Excited state hydrogen transfer dynamics in phenol-(NH3)2 studied by picosecond UV-near IR-UV time-resolved spectroscopy
Excited state hydrogen transfer dynamics in phenol-(NH3)2 studied by picosecond UV-near IR-UV time-resolved spectroscopy
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DOI：
10.1039/c9cp06369b
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发表时间：
2020-03-14
影响因子：
3.3
通讯作者：
Fujii, Masaaki
中科院分区：
文献类型：
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作者：
Ishiuchi, Shun-ichi;Kamizori, Junko;Fujii, Masaaki
苯酚(PhOH)-(NH3)(2)簇中激发态氢转移(ESHT)的时间演化已通过三色皮秒(ps)紫外(UV)-近红外(NIR)-UV泵浦-探针离子浸光谱法测量。反应产物 & x2d9;NH4NH3 的形成可通过 3p-3s 里德伯跃迁的近红外吸收来检测。所有电子振动水平的 ESHT 反应都显示双指数时间演化，甚至从 S-1 原点开始也是如此。基于双指数时间演化，表明存在通过三重态 pi sigma* 态的第二条反应路径，这给出了慢分量。从 S-1 原点开始的 ESHT 反应的快速时间演化被测量为 268 ps，比 PhOH-(NH3)(3) 慢 10 倍，并且表明 pi pi* 和反应性 pi sigma* 态之间存在更高的势垒。 ESHT 反应速率的尺寸依赖性基于由于 pi pi* 电势表面中的质子转移状态造成的电势畸变进行了讨论。
Time-evolutions of excited state hydrogen transfer (ESHT) in phenol (PhOH)-(NH3)(2) clusters have been measured by three-color picosecond (ps) ultraviolet (UV)-near infrared (NIR)-UV pump-probe ion dip spectroscopy. The formation of a reaction product, & x2d9;NH4NH3, is detected by its NIR absorption due to a 3p-3s Rydberg transition. The ESHT reactions from all of the vibronic levels show biexponential time-evolutions, even from the S-1 origin. Based on the biexponential time-evolution, it is suggested that there is a second reaction path via the triplet pi sigma* state, which gives the slow component. The fast time-evolution of the ESHT reaction from the S-1 origin is measured to be 268 ps, which is 10-times slower than that in PhOH-(NH3)(3), and a higher barrier between the pi pi* and reactive pi sigma* states is suggested. The size dependence of the ESHT reaction rates is discussed based on a potential distortion due to the proton transferred state in the pi pi* potential surface.