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Terahertz Spectroscopy and Density Functional Theory Calculations of dl-Norleucine and dl-Methionine.

Jens NeuHeinrich NikonowCharles A Schmuttenmaer
Published in: The journal of physical chemistry. A (2018)
We present terahertz (THz) measurements and density functional theory (DFT) calculations of two amino acid crystals: dl-norleucine and dl-methionine. Their molecular structures are very similar and therefore also their crystal structures. We report the absorption spectra for both amino acids, which have a strong resonance at 1.87 THz in dl-norleucine and 1.94 THz in dl-methionine. In addition, we find a higher frequency resonance at 2.49 THz in dl-methionine, which has no corresponding mode in dl-norleucine. The experimental data are supported by DFT calculations, which show that the origin of the two strongest vibrational modes in dl-norleucine and dl-methionine are based on the same underlying vibrational motions, whereas the 2.49 THz resonance in dl-methionine is due to the motion of the sulfur atom, which is not present in dl-norleucine.
Keyphrases
  • density functional theory
  • molecular dynamics
  • amino acid
  • molecular dynamics simulations
  • energy transfer
  • high resolution
  • single molecule
  • electronic health record
  • quantum dots