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- ItemSub-laser-cycle control of coupled electron–nuclear dynamics at a conical intersection([London] : IOP, 2015) Richter, Maria; Bouakline, Foudhil; González-Vázquez, Jesús; Martínez-Fernández, Lara; Corral, Inés; Patchkovskii, Serguei; Morales, Felipe; Ivanov, Misha; Martín, Fernando; Smirnova, OlgaNonadiabatic processes play a fundamental role in the understanding of photochemical processes in excited polyatomic molecules. A particularly important example is that of radiationless electronic relaxation at conical intersections (CIs). We discuss new opportunities for controlling coupled electron–nuclear dynamics at CIs, offered by the advent of nearly single-cycle, phase-stable, mid-infrared laser pulses. To illustrate the control mechanism, a two-dimensional model of the NO2 molecule is considered. The key idea of the control scheme is to match the time scale of the laser field oscillations to the characteristic time scale of the wave packet transit through the CI. The instantaneous laser field changes the shape and position of the CI as the wave packet passes through. As the CI moves in the laser field, it 'slices' through the wave packet, sculpting it in the coordinate and momentum space in a way that is sensitive to the carrier-envelope phase of the control pulse. We find that the electronic coherence imparted on the sub-laser-cycle time scale manifests during much longer nuclear dynamics that follow on the many tens of femtosecond time scale. Control efficiency as a function of molecular orientation is analyzed, showing that modest alignment is sufficient for showing the described effects.
- ItemRecent developments in R-matrix applications to molecular processes(Bristol : IOP Publ., 2015) Mašín, Zdeněk; Harvey, Alex; Houfek, Karel; Brambila, Danilo S.; Morales, Felipe; Gorfinkiel, Jimena D.; Tennyson, Jonathan; Smirnova, OlgaWe report on recent developments of the UKRmol suite, an implementation of the molecular R- matrix method and present examples of the calculations (e.g. electron scattering, photoionization, high harmonic generation, etc.) it has enabled.
- ItemNO2molecular frame photoelectron angular distributions for a range of geometries using the R-matrix method(Bristol : IOP Publ., 2015) Brambila, Danilo S.; Harvey, Alex G.; Mašín, Zdeněk; Smirnova, OlgaWe present R-matrix calculations of photoionization from NO2, resolved in energy, angle, and both neutral and ionic state, for a range of molecular geometries, including in the vicinity of the 2A1/2B2 conical intersection.
- ItemSignatures of attosecond electronic–nuclear dynamics in the one-photon ionization of molecular hydrogen: analytical model versusab initiocalculations([London] : IOP, 2015) Medišauskas, Lukas; Morales, Felipe; Palacios, Alicia; González-Castrillo, Alberto; Plimak, Lev; Smirnova, Olga; Martín, Fernando; Ivanov, Misha YuWe present an analytical model based on the time-dependent WKB approximation to reproduce the photoionization spectra of an H2 molecule in the autoionization region. We explore the nondissociative channel, which is the major contribution after one-photon absorption, and we focus on the features arising in the energy differential spectra due to the interference between the direct and the autoionization pathways. These features depend on both the timescale of the electronic decay of the autoionizing state and the time evolution of the vibrational wavepacket created in this state. With full ab initio calculations and with a one-dimensional approach that only takes into account the nuclear wavepacket associated to the few relevant electronic states we compare the ground state, the autoionizing state, and the background continuum electronic states. Finally, we illustrate how these features transform from molecular-like to atomic-like by increasing the mass of the system, thus making the electronic decay time shorter than the nuclear wavepacket motion associated with the resonant state. In other words, autoionization then occurs faster than the molecular dissociation into neutrals.
- ItemReconstruction of the time-dependent electronic wave packet arising from molecular autoionization(Washington, DC [u.a.] : Assoc., 2018) Bello, Roger Y.; Canton, Sophie E.; Jelovina, Denis; Bozek, John D.; Rude, Bruce; Smirnova, Olga; Ivanov, Mikhail Y.; Palacios, Alicia; Martín, FernandoAutoionizing resonances are paradigmatic examples of two-path wave interferences between direct photoionization, which takes a few attoseconds, and ionization via quasi-bound states, which takes much longer. Time-resolving the evolution of these interferences has been a long-standing goal, achieved recently in the helium atom owing to progress in attosecond technologies. However, already for the hydrogen molecule, similar time imaging has remained beyond reach due to the complex interplay between fast nuclear and electronic motions. We show how vibrationally resolved photoelectron spectra of H2 allow one to reconstruct the associated subfemtosecond autoionization dynamics by using the ultrafast nuclear dynamics as an internal clock, thus forgoing ultrashort pulses. Our procedure should be general for autoionization dynamics in molecules containing light nuclei, which are ubiquitous in chemistry and biology.
- ItemRole of electronic correlations in photoionization of NO2 in the vicinity of the 2A1/2B2 conical intersection(Cambridge : The Royal Soc. of Chemistry, 2017) Brambila, Danilo S.; Harvey, Alex G.; Houfek, Karel; Mašín, Zdeněk; Smirnova, OlgaWe present the first ab initio multi-channel photoionization calculations for NO2 in the vicinity of the 2A1/2B2 conical intersection, for a range of nuclear geometries, using our newly developed set of tools based on the ab initio multichannel R-matrix method. Electronic correlation is included in both the neutral and the scattering states of the molecule via configuration interaction. Configuration mixing is especially important around conical intersections and avoided crossings, both pertinent for NO2, and manifests itself via significant variations in photoelectron angular distributions. The method allows for a balanced and accurate description of the photoionization/photorecombination for a number of different ionic channels in a wide range of photoelectron energies up to 100 eV. Proper account of electron correlations is crucial for interpreting time-resolved signals in photoelectron spectroscopy and high harmonic generation (HHG) from polyatomic molecules.
- ItemChiral dichroism in bi-elliptical high-order harmonic generation(Bristol : IOP Publ., 2018-02-28) Ayuso, David; Decleva, Piero; Patchkovskii, Serguei; Smirnova, OlgaThe application of strong bi-elliptically polarized laser fields to the generation of high-order harmonics in organic molecules offers exceptional opportunities for chiral recognition and chiral discrimination. These fields are made by combining an elliptically polarized fundamental, typically in the infrared range, with its counter-rotating second harmonic. Here we present a theoretical study of the harmonic emission from the chiral molecule propylene oxide in bi-elliptical fields. Our calculations include, for the first time in such a complex system, accurate photorecomination matrix elements, evaluated using the static-exchange density functional theory method. We show that bi-elliptical light can induce strong chiral dichroism in the harmonic spectra of chiral molecules in a broad range of harmonic numbers and ellipticities.
- ItemRoadmap on photonic, electronic and atomic collision physics: I. Light-matter interaction(Bristol : IOP Publ., 2019) Ueda, Kiyoshi; Sokell, Emma; Schippers, Stefan; Aumayr, Friedrich; Sadeghpour, Hossein; Burgdörfer, Joachim; Lemell, Christoph; Tong, Xiao-Min; Pfeifer, Thomas; Calegari, Francesca; Palacios, Alicia; Martin, Fernando; Corkum, Paul; Sansone, Giuseppe; Gryzlova, Elena V.; Grum-Grzhimailo, Alexei N.; Piancastelli, Maria Novella; Weber, Peter M.; Steinle, Tobias; Amini, Kasra; Biegert, Jens; Berrah, Nora; Kukk, Edwin; Santra, Robin; Müller, Alfred; Dowek, Danielle; Lucchese, Robert R.; McCurdy, C. William; Bolognesi, Paola; Avaldi, Lorenzo; Jahnke, Till; Schöffler, Markus S.; Dörner, Reinhard; Mairesse, Yann; Nahon, Laurent; Smirnova, Olga; Schlathölter, Thomas; Campbell, Eleanor E.B.; Rost, Jan-Michael; Meyer, Michael; Tanaka, Kazuo A.We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field. © 2019 IOP Publishing Ltd.
- ItemAttosecond control of spin polarization in electron–ion recollision driven by intense tailored fields([Bad Honnef] : Dt. Physikalische Ges., 2017-07-07) Ayuso, David; Jiménez-Galán, Alvaro; Morales, Felipe; Ivanov, Misha; Smirnova, OlgaTunnel ionization of noble gas atoms driven by a strong circularly polarized laser field in combination with a counter-rotating second harmonic generates spin-polarized electrons correlated to the spin-polarized ionic core. Crucially, such two-color field can bring the spin-polarized electrons back to the parent ion, enabling the scattering of the spin-polarized electron on the spin-polarized parent ion. Here we show how one can control the degree of spin polarization as a function of electron energy and recollision time by tuning the laser parameters, such as the relative intensities of the counter-rotating fields. The attosecond precision of the control over the degree of spin polarization opens the door for attosecond control and spectroscopy of spin-resolved dynamics.
- ItemA molecular clock for autoionization decay(Bristol : IOP Publ., 2017-06-14) Medišauskas, Lukas; Bello, Roger Y.; Palacios, Alicia; González-Castrillo, Alberto; Morales, Felipe; Plimak, Lev; Smirnova, Olga; Martín, Fernando; Ivanov, Misha YuThe ultrafast decay of highly excited electronic states is resolved with a molecular clock technique, using the vibrational motion associated to the ionic bound states as a time-reference. We demonstrate the validity of the method in the context of autoionization of the hydrogen molecule, where nearly exact full dimensional ab-initio calculations are available. The vibrationally resolved photoionization spectrum provides a time–energy mapping of the autoionization process into the bound states that is used to fully reconstruct the decay in time. A resolution of a fraction of the vibrational period is achieved. Since no assumptions are made on the underlying coupled electron–nuclear dynamics, the reconstruction procedure can be applied to describe the general problem of the decay of highly excited states in other molecular targets.