Infrared Spectroscopy in Liquid Hydrogen Isotopologues for the ISS of ITER

Isotopic Effects on Intermolecular and Intramolecular Structure and Dynamics in Hydrogen, Deuterium, and Tritium Liquids: Normal Liquid and Weakly and Strongly Cooled Liquids

“…The bond frequencies were estimated from the peak frequencies of the power spectra obtained by a Fourier transformation of the time-dependent bond length (see Figure S8). We note that the current bond frequencies of H 2 , D 2 , and T 2 overestimate the experimental vibrational frequencies by approximately 11% that would not significantly affect other important properties such as RDFs and diffusion coefficients reported here. ,, …”

“…Differences in thermodynamic properties such as phase-transition temperature and transport coefficients among liquids of the different isotopic compositions should be ascribed to their pronounced NQEs in the order of H 2 , D 2 , and T 2 as well as the mass difference rather than to any subtle difference in the electronic interaction potentials. , Static and dynamical structure factors as well as coefficients of self-diffusion in liquid deuterium have been measured by neutron diffraction experiments. ,− Those experimental results confirmed inadequacy of classical description of nuclei and required treating nuclei quantum mechanically taking into account the NQEs …”

“…We note that the current bond frequencies of H 2 , D 2 , and T 2 overestimate the experimental vibrational frequencies by approximately 11% that would not significantly affect other important properties such as RDFs and diffusion coefficients reported here. 22,24,44 Figure 7a−c shows the extent of nuclear delocalization depending on the isotopes as distributions of the NWP width. The distributions become sharper as the temperature decreased from 25 K down to 5 K, reflecting the poorer thermal modulations at the lower temperature.…”

“…3,14−21 Those experimental results confirmed inadequacy of classical description of nuclei and required treating nuclei quantum mechanically taking into account the NQEs. 22 Several quantum mechanical approaches have been employed to elucidate the anomalous tendency observed in the quantum liquids. Semiquantum methods suitable for numerical simulations of p-H 2 and o-D 2 ensembles have been proposed based on the imaginary-time path-integral theory.…”