Contributions of inner-valence molecular orbitals and multiphoton resonances to high-order-harmonic generation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>: A time-dependent density-functional-theory study

Chu, Xi; Groenenboom, Gerrit C.

doi:10.1103/physreva.93.013422

Cited by 21 publications

(23 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Additional information can be gained by calculating the response for each Kohn-Sham orbital [40]. In that case we calculate the dipole acceleration from each Kohn-Sham state asd…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

High-order harmonic generation from highly excited states in acetylene

Mulholland

Dundas

2018

Phys. Rev. A

View full text Add to dashboard Cite

High-order harmonic generation (HHG) from aligned acetylene molecules interacting with mid infra-red (IR), linearly polarized laser pulses is studied theoretically using a mixed quantum-classical approach in which the electrons are described using time-dependent density functional theory while the ions are treated classically. We find that for molecules aligned perpendicular to the laser polarization axis, HHG arises from the highestoccupied molecular orbital (HOMO) while for molecules aligned along the laser polarization axis, HHG is dominated by the HOMO-1. In the parallel orientation we observe a double plateau with an inner plateau that is produced by ionization from and recombination back to an autoionizing state. Two pieces of evidence support this idea. Firstly, by choosing a suitably tuned vacuum ultraviolet pump pulse that directly excites the autoionizing state we observe a dramatic enhancement of all harmonics in the inner plateau. Secondly, in certain circumstances, the position of the inner plateau cut-off does not agree with the classical three-step model. We show that this discrepancy can be understood in terms of a minimum in the dipole recombination matrix element from the continuum to the autoionizing state. As far as we are aware, this represents the first observation of harmonic enhancement over a wide range of frequencies arising from autoionizing states in molecules.

show abstract

“…Additional information can be gained by calculating the response for each Kohn-Sham orbital [40]. In that case we calculate the dipole acceleration from each Kohn-Sham state asd…”

Section: Resultsmentioning

confidence: 99%

“…We note that the parallel cutoff is also consistent with ionization from the HOMO-2. We have calculated the HHG spectra arising from each occupied KohnSham orbital [40]; these are shown in Figs. 3(a) and 3(b) for the parallel and perpendicular orientations, respectively.…”

Section: B High-order Harmonic Generation: the Ir Pulsementioning

confidence: 99%

High-order harmonic generation from highly excited states in acetylene

Mulholland

Dundas

2018

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…Additional information can be gained by calculating the response for each Kohn-Sham orbital [55]. In that case we calculate the dipole acceleration for each state as…”

Section: High Harmonic Generationmentioning

confidence: 99%

Probing the role of excited states in ionization of acetylene

Dundas

Mulholland

Wardlow

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Ionization of acetylene by linearly-polarized, vacuum ultraviolet (VUV) laser pulses is modelled using timedependent density functional theory. Several laser wavelengths are considered including one that produces direct ionization to the first excited cationic state while another excites the molecules to a Rydberg series incorporating an autoionizing state. We show that for the wavelengths and intensities considered, ionization is greatest whenever the molecule is aligned along the laser polarization direction. By considering high harmonic generation we show that populating excited states can lead to a large enhancement in the harmonic yield. Lastly, angularly-resolved photoelectron spectra are calculated which show how the energy profile of the emitted electrons significantly changes in the presence of these excited states.

show abstract

“…Such involvement is usually related to the polarization direction of laser field in the molecular frame [7]. Sometimes resonances in photoelectron spectra also show up in high harmonic generation [6,8], indicating similar many-electron mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…While SAE based approaches have been successful in describing the interaction of inert gases with strong fields, more and more work on molecules reveals the involvement of orbitals lower in energy than the highest occupied orbital [5,6], suggesting the importance of many-electron mechanisms. Such involvement is usually related to the polarization direction of laser field in the molecular frame [7].…”

Section: Introductionmentioning

confidence: 99%

Tunneling ionization of the F4 and D6 states of vanadium: Exchange blockade

Chu

Groenenboom

2017

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

Using TDDFT calculations we compare tunneling ionization of the a 4 F ground state and the a 6 D first excited state of vanadium in laser fields of intensities between 1.4 and 4.0×10 13 W/cm 2 .The calculated ionization yields of the ground state of vanadium were already shown to agree well with experimental results [Chu and Groenenboom, Phys. Rev. A 94, 053417 (2016)]. We find that the tunneling ionization rate of the sextet state is lower than that of the quartet state. This is surprising, since the ionization potential of the sextet is lower than that of the quartet state.This finding, however, is consistent with the experimental observation that niobium, whose ground state is a 6 D 1/2 , has a much smaller ionization yield than vanadium (a 4 F 3/2 ), even though their ionization potentials are extremely close [Smits et al., Phys. Rev. Lett. 93, 213003 (2004)]. Our calculations demonstrate the existence of exchange blockade for the higher spin state. It arises from a strong field dynamic effect that the highest and second highest electrons mixing in the same set of unoccupied spin orbitals, which causes an isotropic attractive potential that confines the electrons close to the core.

show abstract

Contributions of inner-valence molecular orbitals and multiphoton resonances to high-order-harmonic generation ofN2: A time-dependent density-functional-theory study

Cited by 21 publications

References 27 publications

High-order harmonic generation from highly excited states in acetylene

High-order harmonic generation from highly excited states in acetylene

Probing the role of excited states in ionization of acetylene

Tunneling ionization of the F4 and D6 states of vanadium: Exchange blockade

Contact Info

Product

Resources

About