The results of nanosecond-to-microsecond transient absorption measurements shown in Supplementary Fig. were obtained by the randomly-interleaved-pulse-train (RIPT) method. A picosecond laser, PL2210A (EKSPLA, 1 kHz, 25 ps, 8.7 μJ/pulse for 355 nm), and a supercontinuum (SC) radiation source (SC-450, Fianium, 20 MHz, pulse width: 50-100 ps depending on the wavelength, 450-1000 nm), were employed as the pump-pulse and probe sources, respectively. The measurements were performed in an aqueous solution placed in a 2-mm quartz cell under argon condition with stirring at room temperature.