Excitation wavelength dependent S1‑state decay dynamics of 2-aminopyridine and 3-aminopyridine Baihui Feng, Dongyuan Yang, Yanjun Min, Qinghua Gao, Benjie Fang, Guorong Wu and Xueming Yang Abstract The decay dynamics of 2-aminopyridine and 3-aminopyridine excited to the S¬1 state is investigated using femtosecond time-resolved photoelectron imaging technique. The lifetime of the S1 state for both molecules shows a rapid decrease with the increase of the vibrational energy.