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-position with the aldehyde (CHO) group substituent. In this work, we intend to investigate the ultrafast decay dynamics of electronically excited 3-furfural using the femtosecond time-resolved photoelectron imaging technique. At pump wavelengths of 259.5, 238.6 and 218.3 nm, two alternative decay mechanisms for the S₂(¹ππ*) state are tentatively proposed and discussed. 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, respectively.