Intensity-dependent multiorbital effect in high-order harmonics generated from aligned O 2 molecules

2016

Can. J. Chem.

The angle dependence of strong field ionization has been studied for a set of molecules containing triple bonds: HCCH, HCN, HCC–CN, H2N–CCH, H2N–CN, and H2N–CC–CN. Time-dependent configuration interaction (TDCI) with a complex absorbing potential was used to model strong field ionization by a linearly polarized seven-cycle 800 nm cosine squared pulse. The ionization yields have been calculated as a function of the laser intensity and polarization direction and plotted as three-dimensional surfaces. At low field strengths, the angular dependence can be understood in terms of ionization from the highest occupied orbitals. At higher laser intensities, ionization occurs from lower lying orbitals as well as from the highest occupied orbitals, as indicated by changes in the angular dependence of the ionization yield and by variations in the population analysis of the TDCI wavefunction with the intensity of the laser field. The ionization yield for directions parallel to the molecular axis increases more rapidly than perpendicular to the axis as the conjugation length is increased. NH2 substitution substantially increases the ionization yield along the molecular axis but has only a small effect for perpendicular directions.

Section: Introductionmentioning

confidence: 99%

Angle-dependent strong-field ionization of triple bonded systems calculated by time-dependent configuration interaction with an absorbing potential

Liao

2016

Can. J. Chem.

“…Beyond the SAE approximation, orbital tomography can be interpreted as probing the Dyson orbitals plus exchange terms . At higher intensities, angle-dependent ionization yields and HHG spectra also have contributions from lower lying orbitals. − These features appear to be the result of direct ionization from lower lying orbitals rather than excitation of the ion after ionization from the HOMO. Angle-dependent and channel-dependent ionization has also been measured in butadiene , and larger polyatomics …”

mentioning

confidence: 99%

“…These excited states are 4–8 eV higher than the ground state of the ion . Calculations of HHG spectra indicate that harmonic yields from the π u and σ g orbitals increase with increasing intensity …”

mentioning

confidence: 99%

Angle-Dependent Ionization of Small Molecules by Time-Dependent Configuration Interaction and an Absorbing Potential

Krause

2015

J. Phys. Chem. Lett.

The angle-dependence of strong field ionization of O2, N2, CO2, and CH2O has been studied theoretically using a time-dependent configuration interaction approach with a complex absorbing potential (TDCIS-CAP). Calculation of the ionization yields as a function of the direction of polarization of the laser pulse produces three-dimensional surfaces of the angle-dependent ionization probability. These three-dimensional shapes and their variation with laser intensity can be interpreted in terms of ionization from the highest occupied molecular orbital (HOMO) and lower lying orbitals, and the Dyson orbitals for the ground and excited states of the cations.

“…Orbital tomography and HHG can be used to determine the shape of the highest occupied molecular orbital (HOMO) . Lower lying orbitals have also been found to contribute to HHG spectra at high intensities. − …”

Section: Introductionmentioning

confidence: 99%

Angular Dependence of Strong Field Ionization of Haloacetylenes HCCX (X = F, Cl, Br, I), Using Time-Dependent Configuration Interaction with an Absorbing Potential

Hoerner

2018

J. Phys. Chem. C

Strong field ionization of haloacetylenes was simulated by timedependent configuration interaction using all single excitations and a complex absorbing potential. The angular dependence of ionization for HCCX was mapped with static electric fields in the range 0.01−0.06 atomic units and compared with the results for CH 3 X. HCCF ionizes primarily from the CC π orbital. HCCX (X = Cl, Br, I) compounds show increasing amounts of ionization from the halogen π-type lone pair orbitals and have a node perpendicular to the molecular axis. These shapes can be understood in terms of the energies and interactions of the halogen π-type lone pairs with the π orbitals of the CC triple bond.