Charge-resonance-enhanced ionization of diatomic molecular ions by intense lasers

Zuo, Tao; Bandrauk, A. D.

doi:10.1103/physreva.52.r2511

Cited by 801 publications

(686 citation statements)

References 15 publications

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“…The 3 eV structure originates from enhanced ionization of H 2 + in the laser field at rather large internuclear distances (4 -6 a.u.) [40][41][42][43] which, for the 6.5 fs pulses used in the present experiments are only reached by the main part of the wave packet when the intensity has already significantly dropped down [36,40].…”

Section: Methodsmentioning

confidence: 98%

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Real-time observation of vibrational revival in the fastest molecular system

et al. 2006

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After preparing a coherent vibrational wave packet in the hydrogen molecular ion by ionizing neutral H 2 molecules with a 6.5 fs, 760 nm laser pulse at 3×10 14 W/cm 2 , we map its spatiotemporal evolution by the fragmentation induced with a second 6.5 fs laser pulse of doubled intensity. In this proof-of-principles experiment we visualize the oscillations of this most fundamental molecular system, observe a dephasing of the vibrational wave packet and its subsequent revival. Whereas the experimental data exhibit an overall qualitative agreement with the results of a simple numerical simulation, noticeable discrepancy is found in the characteristic revival time. The most likely reasons for this disagreement originate from the simplifications used in the theoretical model, which assumes a Franck-Condon transition induced by the pump pulse with subsequent field-free propagation of the H 2 + vibrational wave packet, and neglects the influence of the rotational motion.2

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Section: Methodsmentioning

confidence: 98%

“…This effect favors ionization at certain internuclear distances (4-5 a.u. for the case of H 2 + ) [41][42][43], in addition to the trivial R -dependence of the ionization potential, and is not taken into account in the simple tunneling model used in the calculation presented in Fig. 6b.…”

Section: Resultsmentioning

confidence: 99%

Real-time observation of vibrational revival in the fastest molecular system

et al. 2006

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“…CREI at the critical internuclear distance is a well established mechanism for strong-field double ionization of hydrogen by sufficiently long (>20 fs) near-IR laser pulses [1,2]. Whether a similar mechanism also operates during multiple ionization of larger molecules is still a matter of some debate.…”

Section: Synopsismentioning

confidence: 99%

“…We observe the dynamics of Coulomb explosion by comparing reconstructed CO 2 geometries for different Ti:Sapphire laser pulse durations (at the same intensity) ranging from few cycles (7 fs) to 200 fs. We conclude that for longer pulse durations (≥100 fs) Coulomb explosion proceeds through the enhanced ionization mechanism taking place at the critical O-O distance of 8 a.u., similarly to well known charge-resonance enhanced ionization (CREI) in H 2 .CREI at the critical internuclear distance is a well established mechanism for strong-field double ionization of hydrogen by sufficiently long (>20 fs) near-IR laser pulses [1,2]. Whether a similar mechanism also operates during multiple ionization of larger molecules is still a matter of some debate.…”

mentioning

confidence: 95%

Effects of laser pulse duration and intensity on Coulomb explosion of CO₂: Signatures of charge-resonance enhanced ionization

Litvinyuk

Bocharova

Sanderson

et al. 2009

J. Phys.: Conf. Ser.

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SynopsisWe studied laser-induced Coulomb explosion of CO 2 by full triple-coincidence momentum resolved detection of resulting ion fragments. From the coincidence momentum data we can reconstruct molecular geometry immediately before explosion. We observe the dynamics of Coulomb explosion by comparing reconstructed CO 2 geometries for different Ti:Sapphire laser pulse durations (at the same intensity) ranging from few cycles (7 fs) to 200 fs. We conclude that for longer pulse durations (≥100 fs) Coulomb explosion proceeds through the enhanced ionization mechanism taking place at the critical O-O distance of 8 a.u., similarly to well known charge-resonance enhanced ionization (CREI) in H 2 .CREI at the critical internuclear distance is a well established mechanism for strong-field double ionization of hydrogen by sufficiently long (>20 fs) near-IR laser pulses [1,2]. Whether a similar mechanism also operates during multiple ionization of larger molecules is still a matter of some debate. Here we present experimental evidence that multiple ionization of tri-atomic CO 2 molecules by intense femtosecond laser pulses can also proceed through enhanced ionization at a critical distance.The experiments were performed on the 5 kHz Ti:Sapphire beamline of the Advanced Laser Light Source (ALLS) at Varennes, Quebec. A hollow-core fiber compressor was used to produce 7 fs pulses. A supersonic jet of CO 2 molecules intersected a tightly focused laser beam inside a uniform-electric-field ion spectrometer equipped with a time-and positionsensitive delay-line anode detector. All resulting ion fragments were detected and their full 3D momentum vectors were determined.The triple coincidences of the type (O k+ , C l+ , O m+ ) characterized by a near-zero total momentum were identified as resulting from Coulomb explosion of a single molecule into a specific (k,l,m) channel: CO 2 → O k+ +C l+ +O m+ . For the (2,2,2) explosion channel we reconstructed the molecular structure, using an iterative procedure based on integration of the classical equations of motion for the fragments with pure Coulomb interactions.We compared the results for various pulse durations from 7 fs to 200 fs (Figure 1). The 7 fs pulses generated the most energetic fragments and reconstructed structures were nearly identical to that of a neutral CO 2 molecule. As the laser pulses become longer the kinetic energy decreases and the O-O distance increases due to the dynamics occurring before the explosion. For 100 fs pulses the O-O distance reaches 8 a.u., and it remains the same for longer pulses.We consider it a manifestation of the enhanced ionization process taking place in CO 2 molecular ions. However, the fragments in the (1,1,1) dissociation channel appear not to result from the enhanced ionization, pointing to the molecular trication CO 2 3+

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“…Indeed, in the presence of an external field, H 1 2 (or any other symmetrical molecular cation) has charge resonance states. [115,116] The transient dipole increases with distance and it is possible to stabilize the molecule at very large bond lengths. For the chosen parameters, the population in V 2 is $0:7 after the pump pulse, while the ionization and dissociation probabilities are both below 10%.…”

Section: The Role Of the Electronic Chargementioning

confidence: 99%

Molecular events in the light of strong fields: A light‐induced potential scenario

Chang

Solá

Shin

2016

Int J of Quantum Chemistry

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A new perspective on how to manipulate molecules by means of very strong laser pulses is emerging with insights from the so-called light-induced potentials, which are the adiabatic potential energy surfaces of molecules severely distorted by the effect of the strong field. Different effects appear depending on how the laser frequency is tuned, to a certain electronic transition, creating light-induced avoided crossings, or very off-resonant, generating Stark shifts. In the former case it is possible to induce dramatic changes in the geometry and redistribution of charges in the molecule while the lasers are acting and to fully control photodissociation reactions as well as other photochemical processes. Several theoretical proposals taken from the work of the authors are reviewed and analyzed showing the unique features that the strong-laser chemistry opens to control the transient properties and the dynamics of molecules.

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Charge-resonance-enhanced ionization of diatomic molecular ions by intense lasers

Cited by 801 publications

References 15 publications

Real-time observation of vibrational revival in the fastest molecular system

Real-time observation of vibrational revival in the fastest molecular system

Effects of laser pulse duration and intensity on Coulomb explosion of CO₂: Signatures of charge-resonance enhanced ionization

Molecular events in the light of strong fields: A light‐induced potential scenario

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Charge-resonance-enhanced ionization of diatomic molecular ions by intense lasers

Cited by 801 publications

References 15 publications

Real-time observation of vibrational revival in the fastest molecular system

Real-time observation of vibrational revival in the fastest molecular system

Effects of laser pulse duration and intensity on Coulomb explosion of CO2: Signatures of charge-resonance enhanced ionization

Molecular events in the light of strong fields: A light‐induced potential scenario

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Effects of laser pulse duration and intensity on Coulomb explosion of CO₂: Signatures of charge-resonance enhanced ionization