Tehlar Andres, Kraus Peter M, Wörner Hans Jakob
ETH Zürich, Laboratory for Physical Chemistry, Wolfgang-Pauli-Str. 10, CH-8093 Zürich.
Chimia (Aarau). 2013;67(4):207-12. doi: 10.2533/chimia.2013.207.
This review discusses a new method for probing the evolution of the valence-electron structure of molecules during chemical reactions. The method relies on the interaction of an intense infrared laser pulse with molecules that results in the emission of attosecond pulses (1 as = 10(-18) s) in a process known as high-harmonic generation. Time-resolved high-harmonic spectroscopy measures the phase and amplitude of attosecond pulses emitted from the reacting molecules through interference with the emission from the unexcited molecules. This coherent detection mechanism provides a high sensitivity to small excitation fractions and direct access to both the amplitude and the phase of attosecond pulses, the latter of which is otherwise very difficult to measure. These observables reveal several complementary aspects of excited-state photochemical dynamics such as dissociation, adiabatic wave-packet evolution and conical intersection dynamics.
本综述讨论了一种探测化学反应过程中分子价电子结构演化的新方法。该方法依赖于强红外激光脉冲与分子的相互作用，这会在一个被称为高次谐波产生的过程中导致阿秒脉冲（1阿秒 = 10⁻¹⁸秒）的发射。时间分辨高次谐波光谱通过与未激发分子的发射进行干涉，测量反应分子发射的阿秒脉冲的相位和振幅。这种相干检测机制对小激发分数具有高灵敏度，并能直接获取阿秒脉冲的振幅和相位，而后者通常很难测量。这些可观测量揭示了激发态光化学动力学的几个互补方面，如解离、绝热波包演化和锥形交叉动力学。
