Catalyst Synthesis: NiPACN samples were synthesized by a modified version of the procedure reported previously for NiPACN with all materials purchased from Sigma Aldrich unless otherwise noted. Acrylonitrile (2 mL) and azobisisobutyornitrile (AIBN, 2 mg) in acetone ( were performed largely following the methods outlined in a prior report. Samples were loaded into quartz tubes (Technical Glass Products, 2 mm ID, 3 mm ID). Measurements were taken at BL09XU at SPring-8 in the "203 bunch" A-mode with 23.6 ns electron bunch spacing and the beam monochromated to 67.4 keV using a Si (333) high heat load monochromator and then a Si (111) low-energy filtering monochromator. Transmitted photons were quantified using a 61 Ni0.86V0.14 analyzer foil mounted on a velocity transducer for selecting energies by Doppler shift.