Electronic movement flashing into view Numerous chemical processes begin with ionization: the ejection of an electron from a molecule. What happens in immediate aftermath that event? Kraus et al. explored this question iodoacetylene by detecting and analyzing spectrum emitted high harmonics (see Perspective Ueda). They traced migration residual positively charged hole along molecular axis on time scale faster than quadrillionth second. thereby characterized capacity laser field to steer...

Dissociation probabilities and populations of excited vibrational states are calculated numerically for interaction a Morse oscillator with chirped, ultrashort (${\mathit{t}}_{\mathit{p}}$${10}^{\mathrm{\ensuremath{-}}11}$ sec), intense laser pulse. It is shown that if the pulse frequency \ensuremath{\omega}(t) decreases at specific rate adapted to molecular anharmonicity, dissociation probability many orders magnitude higher than monochromatic same intensity. Such pulses should be useful...

We present a method for producing single circularly polarized attosecond pulse by an intense few cycle elliptically laser combined with terahertz field from numerical solutions of the time-dependent Schr\"odinger equation molecular ion ${\mathrm{H}}_{2}^{+}$. It is found that in presence 62.5 THz ($\ensuremath{\lambda}=4800\text{ }\text{ }\mathrm{nm}$) at intensity $\ensuremath{\sim}{10}^{14}\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$, 114 as can be generated elliptical wavelength 400 nm...

Coherent excitation of molecules with laser pulses are usually described by coupled time-dependent linear parabolic partial differential equations, i.e., Schrödinger equations. Numerical solutions these equations based on splitting (factorization) the exponential form evolution operator or propagator examined for accuracy amplitude and phase as a function various unitary schemes.

The time-dependent Schr\"odinger equation for the one-dimensional ${\mathrm{H}}_{2}^{+}$ molecule (with both nuclear and electronic degrees of freedom included) was solved numerically to study dissociative ionization. A wave-function splitting technique used with projections onto Volkov states, which allows one circumvent problem lost information on electron flux due absorbing boundary methods. This us calculate above-threshold ionization (ATI) photo kinetic-energy spectra in presence moving...

The harmonic-generation (HG) spectra of the ${\mathrm{H}}_{2}^{+}$ molecular ion generated by short, intense, linearly polarized laser pulses are calculated nonperturbatively solving a three-dimensional time-dependent Schr\"odinger equation. It is found that while radiates in similar manner to an atomic system such as H or ${\mathrm{He}}^{+}$ at high frequencies, high-vibrational states large internuclear distances behaves analogously two-level relatively-long-wavelength field. will be shown...

The time-dependent Schr\"odinger equation for ${\mathrm{H}}_{2}^{+}$ in a strong laser field is solved numerically model that uses the exact three-body Hamiltonian with one-dimensional nuclear motion restricted to direction of electric field. influence ionization on possible stabilization against dissociation investigated. Unexpectedly high rates from vibrational states, exceeding those neutral atomic hydrogen, are found. as functions internuclear distance R were also calculated fixed...

A two-step model of Coulomb explosions diatoms in intense laser fields is presented. In this the molecule loses several electrons when atoms are at equilibrium internuclear distance and then fast occur until products reach a critical Rc approximately=9 Bohr, which additional lost due to recently discovered maxima ionization rates occurring R=Rc. Then subsequent explosion for higher-charged ions takes place. The total combined energy agrees well with experimental results, showing striking...

Abstract Analytical predissociation linewidths are derived from the scattering solutions to two-state curve crossing problem. Four cases considered: ‘inner’ and ‘outer’ crossings in ‘weak’ or ‘strong’ coupling limits. It is shown that each case take form Γ = Γo cos2 η, where Γ0 related Landau-Zener transition probability η a phase integral between one of classical turning points known bound state curve, point continuum potential. decreasing function energy weak interaction limit, whereas for...

The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards critical distance ${R}_{c}$ is known charge resonance enhanced ionization (CREI). We make series of measurements this for ${\mathrm{CO}}_{2}$, varying pulse duration from 7 to 200 fs, order identify the states and time scales involved. find that $4+$ higher states, 100 fs scale required reach geometry $⟨{R}_{\mathrm{CO}}⟩\ensuremath{\approx}2.1\text{ }\text{ }\AA{}$...

Dynamic imaging of the molecular structure H(2)(+) is investigated by attosecond photoelectron holography. The interference between direct (reference) and backward rescattered (signal) photoelectrons in holography reveals birth time both channels spatial information structure. This confirmed simulations with a semiclassical model numerical solutions corresponding time-dependent Schrödinger equation, suggesting an time-resolved way obtained from laser induced rescattering ionized electrons....

Molecules constituted by different isotopes are in vibrational modes, making it possible to elucidate the mechanism of a chemical reaction via kinetic isotope effect. However, real-time observation motion isotopic nuclei molecules is still challenging due its ultrashort time scale. Here we demonstrate method monitor nuclear vibration with frequency modulation high-order harmonic generation (HHG) during laser-molecule interaction. In proof-of-principle experiment, report red shift HHG from H

We investigate photon-momentum sharing between an electron and ion following different photoionization regimes. find very partitioning of the photon momentum in one-photon ionization (the photoelectric effect) as compared to multiphoton processes. In effect, acquires a that is much greater than single $\ensuremath{\hbar}\ensuremath{\omega}/c$ [up ($8/5$) $\ensuremath{\hbar}\ensuremath{\omega}/c$] whereas strong-field regime, photoelectron only corresponding photons absorbed above field-free...

We theoretically investigate molecular photoelectron momentum distributions (MPMDs) by bichromatic [frequencies $({\ensuremath{\omega}}_{1},{\ensuremath{\omega}}_{2})]$ circularly polarized attosecond UV laser pulses. Simulations performed on aligned single-electron ${\mathrm{H}}_{2}{}^{+}$ numerically solving the corresponding three-dimensional time-dependent Schr\"odinger equation within a static nucleus frame show that MPMDs exhibit spiral structure for both co-rotating and...

We study enhanced ionization (EI) in asymmetric molecules by solving the 3D time-dependent Schr\"odinger equation for ${\mathrm{HeH}}^{2+}$ driven a few-cycle laser pulse linearly polarized along molecular axis. find that EI is much stronger when laser's carrier-envelope phase such electric field at peak of antiparallel to permanent dipole molecule (PDM). This dependence explained studying presence static field. When this PDM, energy dressed ground state moves up (with increasing...

The alignment dynamics of HCN, in a linear configuration, interacting with linearly polarized infrared laser pulses are studied numerically by exact (nonperturbative) solutions the time-dependent Schr\"odinger equation. alignment, respect to field polarization vector, is measured from angular distribution molecule using defined half angle ${\ensuremath{\theta}}_{1/2}.$ It shown that, at intensities $\mathcal{I}{=10}^{13}{\mathrm{W}/\mathrm{c}\mathrm{m}}^{2},$ can be achieved on subpicosecond...

The time-dependent Schr\"odinger equation for ${\mathrm{H}}_{2}$${\mathrm{}}^{+}$ in a 600-nm, intense (I\ensuremath{\geqslant}${10}^{14}$ W/${\mathrm{cm}}^{2}$) laser field is solved numerically model which uses the exact three-body Hamiltonian with one-dimensional nuclear motion restricted to direction of electric and three-dimensional electronic motion. High ionization rates are found, exceeding those neutral atomic hydrogen. This confirms, by rigorous, full dynamical calculation,...

Using $\mathrm{H}_{2}{}^{+}$ and $\mathrm{D}_{2}{}^{+}$, we observe two-surface population dynamics by measuring the kinetic energy of correlated ions that are created when ($\mathrm{D}_{2}{}^{+}$) ionize in short (40--140 fs) intense (${10}^{14}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) infrared laser pulses. Experimentally, find a modulation spectrum fragments. The spectral progression arises from hitherto unexpected spatial on excited state population, revealed Coulomb explosion. By...

Photodissociation probabilities of the ${\mathrm{H}}_{2}^{+}$ molecule calculated from numerical solutions time-dependent Schr\"odinger equation exhibit minima for high-intensity (${10}^{12}$I${10}^{14}$ W/${\mathrm{cm}}^{2}$) subpicosecond (100 fs) laser-pulse excitation. These are shown to correspond stabilization molecular ion and hence suppression photodissociation by creation stable laser-induced resonances a avoided-crossing mechanism between field-molecule potentials. Rotational...

We study analytically the photoionization of a coherent superposition electronic states and show that chirped pulses can measure attosecond time scale electron dynamics just as effectively transform-limited same bandwidth. The pulse with frequency-dependent phase creates interfering photoelectron amplitudes dynamics. at given pump-probe delay differential asymmetry oscillates function energy. Our results suggest important parameter for science is not duration, but bandwidth phased radiation.

We describe the generation of high-order elliptically and circularly polarized harmonic spectra in an aligned H+2 molecule ion by a combination two-colour ultrashort intense laser fields from numerical solutions corresponding time-dependent Schrödinger equation (TDSE). In bichromatic linearly or pulses with intensity I0 angular frequencies ω0 2ω0, it is found that maximum molecular (MHOHG) energies are functions internuclear distance. Based on classical model laser-induced electron...