Coherent control of fragmentation of methyl iodide by shaped femtosecond pulse train

Coherent control of fragmentation of CH_3I using shaped femtosecond pulse train is investigated.The dissociation processes can be modulated by changing the separation of the shaped pulse train, and the yield of I^+under the irradiation of the optimal pulse is significantly increased compared with that using the transform-limited pulse.We discuss the control mechanism of dissociation processes with coherent interference in time domain.A three-pulse control model is proposed to explain the counterintuitive experimental results.

Ultrafast photoionization of ions and molecules by orthogonally polarized intense laser pulses: Effects of the time delay

We present the photoelectron momentum distributions(PMDs) and the photoelectron angular distributions(PADs) of He+ ions, aligned H2+ molecules and N2 molecules by intense orthogonally polarized laser pulses. Simulations are performed by numerically solving the corresponding two-dimensional time-dependent Schr?dinger equations(TDSEs) within the single-electron approximation frame. Photoelectron momentum distributions and photoelectron angular distributions present different patterns with the time delays Td, illustrating the dependences of the PMDs and PADs on the time delays by orthogonally polarized laser pulses. The evolution of the electron wavepackets can be employed to describe the intensity of the PADs from the TDSE simulations for N2 molecules.

Efficient solver for time-dependent Schrodinger equation with interaction between atoms and strong laser field

We present a parallel numerical method of simulating the interaction of atoms with a strong laser field by solving the time-depending Schr?dinger equation(TDSE) in spherical coordinates. This method is realized by combining constructing block diagonal matrices through using the real space product formula(RSPF) with splitting out diagonal sub-matrices for short iterative Lanczos(SIL) propagator. The numerical implementation of the solver guarantees efficient parallel computing for the simulation of real physical problems such as high harmonic generation(HHG) in these interaction systems.

The momentum distributions of triatomic molecular ion H_(3)^(2+) by intense laser pulses

We investigate theoretically the photoionization of triatomic molecular ion H_(3)^(2+) by numerically solving the two-dimensional time-dependent Schrödinger equations under Bohn-Oppenheimer approximation.The results show that the photoelectron momentum distributions(PMDs)of H_(3)^(2+) with different initial states are strongly dependent on the laser ellipticities and molecular orbital symmetry,and the PMDs of degenerate electronic states E^(±)are mirror images.Also,for degenerate electronic states E^(±),vortex structures appear in the PMDs by the counter-rotating circularly polarized laser pulses as the time delay between the two pulses increases,which can be explained by multicenter ionization and ultrafast photoionization model.

Controlling continuum wavepacket interference by two-color laser field in over-the-barrier ionization regime

Continuum wavepacket interference is investigated by numerically solving the time-dependent SchrSdinger equation for the interaction of hydrogen atoms with laser fields. The obtained wavepacket evolution indicates that, in the over-the-barrier ionization regime （1016 W/cm2）, the continuum-continuum （CC） interference of ionizing electrons becomes the main process in high- order harmonics generation （HHG）, compared with continuum-bound （CB） transition, as reported by Kohler et al. [Phys. Rev. Lett. 105（20）, 203902 （2010）]. We propose a two-color laser field scheme for controlling the quantum trajectories of ionizing electrons and for extending the CC harmonic energy. As a result, a high energy platform occurs in the HHG spectrum, which entirely originates from the CC harmonics, with a cutoff adjustable by the relative phase of the two-color fields. This provides further understanding of the dynamic feature of atoms and molecules in super intense laser fields and provides an opportunity to image the atomic or molecular potential.