Faris Gel'mukhanov

KTH Royal Institute of Technology, Tukholma, Stockholm, Sweden

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Publications (92)360.83 Total impact

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    ABSTRACT: This study demonstrates that a hybrid density functional theory/molecular mechanics ap- proach can be successfully combined with time-dependent wavepacket approach to predict the shape of optical bands for molecules in solutions, including vibrational fine structure. A key step in this treatment is the estimation of the inhomogeneous broadening based on the hybrid approach, where the polarization between solute and atomically decomposed solvent is taken into account in a self-consistent manner. The potential of this approach is shown by predicting optical absorption bands for three heterocyclic ketoimine difluoroborates in solution.
    The Journal of Physical Chemistry A 05/2015; DOI:10.1021/jp5094417 · 2.78 Impact Factor
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    ABSTRACT: The vibrationally resolved x-ray photoelectron spectra of X2Σg+(3σg-1) and B2Σu+(2σu-1) states of N2+ were recorded for different photon energies and orientations of the polarization vector. Clear dependencies of the spectral linewidths on the x-ray polarization, as well as on the symmetry of the final electronic states are observed. Contrary to the translational Doppler, the rotational Doppler broadening is sensitive to the photoelectron emission anisotropy. Based on theoretical modeling, we suggest that the different rotational Doppler broadenings observed for gerade and ungerade final states result from a Young's double slit interference phenomenon.
    Journal of Physical Chemistry Letters 04/2015; 6:1568-1572. DOI:10.1021/acs.jpclett.5b00325 · 7.46 Impact Factor
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    ABSTRACT: Double-slit experiments illustrate the quintessential proof for wave–particle complementarity. If information is missing about which slit the particle has traversed, the particle, behaving as a wave, passes simultaneously through both slits. This wave-like behaviour and corresponding interference is absent if ‘which-slit’ information exists. The essence of Einstein–Bohr's debate about wave–particle duality was whether the momentum transfer between a particle and a recoiling slit could mark the path, thus destroying the interference. To measure the recoil of a slit, the slits should move independently. We showcase a materialization of this recoiling double-slit gedanken experiment by resonant X-ray photoemission from molecular oxygen for geometries near equilibrium (coupled slits) and in a dissociative state far away from equilibrium (decoupled slits). Interference is observed in the former case, while the electron momentum transfer quenches the interference in the latter case owing to Doppler labelling of the counter-propagating atomic slits, in full agreement with Bohr’s complementarity.
    Nature Photonics 02/2015; 9(2):120-125. DOI:10.1038/NPHOTON.2014.289 · 29.96 Impact Factor
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    ABSTRACT: [Online Open Access] Due to the generally delocalized nature of molecular valence orbitals, valence-shell spectroscopies do not usually allow to specifically target a selected atom in a molecule. However, in X-ray electron spectroscopy, the photoelectron momentum is large and the recoil angular momentum transferred to the molecule is larger when the photoelectron is ejected from a light atom compared with a heavy one. This confers an extreme sensitivity of the rotational excitation to the ionization site. Here we show that, indeed, the use of high-energy photons to photoionize valence-shell electrons of hydrogen chloride offers an unexpected way to decrypt the atomic composition of the molecular orbitals due to the rotational dependence of the photoionization profiles. The analysis of the site-specific rotational envelopes allows us to disentangle the effects of the two main mechanisms of rotational excitation, based on angular momentum exchange between the molecule and either the incoming photon or the emitted electron.
    Nature Communications 05/2014; 5:3816. DOI:10.1038/ncomms4816 · 10.74 Impact Factor
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    ABSTRACT: A detailed study of inelastic x-ray scattering from the ground state to the ^{3}Σ_{g}(3σ_{g}^{-1}3s_{g}^{1}) state of the O_{2} molecule is presented. The observed angular anisotropy shows that the vibrational excitations within this final state are strongly dependent on the polarization of the incident radiation. The analysis demonstrates that this is a manifestation of interference between resonant and direct nonresonant inelastic x-ray scattering. This interference provides a new tool to monitor nuclear dynamics by relative rotation of the polarization vectors of the incident and scattered photons.
    Physical Review Letters 05/2013; 110(22):223001. DOI:10.1103/PhysRevLett.110.223001 · 7.51 Impact Factor
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    ABSTRACT: This paper reports an advanced study of the excited ionic states of the gas-phase nitrogen molecule in the binding-energy region of 22–34 eV, combining ultrahigh-resolution resonant photoemission (RPE) and ab initio configuration-interaction calculations. The RPE spectra are recorded for nine photon energies within the N 1s→π* absorption resonance of N2 by using a photon bandwidth that is considerably smaller than lifetime broadening, and the dependence on excitation energy of the decay spectra is analyzed and used for the first assignment of 12 highly overlapped molecular states. The effect on the RPE profile of avoided curve crossings between the final N2+ ionic states is discussed, based on theoretical simulations that account for vibronic coupling, and compared with the experimental data. By use of synchrotron radiation with high spectral brightness, it is possible to selectively promote the molecule to highly excited vibrational sublevels of a core-excited electronic state, thereby controlling the spatial distribution of the vibrational wave packets, and to accurately image the ionic molecular potentials. In addition, the mapping of the vibrational wave functions of the core-excited states using the bound final states with far-from-equilibrium bond lengths has been achieved experimentally for the first time. Theoretical analysis has revealed the rich femtosecond nuclear dynamics underlying the mapping phenomenon.
    Physical Review X 04/2013; 3:011017. DOI:10.1103/PhysRevX.3.011017 · 8.39 Impact Factor
  • Q Miao · J-C Liu · H Agren · J-E Rubensson · F Gel'mukhanov
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    ABSTRACT: X-ray lasing is predicted to ensue when molecules are pumped into dissociative core-excited states by a free-electron-laser pulse. The lasing is due to the population inversion created in the neutral dissociation product, and the process features self-trapping of the x-ray pulse at the gain ridge. Simulations performed for the HCl molecule pumped at the 2p_{1/2}→6σ resonance demonstrate that the scheme can be used to create ultrashort coherent x-ray pulses.
    Physical Review Letters 12/2012; 109(23):233905. DOI:10.1103/PhysRevLett.109.233905 · 7.51 Impact Factor
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    ABSTRACT: Born–Oppenheimer and Franck–Condon approximations are two major concepts in the interpretation of electronic excitations and modeling of spectroscopic data in the gas and condensed phases. We report large variations of the anisotropy parameter (β) for the fully resolved vibrational sub-states of the X2Πg electronic ground state of O+2 populated by participator resonant Auger decay following excitations of K-shell electrons into the σ☆ resonance by monochromatic x-rays. Decay spectra for light polarization directions parallel and perpendicular to the electron detection axis recorded at four different excitation energies in the vicinity of the O 1s → σ☆ transition are presented. Breakdown of the Born–Oppenheimer approximation is for the first time selectively observed for the lower vibrational sub-states, where two quantum paths—resonant and direct—leading to the same final cationic state exist. The higher vibrational sub-states can only be populated by resonant photoemission; hence no interference between these channels can occur.
    New Journal of Physics 11/2012; 14:113018. DOI:10.1088/1367-2630/14/11/113018 · 3.67 Impact Factor
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    ABSTRACT: We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl K edge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.
    The Journal of Chemical Physics 09/2012; 137(9):094311. DOI:10.1063/1.4749574 · 3.12 Impact Factor
  • Quan Miao · Hong-Juan Ding · Yu-Ping Sun · Faris Gel'mukhanov · Chuan-Kui Wang
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    ABSTRACT: The optical limiting properties of a series of peripherally substituted phthalocyanines with different central metals and axial chloride ligand for nanosecond pulses have been studied by solving numerically the two-dimensional paraxial field equation together with the rate equations using the Crank–Nicholson method. It is shown that all of these compounds exhibit good optical limiting behaviour, and phthalocyanines with heavier central metals have better optical limiting performance due to the faster intersystem crossing caused by the enhanced spin–orbit coupling. The major mechanism of optical limiting for long pulses is the sequential (singlet–singlet)×(triplet–triplet) nonlinear absorption. Dynamics of populations is characterized mainly by the effective transfer time of the population from the ground state to the lowest triplet state. The long lifetime of the triplet state is important but not determinant. In addition, the performance of optical limiting strongly depends on the thickness and concentration of the absorber.
    Journal of Physics B Atomic Molecular and Optical Physics 04/2012; 45(8). DOI:10.1088/0953-4075/45/8/085402 · 1.92 Impact Factor
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    ABSTRACT: Electron-density distributions and potential-energy surfaces are important for predicting the physical properties and chem- ical reactivity of molecular systems. Whereas angle-resolved photoelectron spectroscopy enables the reconstruction of molecular-orbital densities of condensed species1 , absorption or traditional photoelectron spectroscopy are widely employed to study molecular potentials of isolated species. However, the information they provide is often limited because not all vibrational substates are excited near the vertical electronic transitions from the ground state. Moreover, many electronic states cannot be observed owing to selection rules or low transition probabilities. In many other cases, the extraction of the potentials is impossible owing to the high densities of over- lapping electronic states. Here we use resonant photoemission spectroscopy, where the absence of strict dipole selection rules in Auger decay enables access to a larger number of final states as compared with radiative decay. Furthermore, by populating highly excited vibrational substates in the intermediate core- excited state, it is possible to ‘pull out’ molecular states that were hidden by overlapping spectral regions before.
    Nature Physics 02/2012; 8:135-138. DOI:10.1038/NPHYS2159 · 20.60 Impact Factor
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    ABSTRACT: Resonant inelastic x-ray scattering spectra excited at the O1s−1π* resonance of liquid acetone are presented. Scattering to the electronic ground state shows a resolved vibrational progression where the dominant contribution is due to the C-O stretching mode, thus demonstrating a unique sensitivity of the method to the local potential energy surface in complex molecular systems. For scattering to electronically excited states, soft vibrational modes and, to a smaller extent, intermolecular interactions give a broadening, which blurs the vibrational fine structure. It is predicted that environmental broadening is dominant in aqueous acetone.
    Physical review. B, Condensed matter 10/2011; 84(13). DOI:10.1103/PhysRevB.84.132202 · 3.66 Impact Factor
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    ABSTRACT: Resonant inelastic soft x-ray scattering spectra excited at the dissociative 1σg → 3σu resonance in gas-phase O2 are presented and discussed in terms of state-of-the-art molecular theory. A new selection rule due to internal spin coupling is established, facilitating a deep analysis of the valence excited final states. Furthermore, it is found that a commonly accepted symmetry selection rule due to orbital parity breaks down, as the core hole and excited electron swap parity, thereby opening the symmetry forbidden 3σg decay channel.
    Journal of Physics B Atomic Molecular and Optical Physics 07/2011; 44(16):161002. DOI:10.1088/0953-4075/44/16/161002 · 1.92 Impact Factor
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    ABSTRACT: Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1σ(g) → 3σ(u) resonance in gas-phase O2 show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy.
    Physical Review Letters 04/2011; 106(15):153004. DOI:10.1103/PHYSREVLETT.106.153004 · 7.51 Impact Factor
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    ABSTRACT: The two-photon absorption (TPA) properties of four TPEB [tetrakis(phenylethynyl)benzene] derivatives (TD, para, ortho, and meta) with different donor/acceptor substitution patterns have been investigated experimentally by the femtosecond open-aperture Z-scan method and theoretically by the time-dependent density-functional theory (TDDFT) method. The four compounds show relatively large TPA cross sections, and the all-donor substituted species (TD) displays the largest TPA cross-section σ(2) = 520 ± 30 GM. On the basis of the calculated electronic structure, TD shows no TPA band in the lower energy region of the spectrum because the transition density is concentrated on particular transitions due to the high symmetry of the molecular structure. The centrosymmetric donor-acceptor TPEB para shows excitations resulting from transitions centered on D-π-D and A-π-A moieties, as well as transition between the D-π-D and A-π-A moieties; this accounts for the broad nature of the TPA bands for this compound. Calculations for two noncentrosymmetric TPEBs (ortho and meta) reveal that the diminished TPA intensities of higher-energy bands result from destructive interference between the dipolar and three-state terms. The molecular orbitals (MOs) of the TPEBs are derivable with linear combinations of the MOs of the two crossing BPEB [bis(phenylethynyl)benzene] derivatives. Overall, the characteristics of the experimental spectra are well-described based on the theoretical analysis.
    The Journal of Physical Chemistry A 01/2011; 115(2):105-17. DOI:10.1021/jp107044w · 2.78 Impact Factor
  • Yong Zhou · Quan Miao · Yu-Ping Sun · Faris Gel'mukhanov · Chuan-Kui Wang
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    ABSTRACT: The dynamical two-photon absorption (TPA) cross section as well as optical limiting of a 4,4'-bis(dimethylamino) stilbene (BDMAS) molecular medium for the nanosecond and femtosecond laser pulses is studied. This molecular medium can be described by a cascade three-level model in the visible light regime. Our numerical results show that the BDMAS molecular medium exhibits a strong optical limiting behaviour. The saturation TPA in the femtosecond time domain can be observed, and materials with larger nonlinear absorption cross sections would be much easier to saturate. Due to the contribution of the two-step TPA, the dynamical TPA cross section of BDMAS for nanosecond pulses is about three orders of magnitude larger than that for ultrashort femtosecond pulses. Special attention has been paid to the solvent effects on the optimal limiting performance. With an enhancement of the polarity of solvents, the dynamical optical limiting window becomes broader. In the origin of optical limiting, the dynamical TPA cross section of BDMAS decreases when the polarity of solvents increases, which is in good agreement with the experiment.
    Journal of Physics B Atomic Molecular and Optical Physics 01/2011; 44(3):035103. DOI:10.1088/0953-4075/44/3/035103 · 1.92 Impact Factor
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    ABSTRACT: Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s → a(1g)* inner-shell excitation by circularly polarized x rays in SF(6). In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.
    Physical Review Letters 12/2010; 105(23):233001. DOI:10.1103/PHYSREVLETT.105.233001 · 7.51 Impact Factor
  • Faris Gel'mukhanov · Hans Agren
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 08/2010; 30(35). DOI:10.1002/chin.199935321

Publication Stats

2k Citations
360.83 Total Impact Points


  • 2000–2014
    • KTH Royal Institute of Technology
      • Division of Theoretical Chemistry and Biology
      Tukholma, Stockholm, Sweden
    • University of Rome Tor Vergata
      Roma, Latium, Italy
  • 2013
    • SOLEIL synchrotron
      Gif, Île-de-France, France
  • 2012
    • Shandong Normal University
      Chi-nan-shih, Shandong Sheng, China
  • 1996–2010
    • Linköping University
      • Department of Physics, Chemistry and Biology (IFM)
      Linköping, Östergötland, Sweden
  • 2006–2007
    • Sophia University
      • Division of Physics
      Edo, Tōkyō, Japan
    • University at Buffalo, The State University of New York
      • Institute for Lasers, Photonics and Biophotonics
      Buffalo, NY, United States
    • Tohoku University
      • Institute of Multidisciplinary Research for Advanced Materials (IMRAM)
      Miyagi, Japan
  • 2002–2003
    • Uppsala University
      • Department of Physics and Astronomy
      Uppsala, Uppsala, Sweden