Though x-ray induced damage has been traditionally viewed as a nuisance, we use hard x-ray
induced photochemistry as a means to create novel synthetic pathways for novel materials (e.g.
doped polymeric CO [1]) and novel structures of known materials (e.g. CsO2) without the need for
catalysts or heat. Hard x-rays (>7keV) can penetrate sealed and pressurized chambers such as in
a diamond anvil cell (DAC) and are energetically far above any activation thresholds that may
prevent the synthesis of predicted yet undiscovered materials using conventional chemistry (order
of eV). They can also be resonantly absorbed near the K-[1] and L-edges of metal cations in salts to
cause electron transfer and drive chemical decomposition (and synthetic) reactions in a very
controlled way. This method was employed to safely release molecular fluorine in situ in a DAC
at high pressure to drive chemistry at extreme conditions (via e.g. XeF2 +hν→ Xe + F2)[2] enabling the
synthesis of HgF4 at high pressure which has been predicted and possibly observed2. This talk
will give a survey of our efforts to develop useful hard x-ray photochemistry as a novel way to
perform unique chemistry including the effort to verify some predictions of inner shell chemistry.

References
1. Goldberger, D., Evlyukhin, E., Cifligu, P., Wang, Y.. Pravica, M., Measurement of the
Energy and High-Pressure Dependence of X-ray-induced Decomposition of Crystalline
Strontium Oxalate, Journal of Physical Chemistry A, 2017, 121, 7108−7113 .
2. Pravica, M., Schyck, S., Harris, B., Cifligu, P., Billinghurst, B., Fluorine chemistry at
extreme conditions: possible synthesis of HgF4. Papers in Physics 2019 11, 110001-1-5.