In situ X-ray diffraction of shock-compressed diamondoid

Diamondoids are a unique class of materials with a general chemical formula of C$_{\mathrm{4n+6}}$H$_{\mathrm{4n+12\thinspace }}$and have hydrogen terminated structures superimposable onto a diamond lattice. Static compression of lower diamondoids (ada-, dia- and tria-mantane) revealed diamond synthesis at significantly reduced transformation energy compared with conventional carbon phases. For instance, at 15 GPa, triamantane transforms to diamond at 1200 K, while \textgreater 2000 K is required for graphite-to-diamond transition [1, 2]. We investigated the effects of polymorphism and intermediate phases on the diamondoid-to-diamond transformation using laser-driven shock compression in the Matter in Extreme Conditions end-station at the Linac Coherent Light Source. Sub-picosecond time-resolved X-ray diffraction on four diamondoids allowed for direct structural characterization of intermediate phases that lead to diamond transformation. Our preliminary results show pressure-induced amorphization of diamondoid before recrystallization to diamond. [1]T. Irifune \textit{et al.}, \quad Physics of the Earth and Planetary Interiors \textbf{143--144}, 593 (2004). [2] S. Park \textit{et al.}, manuscript submitted