Hydrochloric acid (HCl, 36.5 to 38.0%) and trisodium citrate dihydrate (99%) were purchased from Fisher Scientific. Chemicals were used as received without further purification. X-ray flux conditions Aluminum absorber foils of 50 µm thickness were placed in the path of incoming X-rays prior to reflection from the interface to adjust the X-ray intensity as described in the SI. Ten foils were used in previous work, which did not show evidence of X-ray exposure effects. Six foils were used in the current work to yield a total X-ray flux on the sample of 3 × 10 !" photons/s which created the observed effects.