Forcing Cesium into Higher Oxidation States via Useful Hard X-ray Induced Chemistry at Extreme Conditions

Recent theoretical work published in Nature Chemistry postulates the existence of cesium in high oxidation states when bonding with fluorine. It is thus predicted to behave as a p-block element (such as xenon) at pressures above 5 GPa. At these pressures, fluorine atoms may bond with the inner p-shell electrons forming CsFn, where n may vary from 2 up to 6; thus the oxidation state of Cs may change up to 6+. My research focused on physically synthesizing these compounds and to verify that, given the right conditions, bonding doesn\u27t only occur with valence electrons, but with the inner p-shell electrons as well, much like what occurs in xenon chemistry. The difficulty of proving this experimentally is that working with fluorine is extremely difficult and dangerous, and has only been studied at high pressure in one earlier study. For the past two years our group has been working on developing a new field of science we call: Useful Hard X-ray Photochemistry. By utilizing the highly penetrating, highly focused, and highly ionizing characteristics of hard x-rays, we can decompose relatively safe and inert solid and liquid samples into simple molecules. We have successfully used our technique to produce O2, H2, N2, Cl2, and most recently F2 in situ within a diamond anvil cell. We have also successfully and safely combusted O2 and H2 into water by creating a segregated mixture of potassium perchlorate and ammonia borate within a diamond anvil cell. We have developed a new method to produce molecular fluorine in situ, giving us a safe mechanism to supply excess fluorine that is available to react with cesium in order to experimentally verify the theoretical prediction of the unexpected stoichiometries of cesium compounds. By using techniques such as x-ray absorption fine structure spectroscopy, x-ray diffraction, and Raman spectroscopy, coupled with our new techniques of in situ hard x-ray photochemistry, we sought to experimentally demonstrate this theoretical behavior of inner shell bonding and open the door to a better understanding of chemical bonding under extreme conditions. This thesis discusses the results of our attempt to synthesize these novel CsFn (n\u3e1) compounds