Atomic And Molecular Clusters

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Far-from-equilibrium dynamics of angular momentum in a quantum many-particle system (1906.12238v2)

Igor N. Cherepanov, Giacomo Bighin, Lars Christiansen, Anders Vestergaard Jørgensen, Richard Schmidt, Henrik Stapelfeldt, Mikhail Lemeshko

2019-06-28

We use laser-induced rotation of single molecules embedded in superfluid helium nanodroplets to reveal angular momentum dynamics and transfer in a controlled setting, under far-from-equilibrium conditions. As an unexpected result, we observe pronounced oscillations of time-dependent molecular alignment that have no counterpart in gas-phase molecules. Angulon theory reveals that these oscillations originate from the unique rotational structure of molecules in He droplets and quantum-state-specific transfer of rotational angular momentum to the many-body He environment on picosecond timescales. Our results pave the way to understanding collective effects of macroscopic angular momentum exchange in solid state systems in a bottom-up fashion.

Pure Molecular Beam of Water Dimer (1904.08716v3)

Helen Bieker, Jolijn Onvlee, Melby Johny, Lanhai He, Thomas Kierspel, Sebastian Trippel, Daniel A. Horke, Jochen Küpper

2019-04-18

Spatial separation of water dimer from water monomer and larger water-clusters through the electric deflector is presented. A beam of water dimer with purity and a rotational temperature of K was obtained. Following strong-field ionization using a fs laser pulse with a wavelength centered around nm and a peak intensity of we observed proton transfer and of the ionized water dimer broke apart into a hydronium ion and neutral OH.

Structure determination of the tetracene dimer in helium nanodroplets using femtosecond strong-field ionization (1907.03168v1)

Constant Schouder, Adam S. Chatterley, Florent Calvo, Lars Christiansen, Henrik Stapelfeldt

2019-07-06

Dimers of tetracene molecules are formed inside helium nanodroplets and identified through covariance analysis of the emission directions of kinetic tetracene cations stemming from femtosecond laser-induced Coulomb explosion. Next, the dimers are aligned in either one or three dimensions under field-free conditions by a nonresonant, moderately intense laser pulse. The experimental angular covariance maps of the tetracene ions are compared to calculated covariance maps for seven different dimer conformations and found to be consistent with four of these. Additional measurements of the alignment-dependent strong-field ionization yield of the dimer narrows the possible conformations down to either a slipped-parallel or parallel-slightly-rotated structure. According to our quantum chemistry calculations, these are the two most stable gas-phase conformations of the dimer and one of them is favorable for singlet fission.

Electronic structure of 3-transition-metal monoxide anions from calculations: ScO, TiO, CuO, and ZnO (1907.02181v1)

Young-Moo Byun, Serdar Öğüt

2019-07-04

The approximation to many-body perturbation theory is a reliable tool for describing charged electronic excitations, and it has been successfully applied to a wide range of extended systems for several decades using a plane-wave basis. However, the approximation has been used to test limited spectral properties of a limited set of finite systems (e.g. frontier orbital energies of closed-shell molecules) only for about a decade using a local-orbital basis. Here, we calculate the quasiparticle spectra of closed- and open-shell molecular anions with partially and completely filled 3 shells (i.e. with shallow and deep 3 states), ScO, TiO, CuO, and ZnO, using various levels of theory, and compare them to experiments to evaluate the performance of the approximation on the electronic structure of small molecules containing 3 transition metals. We find that the -only eigenvalue-only self-consistent scheme with fixed to the PBE level (@PBE), which gives the best compromise between accuracy and efficiency for solids, also gives good results for both localized () and delocalized () states of transition metal oxide molecules. The success of @PBE in predicting electronic excitations in these systems reasonably well is likely due to the fortuitous cancellation effect between the overscreening of the Coulomb interaction by PBE and the underscreening by the neglect of vertex corrections. Together with the absence of the self-consistent field convergence error (e.g. due to spin contamination in open-shell systems) and the multi-solution issue, the @PBE scheme gives the possibility to predict the electronic structure of complex real systems (e.g. molecule-solid and - hybrid systems) accurately and efficiently.

Reexamination of Tolman's law and the Gibbs adsorption equation for curved interfaces (1703.08719v2)

Martin Thomas Horsch, Stefan Becker, Michaela Heier, Jayant Kumar Singh, Felix Diewald, Ralf Müller, George Jackson, Jadran Vrabec, Hans Hasse

2017-03-25

In manuscript arXiv:1703.08719 [cond-mat.soft], it was claimed that the well-known deduction of Tolman's law is not rigorous, since Tolman's argument implies that two different definitions of the surface tension, called and in the manuscript, coincide. This claim is retracted as it can be shown by free-energy minimization that indeed holds for the Laplace radius. Joachim Gro\ss, Philipp Rehner, Carlos Vega, \O{}ivind Wilhelmsen, and the anonymous reviewers of The Journal of Chemical Physics contributed to finding the mistake in the manuscript.

Molecular size effects on diffraction resonances in positronium formation from fullerenes (1907.01900v1)

Paul-Antoine Hervieux, Anzumaan R. Chakraborty, Himadri S. Chakraborty

2019-07-01

We previously predicted [P.A. Hervieux et al., Phys. Rev. A \textbf{95}, 020701 (2017)] that owing to predominant electron capture by incoming positrons from the molecular shell, C acts like a spherical diffractor inducing resonances in the positronium (Ps) formation as a function of the positron impact energy. By extending the study for a larger C fullerene target, we now demonstrate that the diffraction resonances compactify in energy in analogy with the shrinking fringe separation for larger slit size in classical single-slit experiment. The result brings further impetus for conducting Ps spectroscopic experiments with fullerene targets, including target- and/or captured-level differential measurements. The ground states of the fullerenes are modeled in a spherical jellium frame of the local density approximation (LDA) method with the exchange-correlation functional based on the van Leeuween and Baerends (LB94) model potential, while the positron impact and Ps formation are treated in the continuum distorted-wave final state (CDW-FS) approximation.

Controlling Sub-Cycle Optical Chirality in the Photoionization of Chiral Molecules (1906.11325v2)

Shaked Rozen, Antoine Comby, Etienne Bloch, Sandra Beauvarlet, Dominique Descamps, Baptiste Fabre, Stephane Petit, Valerie Blanchet, Bernard Pons, Nirit Dudovich, Yann Mairesse

2019-06-26

Controlling the polarization state of electromagnetic radiation enables the investigation of fundamental symmetry properties of matter through chiroptical processes. Many strategies have been developed to reveal structural or dynamical information about chiral molecules, from the microwave to the extreme ultraviolet range. Most schemes employ circularly or elliptically polarized radiation, and more sophisticated configurations involve, for instance, light pulses with time-varying polarization states. In all these schemes, the polarization state of light is always considered as constant over one optical cycle. In this study, we zoom into the optical cycle in order to resolve and control a subcyle attosecond chiroptical process. We engineer an electric field whose instantaneous chirality can be controlled within the optical cycle, by combining two phase-locked orthogonally polarized fundamental and second harmonic fields. While the composite field has zero net ellipticity, it shows an instantaneous optical chirality which can be controlled via the two-color delay. We theoretically and experimentally investigate the photoionization of chiral molecules with this controlled chiral field. We find that electrons are preferentially ejected forward or backward relative to the laser propagation direction depending on the molecular handedness, similarly to the well-established photoelectron circular dichroism process. However, since the instantaneous chirality switches sign from one half cycle to the next, electrons ionized from two consecutive half cycles of the laser show opposite forward/backward asymmetries. This chiral signal provides a unique insight into the influence of instantaneous chirality in the dynamical photoionization process. Our results demonstrate the important role of sub-cycle polarization shaping of electric fields, as a new route to study and manipulate chiroptical processes.

Interactions of benzene, naphthalene, and azulene with alkali-metal and alkaline-earth-metal atoms for ultracold studies (1903.01378v2)

Paweł Wójcik, Tatiana Korona, Michał Tomza

2019-03-04

We consider collisional properties of polyatomic aromatic hydrocarbon molecules immersed into ultracold atomic gases and investigate intermolecular interactions of exemplary benzene, naphthalene, and azulene with alkali-metal (Li, Na, K, Rb, Cs) and alkaline-earth-metal (Mg, Ca, Sr, Ba) atoms. We apply the state-of-the-art \textit{ab initio} techniques to compute the potential energy surfaces (PESs). We use the coupled cluster method restricted to single, double, and noniterative triple excitations to reproduce the correlation energy and the small-core energy-consistent pseudopotentials to model the scalar relativistic effects in heavier metal atoms. We also report the leading long-range isotropic and anisotropic dispersion and induction interaction coefficients. The PESs are characterized in detail and the nature of intermolecular interactions is analyzed and benchmarked using symmetry-adapted perturbation theory. The full three-dimensional PESs are provided for selected systems within the atom-bond pairwise additive representation and can be employed in scattering calculations. Presented study of the electronic structure is the first step towards the evaluation of prospects for sympathetic cooling of polyatomic aromatic molecules with ultracold atoms. We suggest azulene, an isomer of naphthalene which possesses a significant permanent electric dipole moment and optical transitions in the visible range, as a promising candidate for electric field manipulation and buffer-gas or sympathetic cooling.

Tracking Attosecond Electronic Coherences Using Phase-Manipulated Extreme Ultraviolet Pulses (1906.07112v2)

Andreas Wituschek, Lukas Bruder, Enrico Allaria, Ulrich Bangert, Marcel Binz, Carlo Callegari, Giulio Cerullo, Paolo Cinquegrana, Luca Gianessi, Miltcho Danailov, Alexander Demidovich, Michele Di Fraia, Marcel Drabbels, Raimund Feifel, Tim Laarmann, Rupert Michiels, Najmeh Sadat Mirian, Marcel Mudrich, Ivaylo Nikolov, Finn H. O'Shea, Giuseppe Penco, Paolo Piseri, Oksana Plekan, Kevin Charles Prince, Andreas Przystawik, Primož Rebernik Ribič, Giuseppe Sansone, Paolo Sigalotti, Simone Spampinati, Carlo Spezzani, Richard James Squibb, Stefano Stranges, Daniel Uhl, Frank Stienkemeier

2019-06-17

The recent development of novel extreme ultraviolet (XUV) coherent light sources bears great potential for a better understanding of the structure and dynamics of matter. Promising routes are advanced coherent control and nonlinear spectroscopy schemes in the XUV energy range, yielding unprecedented spatial and temporal resolution. However, their implementation has been hampered by the experimental challenge of generating XUV pulse sequences with precisely controlled timing and phase properties. In particular, direct control and manipulation of the phase of individual pulses within a XUV pulse sequence opens exciting new possibilities for coherent control and multidimensional spectroscopy schemes, but has not been accomplished. Here, we overcome these constraints in a highly time-stabilized and phase-modulated XUV-pump, XUV-probe experiment which directly probes the evolution and dephasing of an inner subshell electronic coherence. This new approach, avoiding any XUV optics for direct pulse manipulation, opens up extensive applications of advanced nonlinear optics and spectroscopy at XUV wavelengths.

Recovery of high-energy photoelectron circular dichroism through Fano interference (1906.10550v1)

G. Hartmann, M. Ilchen, Ph. Schmidt, C. Küstner-Wetekam, C. Ozga, F. Scholz, J. Buck, F. Trinter, J. Viefhaus, A. Ehresmann, M. S. Schöffler, A. Knie, Ph. V. Demekhin

2019-06-25

It is commonly accepted that the magnitude of a photoelectron circular dichroism (PECD) is governed by the ability of an outgoing photoelectron wave packet to probe the chiral asymmetry of a molecule. To be able to accumulate this characteristic asymmetry while escaping the chiral ion, photoelectrons need to have relatively small kinetic energies of up to a few tens of electron volts. Here, we demonstrate a substantial PECD for very fast photoelectrons above 500 eV kinetic energy released from methyloxirane by a participator resonant Auger decay of its lowermost O -excitation. This effect emerges as a result of the Fano interference between the direct and resonant photoionization pathways, notwithstanding that their individual effects are negligibly small. The resulting dichroic parameter has an anomalous dispersion, i.e. it changes its sign across the resonance, which can be considered as an analogue of the Cotton effect in the X-ray regime.

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