confidence that a significant fraction of the initial α-cleavage reaction takes place from the ketone singlet excited state, that the originally formed diarylmethyl-acyl radical pair loses CO in the crystal with time constants in the sub-nanosecond regime, and that the secondary bis(diarylmethyl) triplet radical pair has a lifetime limited by the rate of intersystem crossing of ca. 70 ns.
最近的工作表明,在四芳基
丙酮的纳米晶 (NC) 悬浮液中由脉冲激光激发产生的二芳基
甲基自由基构成了用于固态光脱羰反应详细机理分析的有价值的探针。在其中一个α-碳上具有不同取代基的酮的纳米晶悬浮液中使用反应量子产率和激光闪光光解的组合,我们能够自信地表明初始α-裂解反应的很大一部分发生在酮单线态激发态,最初形成的二芳基甲基-酰基自由基对在亚纳秒范围内以时间常数失去晶体中的 CO,并且二级双(二芳基甲基)三线态自由基对的寿命受系统间交叉速率的限制约 70 纳秒。