1
|
Biró L, Csehi A. Attosecond Probing of Nuclear Vibrations in the D 2+ and HeH + Molecular Ions. J Phys Chem A 2024; 128:858-867. [PMID: 38277484 DOI: 10.1021/acs.jpca.3c07031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
We study the ultrafast photodissociation of small diatomic molecules using attosecond laser pulses of moderate intensity in the (extreme) ultraviolet regime. The simultaneous application of subfemtosecond laser pulses with different photon energies─resonant in the region of the molecular motion─allows one to monitor the vibrational dynamics of simple diatomics, like the D2+ and HeH+ molecular ions. In our real-time wave packet simulations, the nuclear dynamics is initiated either by sudden ionization (D2+) or by explicit pump pulses (HeH+) via distortion of the potential energy of the molecule. The application of time-delayed attosecond pulses leads to the breakup of the molecules, and the information on the underlying bound-state dynamics is imprinted in the kinetic energy release (KER) spectra of the outgoing fragments. We show that the KER-delay spectrograms generated in our ultrafast pump-probe schemes are able to reconstruct the most important features of the molecular motion within a given electronic state, such as the time period or amplitude of oscillations, interference patterns, or the revival and splitting of the nuclear wave packet. The impact of probe pulse duration, which is key to the applicability of the presented mapping scheme, is investigated in detail.
Collapse
Affiliation(s)
- László Biró
- Department of Theoretical Physics, Faculty of Science and Technology, University of Debrecen, H-4002 Debrecen, P.O. Box 400, Hungary
| | - András Csehi
- Department of Theoretical Physics, Faculty of Science and Technology, University of Debrecen, H-4002 Debrecen, P.O. Box 400, Hungary
| |
Collapse
|
2
|
Biró L, Csehi A. Tracing the vibrational dynamics of sodium iodide via the spectrum of emitted photofragments. Phys Chem Chem Phys 2022; 24:13234-13244. [PMID: 35603791 DOI: 10.1039/d2cp00901c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We study by real-time wave packet simulations the ultrafast photodissociation dynamics of the sodium iodide molecule with the aim to trace molecular vibrational motion in a bound electronic state. Applying a few-cycle infrared pump laser pulse, a nuclear wave packet is created in the ground electronic state via the dynamic Stark shift of the potential energy curves of the molecule. To probe this coherent motion in the ground state, we propose to use a series of ultrashort laser pulses with different photon energies that resonantly promote the spread-out wave packet to the repulsive excited state. As the kinetic energy release (KER) spectrum of the dissociating photofragments is sensitive to the shape of the vibrational wave packet, in our pump-probe scheme, KER-delay spectrograms generated for different probe photon energies are used to monitor the molecular motion in the bound state. In our numerical analysis supported by a simple analytical model, we show that for sufficiently long probe pulses the proposed mapping scheme reaches its limits as nuclear wave packet interferences wash out the observed images. The appearance of these interferences is attributed to nuclear wave packet amplitudes that are generated at the first and second half of the probe pulse with the same energy but with a certain time delay. In our detailed numerical survey on the laser parameter dependence of the presented scheme, we find that resonant probe pulses with a few femtosecond duration are suitable for a qualitative mapping of the bound-state molecular motion.
Collapse
Affiliation(s)
- László Biró
- Department of Theoretical Physics, Faculty of Science and Technology, University of Debrecen, PO Box 400, H-4002 Debrecen, Hungary.
| | - András Csehi
- Department of Theoretical Physics, Faculty of Science and Technology, University of Debrecen, PO Box 400, H-4002 Debrecen, Hungary.
| |
Collapse
|
3
|
Nabekawa Y, Furukawa Y, Okino T, Amani Eilanlou A, Takahashi EJ, Yamanouchi K, Midorikawa K. Sub-10-fs control of dissociation pathways in the hydrogen molecular ion with a few-pulse attosecond pulse train. Nat Commun 2016; 7:12835. [PMID: 27647423 PMCID: PMC5494193 DOI: 10.1038/ncomms12835] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 08/05/2016] [Indexed: 11/24/2022] Open
Abstract
The control of the electronic states of a hydrogen molecular ion by photoexcitation is considerably difficult because it requires multiple sub-10 fs light pulses in the extreme ultraviolet (XUV) wavelength region with a sufficiently high intensity. Here, we demonstrate the control of the dissociation pathway originating from the 2pσu electronic state against that originating from the 2pπu electronic state in a hydrogen molecular ion by using a pair of attosecond pulse trains in the XUV wavelength region with a train-envelope duration of ∼4 fs. The switching time from the peak to the valley in the oscillation caused by the vibrational wavepacket motion in the 1sσg ground electronic state is only 8 fs. This result can be classified as the fastest control, to the best of our knowledge, of a molecular reaction in the simplest molecule on the basis of the XUV-pump and XUV-probe scheme.
Collapse
Affiliation(s)
- Yasuo Nabekawa
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Yusuke Furukawa
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- Present address: Department of Engineering Science, the University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Tomoya Okino
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - A Amani Eilanlou
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Eiji J. Takahashi
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Kaoru Yamanouchi
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- Department of Chemistry, School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Katsumi Midorikawa
- Attosecond Science Research Team, Extreme Photonics Research Group, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| |
Collapse
|
4
|
Rosenthal N, Marcus G. Discriminating between the Role of Phase Matching and that of the Single-Atom Response in Resonance Plasma-Plume High-Order Harmonic Generation. PHYSICAL REVIEW LETTERS 2015; 115:133901. [PMID: 26451557 DOI: 10.1103/physrevlett.115.133901] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Indexed: 06/05/2023]
Abstract
Resonance enhancement of high-order harmonic generation has recently been found in the interaction of intense ultrashort laser pulses with laser ablated plasma plumes. It is a promising route towards the production of an intense and coherent extreme ultraviolet radiation source. However, the mechanism of this resonance enhancement is still not clear. There are two possible explanations; one relies on a better recombination cross section through an autoionization state in the single-atom response. The other relies on improved phase matching conditions around the resonance. Here, we try to discriminate between these two conjectures by measuring coherence lengths of the harmonics, both on resonance and off resonance. Our findings support the single-atom response hypothesis.
Collapse
Affiliation(s)
- Noa Rosenthal
- Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gilad Marcus
- Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| |
Collapse
|
5
|
Nabekawa Y, Furukawa Y, Okino T, Amani Eilanlou A, Takahashi EJ, Yamanouchi K, Midorikawa K. Settling time of a vibrational wavepacket in ionization. Nat Commun 2015; 6:8197. [PMID: 26324319 PMCID: PMC4569855 DOI: 10.1038/ncomms9197] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/28/2015] [Indexed: 11/20/2022] Open
Abstract
The vibrational wavepacket of a diatomic molecular ion at the time of ionization is usually considered to be generated on the basis of the Franck–Condon principle. According to this principle, the amplitude of each vibrational wavefunction in the wavepacket is given by the overlap integral between each vibrational wavefunction and the ground vibrational wavefunction in the neutral molecule, and hence, the amplitude should be a real number, or equivalently, a complex number the phase of which is equal to zero. Here we report the observation of a non-trivial phase modulation of the amplitudes of vibrational wavefunctions in a wavepacket generated in the ground electronic state of a molecular ion at the time of ionization. The phase modulation results in a group delay of the specific vibrational states of order 1 fs, which can be regarded as the settling time required to compose the initial vibrational wavepacket. Instantaneous generation of a vibrational wavepacket in a molecular ion is usually assumed in an ionization process. Here, by means of frequency-resolved optical gating, the authors observe a non-trivial phase modulation in a H2+ molecule, which is interpreted as a ∼1-fs settling time.
Collapse
Affiliation(s)
- Yasuo Nabekawa
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Yusuke Furukawa
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Tomoya Okino
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - A Amani Eilanlou
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Eiji J Takahashi
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Kaoru Yamanouchi
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Katsumi Midorikawa
- Attosecond Science Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| |
Collapse
|