Direct Evidence of Photoinduced Protonation-Site Switching in Flavins - Sotaro Ohara; Temma Yazawa; Keisuke Hirata; Jun-Hao Yu; Qian-Rui Huang; Jer-Lai Kuo; Gilles Grégoire; Masaaki Fujii; Otto Dopfer; Shun-ichi Ishiuchi (Journal of the American Chemical Society, 2026)