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Abstract
Above-threshold ionization of atoms in strong laser fields is extensively studied for its overwhelming importance and universality. However, its counterpart, above-threshold dissociation of molecules in strong laser fields, is hard to be observed, although it has been predicted for decades. In this paper, by measuring the momenta of photoelectron and dissociative fragments coincidently, we successfully obtained distinct nuclear energy peaks of the high-order above-threshold dissociation, which must appear simultaneously with the above-threshold ionization. The coexistence of high-order above-threshold dissociation and high-order above-threshold ionization in molecular dissociative ionization offers a perspective to disentangle the complex electron–nuclear correlation in molecules and to image the molecular orbitals, and so on. Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.
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Shu CC, Dong D, Yuan KJ. Single-laser-induced quantum interference in photofragmentation reaction of D + 2. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1297861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Chuan-Cun Shu
- School of Engineering and Information Technology, University of New South Wales , Canberra, ACT, Australia
| | - Daoyi Dong
- School of Engineering and Information Technology, University of New South Wales , Canberra, ACT, Australia
| | - Kai-Jun Yuan
- School of Engineering and Information Technology, University of New South Wales , Canberra, ACT, Australia
- Laboratoire de Chimie Théorique, Faculté des Sciences, Université de Sherbrooke , Sherbrooke, Canada
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Dissociation and Ionization of Quasi-Periodically Vibrating H 2+ in Intense Few-Cycle Mid-Infrared Laser Fields. Sci Rep 2017; 7:42086. [PMID: 28165034 PMCID: PMC5292692 DOI: 10.1038/srep42086] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 01/05/2017] [Indexed: 01/12/2023] Open
Abstract
Using quantum mechanics calculations, we theoretically study the dissociation and ionization dynamics of the hydrogen-molecule ion in strong laser fields. Having prepared the nuclear wave packet of H2+ in a specific vibrational state, a pump laser is used to produce a vibrational excitation, leading to quasi-periodical vibration without ionization. Then, a time-delayed few-cycle laser is applied to trigger the dissociation or ionization of H2+. Both the time delay and the intensity of the probe laser alter the competition between dissociation and ionization. We also explore the dependence of kinetic-energy release spectra of fragments on the time delay, showing that the channels of above-threshold dissociation and below-threshold dissociation are opened and closed periodically. Also, dissociation from different channels is influenced by nuclear motion. The dissociation mechanism has been described in detail using the Floquet picture. This work provides a useful method for steering the electronic and nuclear dynamics of diatomic molecules in intense laser fields.
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Shu CC, Yuan KJ, Dong D, Petersen IR, Bandrauk AD. Identifying Strong-Field Effects in Indirect Photofragmentation Reactions. J Phys Chem Lett 2017; 8:1-6. [PMID: 28052679 DOI: 10.1021/acs.jpclett.6b02613] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Exploring molecular breakup processes induced by light-matter interactions has both fundamental and practical implications. However, it remains a challenge to elucidate the underlying reaction mechanism in the strong field regime, where the potentials of the reactant are modified dramatically. Here we perform a theoretical analysis combined with a time-dependent wavepacket calculation to show how a strong ultrafast laser field affects the photofragment products. As an example, we examine the photochemical reaction of breaking up the molecule NaI into the neutral atoms Na and I, which due to inherent nonadiabatic couplings are indirectly formed in a stepwise fashion via the reaction intermediate NaI*. By analyzing the angular dependencies of fragment distributions, we are able to identify the reaction intermediate NaI* from the weak to the strong field-induced nonadiabatic regimes. Furthermore, the energy levels of NaI* can be extracted from the quantum interference patterns of the transient photofragment momentum distribution.
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Affiliation(s)
- Chuan-Cun Shu
- School of Engineering and Information Technology, University of New South Wales , Canberra, Australian Capital Territory 2600, Australia
| | - Kai-Jun Yuan
- School of Engineering and Information Technology, University of New South Wales , Canberra, Australian Capital Territory 2600, Australia
- Laboratoire de Chimie Théorique, Faculté des Sciences, Université de Sherbrooke Sherbrooke, Québec J1K 2R1, Canada
| | - Daoyi Dong
- School of Engineering and Information Technology, University of New South Wales , Canberra, Australian Capital Territory 2600, Australia
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Ian R Petersen
- School of Engineering and Information Technology, University of New South Wales , Canberra, Australian Capital Territory 2600, Australia
| | - Andre D Bandrauk
- Laboratoire de Chimie Théorique, Faculté des Sciences, Université de Sherbrooke Sherbrooke, Québec J1K 2R1, Canada
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Qin C, Zhai H, Zhang X, Liu Y. Coherent Control of Autler-Townes Splitting in Photoelectron Spectroscopy: The Effect of Laser Intensity and Laser Envelope. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.11.3294] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Zhang J, He GQ, He F. Optimal laser pulse design for transferring the coherent nuclear wave packet of H +2. Mol Phys 2014. [DOI: 10.1080/00268976.2013.874601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Su Q, Han Y, Cong SL. Quantum control of multi-photon dissociation of HCl+ with intense femtosecond laser pulses. J Chem Phys 2013; 138:024304. [DOI: 10.1063/1.4773022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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SU QIANZHEN, YU JIE, YUAN KAIJUN, CONG SHULIN. CONTROLLING ABOVE-THRESHOLD DISSOCIATION BRANCHING RATIOS OF HD+ WITH FEMTOSECOND LASER PULSE TRAIN. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2012. [DOI: 10.1142/s0219633612500472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Above-threshold dissociation (ATD) process of the molecular ions HD+ steered by a femtosecond laser pulse train (LPT) is investigated theoretically using the time-dependent quantum wave packet method. Energy-dependent distributions of ATD fragments are analyzed by using an asymptotic-flow expression in the momentum space. It is found that fragment kinetic energy spectra shift to low energy region with increasing pulse number of LPT. The photofragment branching ratio between the 1sσg and 2pσu dissociation channels is sensitive to the pulse number of LPT. The momentum distribution of the ATD fragments is discussed in detail.
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Affiliation(s)
- QIAN-ZHEN SU
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, P. R. China
| | - JIE YU
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, P. R. China
| | - KAI-JUN YUAN
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, P. R. China
| | - SHU-LIN CONG
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, P. R. China
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YUAN KAIJUN, LIU ZHENGTANG, YU JIE, CHEN MAODU, CONG SHULIN. THEORETICAL STUDY OF ABOVE THRESHOLD DISSOCIATION OF HD+ IN FEMTOSECOND LASER FIELDS. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s0219633609005416] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The above threshold dissociation (ATD) of the HD+ molecular ion in a linearly polarized femtosecond laser field is theoretically studied using three-dimensional time-dependent quantum wave packet method. Based on the Born–Oppenheimer approximation (BOA), calculations are performed on two electronic states, the ground state 1sσ and the excited state 2pσ. The energy-dependent distributions of the dissociated fragments, resulting from the ATD, are calculated by using an asymptotic-flow expression in the momentum space. The numerical results demonstrate that, in the laser field of wavelength λ = 800 nm and full-width at half-maximum (FWHM) τ = 30 fs , only two-photon dissociation is observable at a weaker pulse peak intensity, 5.0 × 1012 W cm -2, while at an intense intensity, 1.5 × 1015 W cm -2, the dissociated fragments resulting from four-photon absorption dominates over the photodissociation process. These results are consistent with the experimental observation of Orr et al. [Orr PA et al., Phys Rev Lett98:163001, 2007]. The ac Stark-shift caused by intense laser field will change the kinetic energies of the fragments. The ATD phenomena are quantitatively interpreted in terms of the concept of light-induced potential. The molecular rotation and alignment have some effects on the kinetic energy spectrum of the dissociated fragments. The molecular rotation reduces the ac Stark-shift and broadens the peaks of kinetic energy spectra of the dissociated fragments. However, the intense laser field can effectively align the molecule and is helpful to increase the ATD probability. The ATD spectrum is related to the initial quantum numbers J0 and M0 of the molecule. The ATD spectrum of HD+ is calculated at a limited thermal temperature.
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Affiliation(s)
- KAI-JUN YUAN
- Department of Physics, Dalian University of Technology, Dalian 116024, China
| | - ZHENG-TANG LIU
- Department of Physics, Dalian University of Technology, Dalian 116024, China
| | - JIE YU
- Department of Physics, Dalian University of Technology, Dalian 116024, China
| | - MAO-DU CHEN
- Department of Physics, Dalian University of Technology, Dalian 116024, China
| | - SHU-LIN CONG
- Department of Physics, Dalian University of Technology, Dalian 116024, China
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Bernard J, Montagne G, Brédy R, Terpend-Ordacière B, Bourgey A, Kerleroux M, Chen L, Schmidt HT, Cederquist H, Martin S. A "tabletop" electrostatic ion storage ring: Mini-Ring. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:075109. [PMID: 18681736 DOI: 10.1063/1.2957609] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report on the design, construction, and commissioning of a novel electrostatic ion storage ring of small dimensions--in the following referred to as "Mini-Ring." Mini-Ring consists of four horizontal parallel-plate deflectors and two conical electrostatic mirrors. Ions are injected through the two deflectors on the injection side and off axis with respect to the conical mirrors which face each other. The first injection deflector, originally at zero voltage, is switched to its set value such that the ions after one turn follow stable trajectories of lengths of roughly 30 cm. This design reduces the number of electrodes necessary to guide the ion beam through the ring in stable orbits. The six elements (deflectors and mirrors) are placed on a common grounded plate--the tabletop. Here, we present the design, ion trajectory simulations, and results of the first test experiments demonstrating the successful room-temperature operation of Mini-Ring at background pressures of 10(-6) - 10(-7) mbar.
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Affiliation(s)
- J Bernard
- Universite Lyon 1, CNRS, LASIM UMR 5579, bât. A. Kastler, 43 Bvd. du 11 novembre 1918, F-69622 Villeurbanne, France
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McKenna J, Sayler AM, Anis F, Gaire B, Johnson NG, Parke E, Hua JJ, Mashiko H, Nakamura CM, Moon E, Chang Z, Carnes KD, Esry BD, Ben-Itzhak I. Enhancing high-order above-threshold dissociation of H2+ beams with few-cycle laser pulses. PHYSICAL REVIEW LETTERS 2008; 100:133001. [PMID: 18517942 DOI: 10.1103/physrevlett.100.133001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Indexed: 05/26/2023]
Abstract
High-order (three-photon or more) above-threshold dissociation (ATD) of H(2)(+) has generally not been observed using 800 nm light. We demonstrate a strong enhancement of its probability using intense 7 fs laser pulses interacting with beams of H(2)(+), HD(+), and D(2)(+) ions. The mechanism invokes a dynamic control of the dissociation pathway. These measurements are supported by theory that additionally reveals, for the first time, an unexpectedly large contribution to ATD from highly excited electronic states.
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Affiliation(s)
- J McKenna
- J.R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas 66506, USA
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