High-harmonic spectroscopy of impulsively aligned 1,3-cyclohexadiene: Signatures of attosecond charge migration.

High-harmonic spectroscopy is an all-optical technique with inherent attosecond temporal resolution that has been successfully employed to reconstruct charge migration, electron-tunneling dynamics, and conical-intersection dynamics. Here, we demonstrate the extension of two key components of high-harmonic spectroscopy, i.e.

Dissociative ionization and Coulomb explosion of CH in two-color asymmetric intense laser fields.

Directional fragment ejection from a tetrahedral molecule CH in linearly polarized two-color ( and 2) asymmetric intense laser fields (50 fs, 1.4 × 10 W cm, 800 nm and 400 nm) has been studied by three-dimensional ion coincidence momentum imaging. The H fragment produced from dissociative ionization, CH → H + CH + e, is preferentially ejected on the larger amplitude side of the laser electric fields.

Asymmetric Dissociative Tunneling Ionization of Tetrafluoromethane in - 2 Intense Laser Fields.

Dissociative ionization of tetrafluoromethane (CF) in linearly polarized -2 ultrashort intense laser fields (1.4 × 10 W/cm, 800 and 400 nm) has been investigated by three-dimensional momentum ion imaging. The spatial distribution of produced by CF → + F + e exhibited a clear asymmetry with respect to the laser polarization direction.

Helicity-dependent dissociative tunneling ionization of CF in multicycle circularly polarized intense laser fields.

Dissociative tunneling ionization of tetrafluoromethane (CF) in circularly polarized ultrashort intense laser fields (35 fs, 0.8 × 10 W cm, 1035 nm), CF → CF + e → CF + F + e, has been studied by three-dimensional electron-ion coincidence momentum imaging. The photoelectron angular distribution in the recoil frame revealed that the dissociative tunneling ionization occurs efficiently when the laser electric field points from F to C.

Structure factors for tunneling ionization rates of molecules: General grid-based methodology and convergence studies.

We present a general methodology for evaluating structure factors defining the orientation dependence of tunneling ionization rates of molecules, which is a key process in strong-field physics. The method is implemented at the Hartree-Fock level of electronic structure theory and is based on an integral-equation approach to the weak-field asymptotic theory of tunneling ionization, which expresses the structure factor in terms of an integral involving the ionizing orbital and a known analytical function. The evaluation of the required integrals is done by three-dimensional quadrature which allows calculations using conventional quantum chemistry software packages.