01661nas a2200229 4500008004100000245005800041210005800099300001600157490000800173520102600181100001401207700001901221700001401240700001301254700001901267700002201286700001501308700001801323700002101341700002001362856004901382 2021 eng d00aPhonon Kinetics of Fructose at the Melting Transition0 aPhonon Kinetics of Fructose at the Melting Transition a12269-122760 v1253 a

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.

 

1 aDavie, A.1 aVandrevala, F.1 aDampf, S.1 aDeng, Y.1 aGeorge, D., K.1 aSylvester, E., D.1 aKorter, T.1 aEinarsson, E.1 aBenedict, J., B.1 aMarkelz, A., G. uhttps://markelz.physics.buffalo.edu/node/520