Multiple Core and Vibronic Coupling Effects in Attosecond Stimulated X-Ray Raman Spectroscopy

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• 作者：Weijie Hua ; Jason D. Biggs ; Yu Zhang ; Daniel Healion ; Hao Ren ; Shaul Mukamel
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2013
• 出版时间：December 10, 2013
• 年：2013
• 卷：9
• 期：12
• 页码：5479-5489
• 全文大小：690K
• 年卷期：v.9,no.12(December 10, 2013)
• ISSN：1549-9626

文摘

Attosecond Stimulated X-ray Raman Spectroscopy (SXRS) is a promising technique for investigating molecular electronic structure and photochemical processes with high spatial and temporal resolution. We present a theoretical study of SXRS from multiple core excitation sites of the same element. Two issues are addressed: interference between pathways contributing the signals from different sites and how nuclear vibrations influence the signals. Taking furan as a model system, which contains two types of carbons, C_伪 and C_尾, we performed time-dependent density functional theory calculations and computed the SXRS signals with two pulses tuned at the carbon K-edge. Our simulations demonstrate that the SXRS signal from the C_伪 and C_尾 sites are nonadditive, owing to the significant mixed contributions (C_伪 1s excitations by the pump pulse followed by C_尾 1s excitations by the probe, or vice verse). Harmonic vibrations linearly coupled to the electronic transitions are incorporated using the cumulant expansion. The nuclei act as a bath for electronic transitions which accelerate the decay of the time-domain signal. The frequency-domain spectrum is modified by a small red shift, and high-resolution fine-structure features are introduced.