Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette F-91191, France.
J Chem Phys. 2017 Jul 7;147(1):013902. doi: 10.1063/1.4974150.
We investigate the photodynamics of the 2-methylallyl radical by femtosecond time-resolved photoelectron imaging. The experiments are accompanied by field-induced surface hopping dynamics calculations and the simulation of time-resolved photoelectron intensities and anisotropies, giving insight into the photochemistry and nonradiative relaxation of the radical. 2-methylallyl is excited at 236 nm, 238 nm, and 240.6 nm into a 3p Rydberg state, and the subsequent dynamics is probed by multiphoton ionization using photons of 800 nm. The photoelectron image exhibits a prominent band with considerable anisotropy, which is compatible with the result of theory. The simulations show that the initially excited 3p state is rapidly depopulated to a 3s Rydberg state, from which photoelectrons of high anisotropy are produced. The 3s state then decays within several 100 fs to the D (nπ) state, followed by the deactivation of the D to the electronic ground state on the ps time scale.
我们通过飞秒时间分辨光电子成像研究了 2-甲基丙烯基自由基的光动力学。实验伴随着场诱导表面跳跃动力学计算和时间分辨光电子强度和各向异性的模拟，深入了解了自由基的光化学和非辐射弛豫。2-甲基丙烯基在 236nm、238nm 和 240.6nm 处被激发到 3p 里德伯态，随后的动力学通过使用 800nm 光子的多光子电离来探测。光电子图像显示出一条具有相当各向异性的突出带，这与理论结果一致。模拟表明，最初激发的 3p 态迅速衰减到 3s 里德伯态，从该态产生高各向异性的光电子。然后，3s 态在几百飞秒内衰减到 D(nπ)态，随后 D 态在 ps 时间尺度上失活到电子基态。
