TY - JOUR
T1 - Chemically Assisted Precompression of Hydrogen Molecules in Alkaline-Earth Tetrahydrides
AU - Pena Alvarez, Miriam
AU - Binns, Jack
AU - Marques , Miriam
AU - Kuzovnikov, Mikhail
AU - Dalladay-Simpson, Philip
AU - Pickard, Chris J
AU - Ackland, Graeme J.
AU - Gregoryanz, Eugene
AU - Howie, Ross T.
N1 - Funding Information:
Dr. Peña-Alvarez acknowledges the support of the UKRI Future Leaders Fellowship Mrc-Mr/T043733/1. We want to thank Dr. McMahon for lending us the glovebox of his laboratory to prepare the samples and Dr. Kelsall for his assistance during the sample loadings. We also thank Dr. Ranieri for his assistance during experiments. Dr. Peña-Alvarez, Dr. Marqués, Dr. Gregoryanz, and Prof. Ackland would like to acknowledge the support of the European Research Council (ERC) Grant “Hecate”, Reference No. 695527. Dr. Howie acknowledges that the project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 948895 “MetElOne”). Part of this work was supported by the National Science Foundation of China (Grant No. 11974034). Portions of this work were performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation, Earth Sciences (EAR-1634415), and the U.S. Department of Energy, GeoSciences (DE-FG02-94ER14466, DE-AC02-06CH11357.). We thank Dr. Prakapenka and Dr. Chariton for their experimental assistance in experiments 216253. We acknowledge DESY (Hamburg, German), a Helmholtz Association HGF as parts of this research were carried out at PETRA-III, and we would like to thank Dr. Liermann, Dr. Husband, and Dr. Glazyrin for assistance in using beamline P02.2 (I-20191508 EC, I-20191366, I-20190519 EC, I-20190248 EC, I-20181128, I-20181075 EC). The authors acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities at the ID15B beamline under proposals HC-3934 and HC-4221. In particular, the authors acknowledge Dr. Hanfland for his assistance during experiments. Computational resources provided by UK Materials and Molecular Modelling Hub partially funded by EPSRC (EP/P020194/1 and EP/T022213/1) and the UKCP consortium under the EPSRC grant (EP/P022561/1).
Publisher Copyright:
© 2022 The Authors. Published by American Chemical Society.
PY - 2022/9/15
Y1 - 2022/9/15
N2 - Through a series of high pressure diamond anvil experiments, we report the synthesis of alkaline earth (Ca, Sr, Ba) tetrahydrides, and investigate their properties through Raman spectroscopy, X-ray diffraction, and density functional theory calculations. The tetrahydrides incorporate both atomic and quasi-molecular hydrogen, and we find that the frequency of the intramolecular stretching mode of the H훿−2 units downshifts from Ca to Sr and to Ba upon compression. The experimental results indicate that the larger the host cation, the longer the H훿−2 bond. Analysis of the electron localization function (ELF) demonstrates that the lengthening of the H–H bond is caused by the charge transfer from the metal to H훿−2 and by the steric effect of the metal host on the H–H bond. This effect is most prominent for BaH4, where the precompression of H훿−2 units at 50 GPa results in bond lengths comparable to that of pure H2 above 275 GPa
AB - Through a series of high pressure diamond anvil experiments, we report the synthesis of alkaline earth (Ca, Sr, Ba) tetrahydrides, and investigate their properties through Raman spectroscopy, X-ray diffraction, and density functional theory calculations. The tetrahydrides incorporate both atomic and quasi-molecular hydrogen, and we find that the frequency of the intramolecular stretching mode of the H훿−2 units downshifts from Ca to Sr and to Ba upon compression. The experimental results indicate that the larger the host cation, the longer the H훿−2 bond. Analysis of the electron localization function (ELF) demonstrates that the lengthening of the H–H bond is caused by the charge transfer from the metal to H훿−2 and by the steric effect of the metal host on the H–H bond. This effect is most prominent for BaH4, where the precompression of H훿−2 units at 50 GPa results in bond lengths comparable to that of pure H2 above 275 GPa
U2 - 10.1021/acs.jpclett.2c02157
DO - 10.1021/acs.jpclett.2c02157
M3 - Letter
C2 - 36053162
SN - 1948-7185
VL - 13
SP - 8447
EP - 8454
JO - The Journal of Physical Chemistry Letters
JF - The Journal of Physical Chemistry Letters
IS - 36
M1 - 13
ER -