Gustavsson Thomas, Sarkar Nilmoni, Lazzarotto Elodie, Markovitsi Dimitra, Barone Vincenzo, Improta Roberto
J Phys Chem B. 2006 Jul 6;110(26):12843-7. doi: 10.1021/jp062266j.
The excited-state dynamics of 5-fluorouracil in acetonitrile has been investigated by femtosecond fluorescence upconversion spectroscopy in combination with quantum chemistry TD-DFT calculations ((PCM/TD-PBE0). Experimentally, it was found that when going from water to acetonitrile solution the fluorescence decay of 5FU becomes much faster. The calculations show that this is related to the opening of an additional decay channel in acetonitrile solution since the dark n/pi* excited state becomes near degenerate with the bright pi/pi* state, forming a conical intersection close to the Franck-Condon region. In both solvents, a S1-S0 conical intersection, governed by the out-of-plane motion of the fluorine atom, is active, allowing an ultrafast internal conversion to the ground state.
通过飞秒荧光上转换光谱结合量子化学TD-DFT计算（(PCM/TD-PBE0)），研究了5-氟尿嘧啶在乙腈中的激发态动力学。实验发现，从水溶液到乙腈溶液时，5FU的荧光衰减变得更快。计算表明，这与乙腈溶液中额外衰减通道的开启有关，因为暗的n/π激发态与亮的π/π态近乎简并，在接近弗兰克-康登区域形成了一个锥形交叉点。在两种溶剂中，由氟原子的面外运动控制的S1-S0锥形交叉点都是活跃的，允许超快内转换到基态。
