Michael G. Pravica¹*, Yonggang Wang³, Melanie White¹, Yuming Xiao², Paul Chow²
*Corresponding author
1. Department of Physics and Astronomy, University of Nevada Las Vegas and
High Pressure Science and Engineering Center (HiPSEC), Las Vegas, USA
2. High Pressure Collaborative Access Team (HP-CAT),
Advanced Photon Source, Argonne National Laboratory, Argonne, USA
3. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Beijing, China

Abstract

We sought to demonstrate that hard x-rays can initiate a sequence of acatalytic photochemical reactions with the aim of creating molecular mixtures (O₂ and F₂) and then observe the two species react to form OF₂ and with little introduction of heat. Two x-ray Raman scattering (XRS) studies of 1. KBF₄ and 2. a mixture of KBF₄ + KClO₄ pressurized to 3 GPa in a diamond anvil cell (DAC) at ambient temperature at the 16 ID-D undulator beamline at the Advanced Photon Source. The spectrometer collected photons with energy losses around 680 eV near the fluorine K-edge. Fluorine K-edge x-ray Raman spectroscopy demonstrated the clear formation of a new peak near 682 eV energy loss after some 8 hours of irradiation and detection of the KBF₄/KClO₄ mixture which likely represents OF₂ produced from the following reaction: O₂+2F₂→ 2OF₂ following irradiation of the mixture to release O₂ and F₂ , respectively, from each constituent.

INTRODUCTION

Fluorine is the most electronegative element, and thus, would be an excellent choice as a reactant to drive novel chemistry under extreme conditions (e.g. inside pressurized diamond anvil cells)(1) for industrial purposes and for fundamental chemical/bonding insights. Understanding how this reactive element interacts with other simple molecular reactants such as O₂ and its mobility under high pressure would be of great interest from the standpoint of better ascertaining the behavior of simple molecular mixtures under shockwave conditions to aid detonation chemistry which occurs at extreme conditions (high pressure and/or high temperature). As there are fluorine-containing explosives (2) which use the NF₂ group as an oxidizing moiety (2, 3) such as 3,3,7,7-tetrakis(difluoramino)octahydro1,5-dinitro-1,5-diazocine (HNFX)(2) and Bis- and Tris-difluoroamino perfluorobutane (3), and as F₂ can react explosively with some molecules (e.g. H₂), significant insights may also be garnered by the effort of developing fluorine chemistry at extreme conditions.

However, to study fluorine at high pressure, i ...