@article {520, title = {Phonon Kinetics of Fructose at the Melting Transition}, journal = {J. Phys. Chem. C}, volume = {125}, year = {2021}, pages = {12269-12276}, chapter = {12269}, abstract = {

Terahertz time domain spectroscopy (THz TDS) is used to measure the melting kinetics of fructose molecular crystals. Combining single-crystal anisotropy measurements with density functional calculations, we assign the phonon frequencies and interrogate how specific phonons behave with melting. While nearly all the low-frequency phonons continuously red-shift with heating and melting, the lowest-energy phonon polarized along the c-axis blue-shifts at the melting temperature, suggesting an initial structural change immediately before melting. We find that the kinetics follow a 3D growth model with large activation energies, consistent with previous differential scanning calorimetry (DSC) measurements. The large activation energies indicate that multiple H-bonds must break collectively for the transition. The results suggest the generality of the kinetics for molecular crystals and that THz TDS with picosecond resolution could be used to measure ultrafast kinetics.

}, doi = {10.1021/acs.jpcc.1c00610}, author = {A. Davie and F. Vandrevala and S. Dampf and Y. Deng and D. K. George and E. D. Sylvester and T. Korter and E. Einarsson and J. B. Benedict and A. G. Markelz} } @proceedings {299, title = {Angular Distortion Removal of THz Anisotropic Dichroism Microscope}, year = {2019}, month = {2019}, pages = {1 - 2}, address = {Paris, France}, abstract = {

We have developed a stationary sample THz anisotropic dichroism microscope as a powerful tool for material characterization. The key innovation is the use of an iso-response curve defined by the terahertz and detection light polarizations. Here we show that following a continuous iso-response curve introduces angular distortion in the spectrum, and this distortion can be eliminated by using a discontinuous iso-response angle pairs avoiding large gradient regions. Employing this additional constraint on the relative polarizations provides a convenient technique for rapid anisotropic terahertz spectroscopy.

}, keywords = {absorption, angular distortion removal, Biomedical measurement, continuous iso-response curve, detection light polarizations, discontinuous iso-response angle pairs, Distortion, light polarisation, material characterization, Microscopy, proteins, rapid anisotropic terahertz spectroscopy, relative polarizations, spectroscopy, stationary sample, terahertz spectroscopy, terahertz wave spectra, THz anisotropic dichroism microscope, vibrations}, isbn = {2162-2035}, doi = {10.1109/IRMMW-THz.2019.8873793}, url = {https://ieeexplore.ieee.org/document/8873793}, author = {Y. Deng and K. Niessen and A. Markelz} }