Terahertz tyrosine modes

We have measured the terahertz spectrum of pure L-tyrosine at nineteen temperatures in the range 6 K to 300 K using a synchrotron as the source of radiation. By fitting the temperature dependence of the observed modes with a Bose–Einstein model, we determine unequivocal low-frequency modes of L-tyrosine at absolute zero temperature occur at 1.02 ± 0.01, 1.61 ± 0.01, 1.97 ± 0.01, and 2.19 ± 0.01 THz. This determination is consistent with the more reliable of the earlier measurements. We conclude that many of the recently reported features in the terahertz spectrum of L-tyrosine are experimental artefacts.