Multidimensional X-Ray Spectroscopy of Valence and Core Excitations in Cysteine
TL;DR: 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.
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 $\boldsymbol{k}_\mathrm{I}=-\boldsymbol{k}_1+\boldsymbol{k}_2+\boldsymbol{k}_3$ and $\boldsymbol{k}_\mathrm{II}=\boldsymbol{k}_1-\boldsymbol{k}_2+\boldsymbol{k}_3$ 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.
Citations
More filters
01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
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
Cites background from "Multidimensional X-Ray Spectroscopy..."
...Comparing the 2D signals with different middle probe pulses would bring valuable insights on the complicated many-body interaction of localized excitations [63]....
[...]
...Calculated multidimensional SXRS signals reveal the coupling between various core and valence excitations localized at different x-ray chromorphores in cysteine (figure adapted with permission from [63]....
[...]
References
More filters
TL;DR: Several two-dimensional projections are shown and techniques to isolate different contributions to the coherent response of semiconductors are demonstrated, which reveal previously unobserved many-body correlations.
Abstract: We demonstrate optical two-dimensional Fourier transform spectroscopy of heavy- and light-hole excitons in GaAs quantum wells. This is enabled by active interferometric stabilization of the excitation pulse separation and of a reference pulse.
62 citations
TL;DR: The excited state dynamics and relaxation of electrons and holes in the photosynthetic reaction center of photosystem II are simulated using a two-band tight-binding model, which clearly reveal the exciton migration and the charge-separation processes.
Abstract: The excited state dynamics and relaxation of electrons and holes in the photosynthetic reaction center of photosystem II are simulated using a two-band tight-binding model. The dissipative exciton and charge carrier motions are calculated using a transport theory, which includes a strong coupling to a harmonic bath with experimentally determined spectral density, and reduces to the Redfield, the Forster, and the Marcus expressions in the proper parameter regimes. The simulated third order two-dimensional signals, generated in the directions −k1+k2+k3, k1−k2+k3, and k1+k2−k3, clearly reveal the exciton migration and the charge-separation processes.
60 citations
TL;DR: In this paper, expressions for the 2D-SXRS signal obtained using attosecond x-ray pulses are derived for trans-N-methyl acetamide (NMA) with broad bandwidth (181 as, 14.2 eV FWHM) pulses tuned to the oxygen and nitrogen K-edges.
Abstract: Expressions for the two-dimensional stimulated x-ray Raman spectroscopy (2D-SXRS) signal obtained using attosecond x-ray pulses are derived. The 1D- and 2D-SXRS signals are calculated for trans-N-methyl acetamide (NMA) with broad bandwidth (181 as, 14.2 eV FWHM) pulses tuned to the oxygen and nitrogen K-edges. Crosspeaks in 2D signals reveal electronic Franck-Condon overlaps between valence orbitals and relaxed orbitals in the presence of the core-hole.
58 citations
TL;DR: A deeper understanding of how electron correlation works could have a large impact in several research fields, such as biochemistry and biology, and trigger important developments in the design and optimization of electronic devices.
Abstract: Electron correlation, caused by the interaction among electrons in a multielectron system, manifests itself in all states of matter. A complete theoretical description of interacting electrons is challenging; different approximations have been developed to describe the fundamental aspects of the correlation that drives the evolution of simple (few-electron systems in atoms/molecules) as well as complex (multielectron wave functions in atoms, molecules, and solids) systems. Electron correlation plays a key role in the relaxation mechanisms that characterize excited states of neutral or ionized atoms and molecules populated by absorption of extreme ultraviolet (XUV) or X-ray radiation. The dynamics of these states can lead to different processes such as Fano resonance and Auger decay in atoms or interatomic Coulombic decay or charge migration in molecules and clusters. Many of these relaxation mechanisms are ubiquitous in nature and characterize the interaction of complex systems, such as biomolecules, adsorbates on surfaces, and hydrogen-bonded clusters, with XUV light. These mechanisms evolve typically on the femtosecond (1 fs=10(-15) s) or sub-femtosecond timescale. The experimental availability of few-femtosecond and attosecond (1 as=10(-18) s) XUV pulses achieved in the last 10 years offers, for the first time, the opportunity to excite and probe in time these dynamics giving the possibility to trace and control multielectron processes. The generation of ultrashort XUV radiation has triggered the development and application of spectroscopy techniques that can achieve time resolution well into the attosecond domain, thereby offering information on the correlated electronic motion and on the correlation between electron and nuclear motion. A deeper understanding of how electron correlation works could have a large impact in several research fields, such as biochemistry and biology, and trigger important developments in the design and optimization of electronic devices.
55 citations
TL;DR: Crosspeaks in 2D signals reveal electronic Franck-Condon overlaps between valence orbitals and relaxed orbitals in the presence of the core-hole.
Abstract: Expressions for the two-dimensional Stimulated x-ray Raman Spectroscopy (2D-SXRS) signal obtained using attosecond x-ray pulses are derived. The 1D- and 2D-SXRS signals are calculated for trans-N-methyl acetamide (NMA) with broad bandwidth (FWHM ~14.2eV, 181 as) pulses tuned to the oxygen and nitrogen K-edges. Crosspeaks in 2D signals reveal electronic Franck-Condon overlaps between valence orbitals and relaxed orbitals in the presence of the core hole.
51 citations