Structure and reactivity of As under extreme conditions: high pressure and high temperature synthesis of H-rich extended As-H structures

This proposal is aimed at investigating the crystalline structure of arsenic above 50 GPa and at exploring the high pressure and high temperature chemical reactivity of As with H2 for synthesizing new extended As-H phases. Experimental results from a previous beamtime (CH-5791) limited to 48 GPa suggest indeed the existence of a new incommensurate structure in As analogous to that of Sb-II, which has been reported in the heavier pnictogen but not yet in As, and the formation of a reaction product containing As-H bonds, possibly related to extended As-H phases with high H-content and high superconducting Tc predicted by theoretical calculations, but never experimentally observed so far. The outcomes of this study are relevant to fundamental chemistry of pnictogens under extreme conditions and to the high-pressure synthesis of new advanced materials.