Department of Chemistry and Department of Physics & Astronomy, University of California Irvine, Irvine, California 92697, United States.
Université de Lyon, UJM-Saint-Étienne, CNRS, IOGS, Laboratoire Hubert Curien UMR 5516, Saint-Étienne 42023, France.
J Chem Theory Comput. 2023 Apr 25;19(8):2327-2339. doi: 10.1021/acs.jctc.3c00062. Epub 2023 Apr 4.
Tracing the evolution of molecular coherences can provide a direct, unambiguous probe of nonadiabatic molecular processes, such as the passage through conical intersections of electronic states. Two techniques, attosecond transient absorption spectroscopy (ATAS) and Transient Redistribution of Ultrafast Electronic Coherences in Attosecond Raman Signals (TRUECARS), have been used or proposed for monitoring nonadiabatic molecular dynamics. Both techniques employ the transmission of a weak attosecond extreme-ultraviolet or X-ray probe to interrogate the molecule at controllable time delays with respect to an optical pump, thereby extracting dynamical information from transient spectral features. The connection between these techniques has not been firmly established yet. In this theoretical study, we provide a unified description of both transient transmission techniques, establishing their relationship as limits of the same pump-probe spectroscopy technique for different pulse parameter regimes. We demonstrate this by quantum dynamical simulations of thiophenol photodissociation and show how complementary coherence information can be revealed by the two techniques.
追踪分子相干态的演化可以提供对非绝热分子过程的直接、明确的探测，例如通过电子态的锥形交叉点。两种技术，阿秒瞬态吸收光谱（ATAS）和阿秒拉曼信号中超快电子相干态的瞬态再分配（TRUECARS），已经被用于或被提议用于监测非绝热分子动力学。这两种技术都采用弱阿秒极紫外或 X 射线探针的传输，以相对于光学泵在可控的时间延迟处询问分子，从而从瞬态光谱特征中提取动力学信息。这两种技术之间的联系尚未牢固确立。在这项理论研究中，我们为这两种瞬态传输技术提供了一个统一的描述，将它们的关系确立为同一泵浦-探针光谱技术在不同脉冲参数范围下的极限。我们通过对巯基苯酚光解的量子动力学模拟证明了这一点，并展示了这两种技术如何揭示互补的相干信息。
