Interactions in the ammonia-deuterium system under pressure

18th APS-SCCM; 24th AIRAPT

Borstad, G.M.^1,3 ; Yoo, C.S.^2,3

Department of Physics and Astronomy, Washington State University, Pullman

WA

99164, United States^1

Department of Chemistry, Washington State University, Pullman

WA

99164, United States^2

Institute for Shock Physics, Washington State University, Pullman

WA

99164, United States^3

关键词: Frequency shift;    Function of pressure;    Hydrogen isotope;    Hydrogen molecule;    Micro Raman Spectroscopy;    Proton exchange;    Repulsive interactions;    Vibration modes;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/500/3/032002/pdf
DOI  :  10.1088/1742-6596/500/3/032002

来源: IOP

【 摘 要 】

We have investigated the NH3-D2mixture to 50 GPa using micro-Raman spectroscopy. Proton exchange was observed in the mixture, resulting in the formation of deuterated isotopes of ammonia and the formation of HD and H2. We report the changes in the vibrational spectra of the various components of the mixture, which include blueshifts and splitting in the vibration modes of hydrogen. These frequency shifts in the mixture are compared to frequency shifts in mixtures composed of the hydrogen isotopes. The changes not accounted for by interactions between the hydrogen molecules suggest repulsive interactions between the hydrogen and ammonia. The bond length of the hydrogen molecules is calculated using a Morse potential, revealing a bond length shorter than in pure hydrogen. Additionally, a change in slope of the bond length as a function of pressure was observed around ∼10-18 GPa, which is attributed to the reordering Phase IV to V transition in ammonia.