompf, and Martin Dressel — 1.Physikalisches Institut, Universität Stuttgart

In contrast to covalent bonds, which leads to intramolecular vibrations in mid-infrared, low energy interactions such as hydrogen bonds and van der Waals forces can lead to intermolecular vibrations in far-infrared (THz-range).

We report on FTIR measurements of a large number of amino acids prepared as pellets in a polyethylene matrix in the region 50-650 cm⁻¹. The observed absorption peaks can be related to five regions: the region around 600 cm⁻¹ (CO₂ wagging), around 540 cm⁻¹ (NH₃ torsion and CO₂ rocking/wagging/bending), the one at 320 cm⁻¹ (CC^α N deformation), and the one at 200 cm⁻¹ (CO₂ torsion and CC^α N deformation). The features between 50 and 200 cm⁻¹ are intermolecular vibrations due to hydrogen bonds. Starting from previous normal mode calculations, an assignment of the observed vibration frequencies is possible.