An elementary molecular process can be characterized by the flow of particles (i.e., electrons and nuclei) that compose system. The flow, in turn, is quantitatively described flux time-sequence maps rate though specified surfaces observation) or, more detail, density. quantum theory concerted electronic nuclear fluxes (CENFs) associated with electronically adiabatic intramolecular processes presented. In particular, it emphasized how continuity equation employed to circumvent failure...

A pump-probe scheme for preparing and monitoring electron-nuclear motion in a dissociative coherent wave packet is explored from numerical solutions of non-Born-Oppenheimer time-dependent Schr\"odinger equation. mid-ir intense few-cycle probe pulse used to generate molecular high-order-harmonic generation (MHOHG) superposition two or more electronic-nuclear packets, prepared by femtosecond uv pump pulse. Varying the time delay between ir few hundreds attoseconds, MHOHG signal intensity shown...

The outcome of a pericyclic reaction is typically represented by arrows in the Lewis structure reactant, symbolizing net electron transfer. Quantum simulations can be used to interpret these terms electronic fluxes between neighboring bonds. are decomposed into contributions from electrons so-called orbitals, which account for mutation reactant that product, other valence and core orbitals. Series time-integrated assigned arrows, example 0.09-0.23 Cope rearrangement semibullvalene, with...

Abstract Time-resolved imaging of chemically active valence electron densities is a long-sought goal, as these electrons dictate the course chemical reactions. However, X-ray scattering always dominated by core and inert electrons, making time-resolved extremely challenging. Here we demonstrate an effective robust method, which emphasizes information encoded in weakly scattered photons, to image densities. The degenerate Cope rearrangement semibullvalene, pericyclic reaction, used example...

We study numerically pump-probe schemes for monitoring electron-nuclear motion in a dissociating molecule using midinfrared, intense few-femtosecond probe laser pulse which generates molecular high-order harmonics (MHOHG) from coherent superposition of wave packets prepared by weak femtosecond UV pump an initial bound state. show that varying the time delay between and few hundred attoseconds one alters MHOHG signal intensity many orders magnitude. The periodicity variations as function is...

We study pump-probe schemes for the real time observation of electronic motion on attosecond scale in molecular ion H(2)(+) and its heavier isotope T(2)(+) while these molecules dissociate femtosecond by solving numerically non-Born-Oppenheimer time-dependent Schrödinger equation. The UV pump laser pulse prepares a coherent superposition three lowest lying quantum states time-delayed mid-infrared, intense few-femtosecond probe subsequently generates high-order harmonics (MHOHG) from this...

One at a time or all once? Electronic fluxes during pericyclic reaction in the electronic ground state—exemplified for degenerate Cope rearrangement of semibullvalene—may proceed either synchronously asynchronously. Quantum simulations show that mechanism is determined by preparation reactants, example, synchronous cryogenic temperatures (tunneling) but asynchronous when induced selective laser pulses (with energy over barrier).

In laser-induced electron recollision, the returning wave packet retains structural information on its initial orbital.

The computation and analysis of photoelectron spectra (PES) is a fundamental technique in atomic molecular physics to study the structural dynamical properties target system, gain insight into process its ionization. Since first numerical solutions time-dependent Schrödinger equation (TDSE), numerous methods have been developed extract PES from calculated wave functions. However, most these severe limitations or are computationally very demanding. Here we present new family methods, based on...

Laser pump-probe schemes are explored numerically from a molecular time-dependent Schr\"odinger equation for monitoring attosecond electron motion by high-order-harmonic generation (HHG) coherent superposition of electronic states. Varying the time delay between probe and pump pulse on an scale alters HHG signal, leading to universal interference patterns. By using extended three-step recollision model, we show that various regular patterns in spectra, including continuous harmonic frequency...

The quantum theory of concerted electronic and nuclear fluxes (CENFs) during coherent periodic tunnelling from reactants (R) to products (P) back R in molecules with asymmetric double-well potentials is developed. results are deduced the solution time-dependent Schrödinger equation as a superposition two eigenstates; here, these states lowest doublet. This allows time evolutions resulting probability densities (EPDs NPDs) well CENFs be expressed terms simple sinusodial functions. These...

Using ab-initio non-Born-Oppenheimer simulations, we demonstrate amplification of XUV radiation in a high-harmonic generation type process using the example hydrogen molecular ion. A small fraction molecules is pumped to dissociative Rydberg state from which IR-assisted observed. We show that starting at sufficiently high IR driving field intensities ground become quasi-transparent for radiation, while due stabilization gain states maintained, thus leading lasing strongly driven states....

Abstract Pericyclic reactions with energies E well above the potential energy barrier B (case > ) proceed quantum nuclear flux densities 〈 j 〉 which are essentially proportional to ρ in femtosecond time domain. This corresponds definition of classical (cl) mechanics, cl = υ , almost constant velocity v . For other case < however, that is, domain coherent tunneling, we discover opposite trend, has maximum value close where is a minimum (in fact zero). The general conclusion mechanical...

The effect of nuclear motion on the synchronicity pincer type electronic rearrangement associated with bond making and breaking vice versa is investigated for degenerate Cope semibullvalene using a time-independent quantum chemical approach. We find that distinct paths along potential energy surface corresponding to synchronous involve asynchronous fluxes out old into new while entail rearrangement. In order demonstrate robustness results, various high-level methods including full structure...

The traditional wavepacket interferometry for nuclear densities is extended to flux densities. Accordingly, a molecule vibrating in an electronic excited state may be prepared such that at given time, the correspond broad distribution of molecular bond, from short long distances, which subdivided into chain lobes. We discover neighbouring lobes, or groups flow towards alternating directions, implying bond stretches and compressions. corresponding controlled by appropriate parameters two...

We present a time-dependent quantum mechanical analysis of electronic fluxes during large amplitude vibrations ethane, ethene and ethyne in the ground state. find that number electrons which participate concerted electron-nuclear decrease from ethane via to ethyne. Different initial conditions different sets "observer planes" monitoring rearrangement are tested demonstrate robustness results. This counter-intuitive result is due similar electron distributions single, double triple bonds...

Nacheinander oder gleichzeitig? Elektronenflüsse bei pericyclischen Reaktionen im elektronischen Grundzustand – beispielhaft die entartete Cope-Umlagerung von Semibullvalen können synchron asynchron ablaufen. Nach quantenmechanischen Simulationen wird Synchronizität der durch Präparation Reaktanten bestimmt, z. B. tiefen Temperaturen (Tunneln), aber selektiver Laseranregung (mit Energie über Barriere).

Using ab-initio simulations, we demonstrate amplification of extreme-ultraviolet (XUV) radiation during transient absorption in a high-harmonic generation type process using the example hydrogen atom. The strong IR driving field rapidly depletes initial ground state while populating excited electronic states through frustrated tunnelling, thereby creating population inversion. Concomitant XUV lasing is demonstrated by explicit inclusion seed our allowing thorough analysis terms this setup....

ABSTRACTWe investigate electronic quantum fluxes during large amplitude nuclear vibrations of hydrocarbon (HnCCHn), hydrosilicon (HnSiSiHn) and organosilicon (HnSiCHn) compounds with n = 1, 2, 3. The total are analysed in terms contributions from localised molecular orbital densities. Furthermore, the vibrationally induced charge transfer polar is investigated underlying fluxes.Display full sizeKEYWORDS: Electronic fluxelectron dynamicselectron densitychemical bondquantum dynamics...

Initial-state symmetry has been underappreciated in strong-field spectroscopies, where laser fields dominate the dynamics. We demonstrate numerically that transverse photoelectron phase structure arising from this is robust rescattering and manifests spectra. Interpretation of experiments need to take these effects into account. In turn, structures may enable attosecond super-resolution imaging with structured electron beams.