3-糠醛分子是呋喃分子的一个醛基取代衍生物,其呋喃环上3号位的氢原子被醛基所取代.本文试图利用飞秒时间分辨光电子成像的实验方法研究3-糠醛分子S2(1ππ*)态的超快衰变动力学.在259.5,238.6和218.3 nm的泵浦激发波长下,讨论了两种可能的S2(1ππ*)态衰变机制.具体而言,暂时更倾向于以下机制.一部分S2(1ππ*)态上的波包经历了亚皮秒的弛豫过程布居到了S1(1nπ*)态,随后在大概4 ps时间尺度下发生了由S1(1nπ*)态到T2(3ππ*)态的系间窜越.而T2(3ππ*)态的进一步衰变过程与其振动能量密切相关.对于259.5,238.6和218.3 nm初始激发波长,T2(3ππ*)态的寿命分别为 1.6±0.2 ns,280±30 ps和50±10 ps.
Investigation of Ultrafast Excited-State Dynamics of 3-Furfural
3-Furfural(C5H4O2)is a furan(C4H4O)derivative compound formed by replacing the hydrogen(H)atom at the ring 3-posi-tion with the aldehyde(CHO)group sub-stituent.In this work,we intend to investi-gate the ultrafast decay dynamics of elec-tronically excited 3-furfural using the fem-tosecond time-resolved photoelectron imaging technique.At pump wavelengths of 259.5,238.6 and 218.3 nm,two alterna-tive decay mechanisms for the S2(1ππ*)state are tentatively proposed and dis-cussed.Specifically,we prefer to suggest that a fraction of the initially prepared wavepacket in the S2(1ππ*)state is likely to undergo the subpicosecond relaxation via the S1(1nπ*)state.Presumably the lower lying T2(3ππ*)state is subsequently populated on a～4 ps timescale via intersystem crossing from the minimum of the S1(1nπ*)state surface.The relaxation of the T2(3ππ*)state is sensitive to its vibrational excess energy and the value of its lifetime is 1.6±0.2 ns,280±30 ps and 50±10 ps for pump wavelengths of 259.5,238.6 and 218.3 nm,re-spectively.
NETL
NSTL
万方数据
