Multidimensional x-ray spectroscopy of valence and core excitations in cysteine
14 Apr 2013-Journal of Chemical Physics (American Institute of Physics)-Vol. 138, Iss: 14, pp 144303-144303
TL;DR: In this paper, the coupling between localized core and delocalized valence excitation in two-and three-pulse stimulated x-ray Raman spectroscopy (SXRS) signals with frequency-dispersed probe was investigated.
Abstract: Several nonlinear spectroscopy experiments which employ broadband x-ray pulses to probe the coupling between localized core and delocalized valence excitation are simulated for the amino acid cysteine at the K-edges of oxygen and nitrogen and the K- and L-edges of sulfur. We focus on two-dimensional (2D) and 3D signals generated by two- and three-pulse stimulated x-ray Raman spectroscopy (SXRS) with frequency-dispersed probe. We show how the four-pulse x-ray signals kI=−k1+k2+k3 and k II =k1−k2+k3 can give new 3D insight into the SXRS signals. The coupling between valence- and core-excited states can be visualized in three-dimensional plots, revealing the origin of the polarizability that controls the simpler pump-probe SXRS signals.
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TL;DR: In this paper, the authors discuss recent experimental and theoretical developments in ultrafast X-ray absorption spectroscopies (XAS) and explore the new opportunities they offer, as well as the driving force for new theoretical methods permitting a detailed interpretation of the spectra in terms of the geometrical and electronic properties of the system.
181 citations
TL;DR: In this paper, the authors reviewed current achievements and capabilities in chemical dynamics from XTA spectroscopy based mainly on studies by the authors, collaborators, and cousers of the same facility and then outlined some future challenges and impacts in chemical sciences using pulsed X-rays from the third-generation synchrotron and the fourth-generation X-ray free-electron light sources.
Abstract: After over a decade of development, X-ray transient absorption (XTA) spectroscopy has become an increasingly important and common tool in following molecular structures in chemical reactions and to map out structural factors that could influence reaction pathways. The Perspective reviews current achievements and capabilities in chemical dynamics from XTA spectroscopy based mainly on studies by the authors, collaborators, and cousers of the same facility and then outlines some future challenges and impacts in chemical sciences using pulsed X-rays from the third-generation synchrotron and the fourth-generation X-ray free-electron light sources.
79 citations
TL;DR: This work shows how ultrafast hard X-ray pulses may be used to create localized electronic wavepackets in a metalloporphyrin dimer by combining the broad bandwidth of attosecond pulses with the localized nature of core orbitals results in a much higher degree of localization and temporal resolution than is possible with optical pulses.
Abstract: Understanding the excitation energy transfer mechanism in multiporphyrin arrays is key for designing artificial light-harvesting devices and other molecular electronics applications. Simulations of the stimulated X-ray Raman spectroscopy signals of a Zn/Ni porphyrin heterodimer induced by attosecond X-ray pulses show that these signals can directly reveal electron–hole pair motions. These dynamics are visualized by a natural orbital decomposition of the valence electron wavepackets.
42 citations
TL;DR: Bennett et al. as mentioned in this paper survey various possible types of multidimensional x-ray spectroscopy techniques and demonstrate the novel information they can provide about molecules, such as core-electronic structure and couplings, real-time tracking of impulsively created valence-electronics wavepackets and electronic coherences, and monitoring ultrafast processes such as nonadiabatic electron-nuclear dynamics near conical-intersection crossings.
Abstract: Author(s): Bennett, K; Zhang, Y; Kowalewski, M; Hua, W; Mukamel, S | Abstract: New x-ray free electron laser (XFEL) and high harmonic generation (HHG) light sources are capable of generating short and intense pulses that make x-ray nonlinear spectroscopy possible. Multidimensional spectroscopic techniques, which have long been used in the nuclear magnetic resonance, infrared, and optical regimes to probe the electronic structure and nuclear dynamics of molecules by sequences of short pulses with variable delays, can thus be extended to the attosecond x-ray regime. This opens up the possibility of probing core-electronic structure and couplings, the real-time tracking of impulsively created valence-electronic wavepackets and electronic coherences, and monitoring ultrafast processes such as nonadiabatic electron-nuclear dynamics near conical-intersection crossings. We survey various possible types of multidimensional x-ray spectroscopy techniques and demonstrate the novel information they can provide about molecules.
33 citations
TL;DR: The off-resonant scattering of a broadband X-ray pulse from a sample initially prepared in an arbitrary superposition of electronic states is calculated using a quantum electrodynamic framework and can guide future experimental studies on the structures of nano-particles and proteins.
Abstract: Using a quantum electrodynamic framework, we calculate the off-resonant scattering of a broadband X-ray pulse from a sample initially prepared in an arbitrary superposition of electronic states. The signal consists of single-particle (incoherent) and two-particle (coherent) contributions that carry different particle form factors that involve different material transitions. Single-molecule experiments involving incoherent scattering are more influenced by inelastic processes compared to bulk measurements. The conditions under which the technique directly measures charge densities (and can be considered as diffraction) as opposed to correlation functions of the charge-density are specified. The results are illustrated with time- and wavevector-resolved signals from a single amino acid molecule (cysteine) following an impulsive excitation by a stimulated X-ray Raman process resonant with the sulfur K-edge. Our theory and simulations can guide future experimental studies on the structures of nano-particles and proteins.
32 citations
References
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