2025/08/09 by Prisk, Timothy R., Hanna, Scott, Azuah, Richard T.
#diffusion #hydrogen #neutron scattering #quantum fluids #tritium
paper · doi:10.13016/oja0-qlxt
We present a quasi-elastic neutron scattering study of liquid deuterium hydride carried out using the Disk Chopper Spectrometer at the National Institute of Standards and Technology. Under saturated vapor pressure, the self-diffusion constant of deuterium hydride obeys an Arrhenius law D = D<sub>0</sub>exp−E<sub>A</sub>/k<sub>B</sub>T, where the prefactor <i>D<sub>0</sub> </i>is given by D<sub>0 </sub>= 9.5±1.2 Å<sup>2</sup>/ps and the activation energy is given by <i>E</i><sub><i>A</i></sub> = 58 ± 2 K. We apply the quantum law of corresponding states to the known diffusion constants of the hydrogen isotopologues. From this application, we estimate that D<sub>0</sub> ≈ 9.1 Å<sup>2</sup>/ps and <i>E</i><sub><i>A</i></sub> ≈ 75 K in liquid tritium. Young’s theory of quantum-mechanical effects in van der Waals fluids [Young, Phys. Rev. A <b>23</b>, 1498 (1981)] is shown to apply to the diffusion constants of the liquid hydrogens. Our results underscore the importance of nuclear quantum effects in shaping the properties and behavior of the hydrogen isotopologues.