Controlling strong-field fragmentation of H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:mrow><mml:mrow><mml:mspace width="-0.16em" /><mml:mspace width="-0.16em" /><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>by temporal effects with few-cycle laser pulses

Anis, Fatima; Sayler, A. M.; Gaire, B.; Johnson, Nora G.; Parke, E.; Carnes, K. D.; Esry, B. D.; Ben‐Itzhak, I.

doi:10.1103/physreva.85.023405

Cited by 63 publications

(60 citation statements)

References 78 publications

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“…Initially, for the shortest pulse duration of 7 fs, it is clear that both dissociation paths are not spectrally separated but rather highly overlapped around a broad peak at 0.8 eV. This result is in agreement with earlier reports [13,18,19]. The feature is not reproduced by the Floquet predictions, as described earlier, a fact that was expected for such short pulses.…”

Section: B Pulse Duration Effectssupporting

confidence: 90%

“…Our calculations are seen to be in agreement with the measurements and reproduce their features at a great extent. Moreover, they have been compared to and found in very good agreement with similar calculations reported in [18,19].…”

Section: B Pulse Duration Effectssupporting

confidence: 77%

“…A variety of techniques have been developed in order to both study in detail the dissociation mechanisms but also in an attempt to control them suitably. Thus, methods and detection schemes based on typical pump-probe approaches [9][10][11], the control of the carrier envelope phase (CEP) of the laser pulse [12][13][14], the exploitation of the pulse duration [3,[15][16][17][18][19] and pulse wavelength [4,20,21], as well as the use of two-color fields have been reported in the literature [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

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Role of broadband-laser-pulse temporal extent in H2+photodissociation

et al. 2012

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Molecular hydrogen ion (H 2 + ) dissociation paths of bond softening (BS) and above threshold dissociation (ATD) are investigated exploiting few-cycle chirped laser pulses. 7-fs laser pulses are temporally broadened in a controlled way by the imposed positive chirp covering the range 7-55 fs. The dissociation of the H 2 + molecules via the BS and ATD paths is then systematically monitored as a function of the pulses duration in conditions of equal H 2 + yield. The experimental data show distinctive characteristics both in the energy dissociation spectral structure as well as in the yield as the pulse duration broadens. The interpretation of our experimental findings is supported by ab initio calculations based on the H 2 + dissociation time-dependent Schrödinger equation (TDSE) in a strong laser field, thus shedding light into the details of the underlying dissociation dynamics involving few-cycle pulses. The results are also analyzed within the Floquet picture discussing certain limits of its applicability. Finally, our experimental findings show strong molecular alignment for durations longer than 20 fs.

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Section: B Pulse Duration Effectssupporting

confidence: 90%

Section: B Pulse Duration Effectssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Role of broadband-laser-pulse temporal extent in H2+photodissociation

et al. 2012

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“…4(b)]. Threephoton ATD contributes at higher KER with a tail that extends to lower KER, but is negligible around 1.7 eV [47]. Therefore, the 3-photon ATD likely does not play a major role in the observed asymmetry.…”

Section: Pacs Numbers: XXXmentioning

confidence: 99%

Carrier-Envelope Phase Control over Pathway Interference in Strong-Field Dissociation ofH2+

et al. 2013

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The dissociation of an H + 2 molecular-ion beam by linearly polarized, carrier-envelope-phase-tagged 5 fs pulses at 4×10 14 W/cm 2 with a central wavelength of 730 nm was studied using a coincidence 3D momentum imaging technique. Carrier-envelope-phase-dependent asymmetries in the emission direction of H + fragments relative to the laser polarization were observed. These asymmetries are caused by interference of odd and even photon number pathways, where net-zero photon and 1-photon interference predominantly contributes at H + +H kinetic energy releases of 0.2 -0.45 eV, and net-2-photon and 1-photon interference contributes at 1.65 -1.9 eV. These measurements of the benchmark H + 2 molecule offer the distinct advantage that they can be quantitatively compared with ab initio theory to confirm our understanding of strong-field coherent control via the carrier-envelope phase. PACS numbers: XXXOne ultimate goal of ultrafast, strong-field laser science is to coherently control chemical reactions [1][2][3]. A prerequisite to achieving this goal is to understand the control mechanisms and reaction pathways. To this end, tailoring the electric field waveform of few-cycle laser pulses to control reactions and uncover the underlying physics has become a powerful tool [4][5][6]. It has been applied to the dissociative ionization of H 2 and its isotopologues [7][8][9][10][11][12] and has recently been extended to more complex diatomic molecules, such as CO [13][14][15], and to small polyatomic molecules [16,17].Conceptually, one of the most basic features of a fewcycle laser pulse to control is the carrier-envelope phase (CEP). When the laser's electric field is written as E(t) = E 0 (t) cos(ωt + φ), E 0 (t) is an envelope function, ω is the carrier angular frequency, and φ is the CEP. In fact, all of the few-cycle waveform experiments cited above used the CEP as the control parameter.For example, Kling et al. used 5 fs, 1.2×10 14 W/cm 2 pulses with stabilized CEP to dissociatively ionize D 2 and found asymmetries in the emission direction of D + ions for kinetic energy releases (KER) above 6 eV [7,8]. The diminished dissociation signal in a circularly polarized laser field indicated that recollision played a role. Recollision entails a tunnel-ionized electron undergoing a collision with its parent ion after acceleration by the oscillating laser field [18,19]. The energy exchange between the laser-driven electron and the parent ion can promote the D + 2 to the 2pσ u excited state. Coupling of the 2pσ u and 1sσ g states [20] on the trailing edge of the laser pulse during the dissociation of D + 2 was suggested as the explanation for the CEP-dependent asymmetry [7,8].Another example comes from Kremer et al. who exposed an H 2 target to 6 fs, 4.4×10 14 W/cm 2 CEPstabilized laser pulses and observed asymmetries for KER values between 0.4 and 3 eV [9] -energies they attributed to bond softening (BS) [21] and not electron recollision, which has higher KER. They proposed that the initial ionization of H 2 generates a coherent wav...

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“…In this paper, we systematically study laser intensity effects on the dissociation of H + 2 [34][35][36][37][38][39]. Depending on laser intensities and photon energies, H + 2 may dissociate along selected electronic potential curves, and the dissociative fragments gain different kinetic energies.…”

Section: Introductionmentioning

confidence: 99%

Influence of laser intensities on the dissociation of hydrogen molecular ions

2014

Phys. Rev. A

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We systematically study the influence of laser intensities on the dissociation of H + 2 in strong laser fields by numerically solving the time-dependent Schrödinger equation. In Ti:sapphire infrared (IR) laser fields, H + 2 mainly dissociates along 1sσ g and 2pσ u states. The mixture of these dissociative states results in the laser-intensitydependent electron asymmetric localization. When the dissociation process is dressed by a laser field with a very long wavelength, the potential surfaces 1sσ g and 2pσ u degenerate due to the Stark effect, hence the kinetic energy release is changed. When H + 2 is exposed to a strong ultraviolet (UV) pulse, H + 2 is pumped to several excited states by absorbing a few energetic photons, resulting in the molecular dissociation ending with several kinetic energy peaks. The discrepancy of simulation results from the numerical models with and without Born-Oppenheimer approximation are analyzed.

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Controlling strong-field fragmentation of H2+by temporal effects with few-cycle laser pulses

Cited by 63 publications

References 78 publications

Role of broadband-laser-pulse temporal extent in H2+photodissociation

Role of broadband-laser-pulse temporal extent in H2+photodissociation

Carrier-Envelope Phase Control over Pathway Interference in Strong-Field Dissociation ofH2+

Influence of laser intensities on the dissociation of hydrogen molecular ions

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