Resonant Inelastic Scattering Spectra of Free Molecules with Vibrational Resolution

Hennies, Franz; Pietzsch, Annette; Berglund, Martin; Föhlisch, Alexander; Schmitt, Thorsten; Strocov, Vladimir N.; Karlsson, Hans; Andersson, Joakim; Rubensson, Jan‐Erik

doi:10.1103/physrevlett.104.193002

Cited by 143 publications

(149 citation statements)

References 25 publications

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“…These techniques can be used to spatially separate neutral molecules according to their quantum states [9], structural isomers [7,10], and cluster sizes [11]. These techniques promise advanced applications of well-defined samples of complex molecules in various research fields, e. g., modern spectroscopies [12,13] or the direct imaging of structural and chemical dynamics [2,[14][15][16]. However, successful implementation of these methods requires a thorough theoretical understanding of the molecule-field interaction for the involved molecular quantum states.…”

Section: Introductionmentioning

confidence: 99%

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

Chang

Filsinger

Sartakov

et al. 2014

Computer Physics Communications

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a b s t r a c tThe Controlled Molecule Imaging group (CMI) at the Center for Free Electron Laser Science (CFEL) has developed the CMIstark software to calculate, view, and analyze the energy levels of adiabatic Stark energy curves of linear, symmetric top and asymmetric top molecules. The program exploits the symmetry of the Hamiltonian to generate fully labeled adiabatic Stark energy curves.CMIstark is written in Python and easily extendable, while the core numerical calculations make use of machine optimized BLAS and LAPACK routines. Calculated energies are stored in HDF5 files for convenient access and programs to extract ASCII data or to generate graphical plots are provided. Chang et al. / Computer Physics Communications 185 (2014) [339][340][341][342][343][344][345][346][347][348][349] Nature of problem: Calculation of the Stark effect of asymmetric top molecules in arbitrarily strong dc electric fields in a correct symmetry classification and using correct labeling of the adiabatic Stark curves. Program summary Solution method:We set up the full M matrices of the quantum-mechanical Hamiltonian in the basis set of symmetric top wavefunctions and, subsequently, Wang transform the Hamiltonian matrix. We separate, as far as possible, the sub-matrices according to the remaining symmetry, and then diagonalize the individual blocks. This application of the symmetry consideration to the Hamiltonian allows an adiabatic correlation of the asymmetric top eigenstates in the dc electric field to the field-free eigenstates. This directly yields correct adiabatic state labels and, correspondingly, adiabatic Stark energy curves. Restrictions:The maximum value of J is limited by the available main memory. A modern desktop computer with 16 GB of main memory allows for calculations including all Js up to a values larger than 100 even for the most complex cases of asymmetric tops. Running time:Typically 1 s-1 week on a single CPU or equivalent on multi-CPU systems (depending greatly on system size and RAM); parallelization through BLAS/LAPACK. For instance, calculating all energies up to J = 25 of indole (vide infra) for one field strength takes 1 CPU-s on a current iMac.

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Section: Introductionmentioning

confidence: 99%

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

Chang

Filsinger

Sartakov

et al. 2014

Computer Physics Communications

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“…We present the first demonstration of stimulated resonant electronic x-ray Raman scattering (SRXRS) in an atomic gas. Resonant x-ray Raman scattering, also referred to as resonant inelastic x-ray scattering [12], was discovered in 1974 [11] and since then has developed into a standard tool to study electronic and vibrational excitations in solids [16][17][18], liquids [19], gases [20], and on surfaces and interfaces [21,22]. Although several theoretical feasibility studies of SRXRS have been presented [23][24][25][26], no experiment has yet demonstrated this effect.…”

mentioning

confidence: 99%

Stimulated Electronic X-Ray Raman Scattering

Weninger

Purvis²,

Ryan³

et al. 2013

Phys. Rev. Lett.

137

111

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We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state. [5][6][7] with pulse durations in the fs range and unprecedented high intensities, hold the potential for transferring these techniques to the x-ray domain, to ultimately study the coherent interplay of electronic and vibrational degrees of freedom with high temporal and spatial resolution [8][9][10]. The high penetration depth of x rays, combined with the element and chemical sensitivity of inelastic x-ray scattering [11][12][13] could open pathways to temporally resolve complex dynamical processes such as energy transfer in light harvesting complexes or reaction dynamics of catalytic processes [14,15]. However, the cross section for x-ray Raman scattering is small compared to that in the visible spectral domain. Therefore, even at XFELs, single shot measurements are challenging, especially in dilute samples in the gas or liquid phase.This difficulty could be overcome by stimulating the Raman scattering process to produce a strong coherent amplification of the signal. We present the first demonstration of stimulated resonant electronic x-ray Raman scattering (SRXRS) in an atomic gas. Resonant x-ray Raman scattering, also referred to as resonant inelastic x-ray scattering [12], was discovered in 1974 [11] and since then has developed into a standard tool to study electronic and vibrational excitations in solids [16][17][18], liquids [19], gases [20], and on surfaces and interfaces [21,22]. Although several theoretical feasibility studies of SRXRS have been presented [23][24][25][26], no experiment has yet demonstrated this effect.SRXRS would ideally be realized by a narrow-band, tuneable two-color x-ray source: one frequency to excite an electronic inner-shell transition and the other, lower frequency to dump an electron into the short-lived core hole. Although the production of narrow-band x rays has been realized [27,28], and schemes for two-color self seeded sources have been proposed [29], there are currently no tunable, two-color, coherent sources available to perform such an experiment. Instead of this ideal, presently unrealizable approach, we report the demonstration of SRXRS in neon with a self-amplified...

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“…These losses could be due to vibrational transitions (meV regime) or electronic transitions (eV regime). With high enough resolution in the fluorescence monochromator, losses due to different vibrational transitions can even be resolved in RIXS (86,87). Above the edge, the loss spectrum measured in RIXS becomes identical to the XES spectrum.…”

Section: Discussionmentioning

confidence: 98%

Electronic structure in real time: mapping valence electron rearrangements during chemical reactions

Wernet

2011

Phys. Chem. Chem. Phys.

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The interest in following the evolution of the valence electronic structure of atoms and molecules during chemical reactions on a femtosecond time scale is discussed. By explicitly mapping the occupied part of the electronic structure with femtosecond pump-probe schemes one essentially follows the electrons making the bonds while the bonds change. This holds the key to unprecedented insight into chemical bonding in short-lived intermediates and reveals the coupled motion of electrons and nuclei. Examples from the recent literature on small molecules and anionic clusters in the gas phase and on atoms and molecules on surfaces using lab-based femtosecond laser methods are used to demonstrate the case. They highlight how the evolution of the valence electronic structure can be probed with time-resolved photoelectron spectroscopy with ultraviolet (UV) probe photon energies of up to 6 eV. It is shown how new insight can be gained by extending the probing wavelength into the vacuumultraviolet (VUV) region to photon energies of 20 eV and more by accessing the whole occupied valence electronic structure with time-resolved VUV photoelectron spectroscopy.Finally, the importance of soft x-ray free-electron lasers with probe photon energies of several hundred eV and femtosecond pulses and in particular the key role of femtosecond timeresolved soft x-ray emission spectroscopy or resonant inelastic x-ray scattering for mapping the electronic structure during chemical reactions is discussed.2

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Resonant Inelastic Scattering Spectra of Free Molecules with Vibrational Resolution

Cited by 143 publications

References 25 publications

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

CMIstark: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields

Stimulated Electronic X-Ray Raman Scattering

Electronic structure in real time: mapping valence electron rearrangements during chemical reactions

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