Formation of xenon-nitrogen compounds at high pressure

Abstract

Molecular nitrogen exhibits one of the strongest known interatomic bonds, while xenon possesses a closed-shell electronic structure: a direct consequence of which renders both chemically unreactive. Through a series of optical spectroscopy and x-ray diffraction experiments, we demonstrate the formation of a novel van der Waals compound formed from binary Xe-N2 mixtures at pressures as low as 5 GPa. At 300 K and 5 GPa Xe(N2)2-I is synthesised, and if further compressed, undergoes a transition to a tetragonal Xe(N2)2-II phase at 14 GPa; this phase appears to be unexpectedly stable at least up to 180 GPa even after heating to above 2000 K. Raman spectroscopy measurements indicate a distinct weakening of the intramolecular bond of the nitrogen molecule above 60 GPa, while transmission measurements in the visible and mid-infrared regime suggest the metallisation of the compound at ~100 GPa.

High pressure synthesis and stability of cobalt hydrides

“…20,21 Loading of hydrogen was confirmed by the observation of the hydrogen vibrational mode using a custom-built micro-focused Raman system. 22,23 Rhenium gaskets were used to form the sample chamber in all experimental runs, diamond anvil culets ranged from 200 -250 µm, with sample sizes ranging between 50 to 125 µm once hydrogen was in the solid state.…”

Electrostatic force driven helium insertion into ammonia and water crystals under pressure

“…Although hundreds of NG compounds 2,3 have been synthesized, stable solid compounds of He have been discovered only very recently 4 . Application of high pressure is one of the effective methods for preparing NG compounds 3,[5][6][7][8] . High pressures can change the relative energy ordering of atomic orbitals and can promote new oxidation states of elements.…”

Reactivity of Hydrogen-Helium and Hydrogen-Nitrogen Mixtures at High Pressures

“…Through this combined study, we can demonstrate that the recently claimed chemical association of H 2 -He can be attributed to significant N 2 contamination and subsequent formation of N 2 -H 2 compounds.Understanding the behaviour of molecular mixtures under pressure is of a great importance to many scientific fields varying from chemistry to the studies of internal structures of astronomical bodies [1, 3]. A wide range of phenomena have been observed in high-pressure molecular-mixtures such as phase separation, co-crystallisation, host-guest structures and chemical reaction [4][5][6][7]. Since the discovery of solid van der Waals compounds in the highpressure helium-nitrogen system [8], binary mixtures of elemental gasses have attracted much attention.…”

“…We have extensive experience in producing gas mixtures and great care needs to be taken to ensure that the ballast volume between gas bottles in the mixture setup is adequately purged with the consituent gases. [33,44] We have sometimes observed trace nitrogen contamination from air due to this, however in these cases we would disregard the contaminated gas bottle. In this study, we obtain our mixtures commercially with guaranteed levels of purity.…”