I heard about these experiments several years ago, but hadn't dug into the research until now. Quite interesting work on the transmutation of mercury into gold in arc-lamps done in 1923 which was presented and discussed favorably by both The Royal Society and Nature at the time:
https://royalsocietypublishing.org/doi/abs/10.1098/rspa.1926.0120
https://www.nature.com/articles/114197a0
https://royalsocietypublishing.org/doi/abs/10.1098/rspa.1926.0120
https://www.nature.com/articles/114197a0