Hiroka Hasegawa
| Department of Engineering Science | Assistant Professor |
| Cluster III (Fundamental Science and Engineering) | Assistant Professor |
Researcher Information
Research Activity Information
Paper
- Dissociative ionization and Coulomb explosion of CH4 in two-color asymmetric intense laser fields
H. Hasegawa; A. Matsuda; T. Morishita; L. B. Madsen; F. Jensen; O. I. Tolstikhin; A. Hishikawa
Lead, Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), 25, 37, 25408-25419, Sep. 2023, Peer-reviwed, Three-dimensional ion momentum imaging reveals that methane in two-color asymmetric intense laser fields has different waveform dependence for atomic and molecular hydrogen ion ejection.
Scientific journal - Helicity-dependent dissociative tunneling ionization of CF4 in multicycle circularly polarized intense laser fields
H. Fujise; M. Uemura; H. Hasegawa; D. Ikeya; A. Matsuda; T. Morishita; L. B. Madsen; F. Jensen; O. I. Tolstikhin; A. Hishikawa
Physical Chemistry Chemical Physics, Royal Society of Chemistry ({RSC}), 24, 15, 8962-8969, Apr. 2022, Peer-reviwed
Scientific journal - Asymmetric Dissociative Tunneling Ionization of Tetrafluoromethane in omega-2 omega Intense Laser Fields
Hiroka Hasegawa; Tiffany Walmsley; Akitaka Matsuda; Toru Morishita; Lars Bojer Madsen; Frank Jensen; Oleg I. Tolstikhin; Akiyoshi Hishikawa
Lead, FRONTIERS IN CHEMISTRY, FRONTIERS MEDIA SA, 10, Apr. 2022, Peer-reviwed, Dissociative ionization of tetrafluoromethane (CF4) in linearly polarized omega-2 omega ultrashort intense laser fields (1.4 x 10(14) W/cm(2), 800 and 400 nm) has been investigated by three-dimensional momentum ion imaging. The spatial distribution of CF3+ produced by CF4 -> CF3++ F + e(-) exhibited a clear asymmetry with respect to the laser polarization direction. The degree of the asymmetry varies by the relative phase of the omega and 2 omega laser fields, showing that 1) the breaking of the four equivalent C-F bonds can be manipulated by the laser pulse shape and 2) the C-F bond directed along the larger amplitude side of the omega-2 omega electric fields tends to be broken. Weak-field asymptotic theory (WFAT) shows that the tunneling ionization from the 4t (2) second highest-occupied molecular orbital (HOMO-1) surpasses that from the 1t (1) HOMO. This predicts the enhancement of the tunneling ionization with electric fields pointing from F to C, in the direction opposite to that observed for the asymmetric fragment ejection. Possible mechanisms involved in the asymmetric dissociative ionization, such as post-ionization interactions, are discussed.
Scientific journal, English - Time-resolved shot-by-shot photoelectron spectroscopy of autoionizing Xe+ states by EUV–free-electron-laser and near-IR laser pulses
Mizuho Fushitani; Yoshitaka Kawabe; Hikaru Fujise; Makoto Yamada; Hiroka Hasegawa; Shigeki Owada; Tadashi Togashi; Kyo Nakajima; Makina Yabashi; Akitaka Matsuda; Yasumasa Hikosaka; Akiyoshi Hishikawa
Physical Review A, American Physical Society ({APS}), 104, 2, 06 Aug. 2021, Peer-reviwed
Scientific journal - Angle dependence of dissociative tunneling ionization of NO in asymmetric two-color intense laser fields
Tomoyuki Endo; Hikaru Fujise; Hiroka Hasegawa; Akitaka Matsuda; Mizuho Fushitani; Oleg Tolstikhin; Toru Morishita; Akiyoshi Hishikawa
PHYSICAL REVIEW A, AMER PHYSICAL SOC, 100, 5, Nov. 2019, Peer-reviwed, Dissociative tunneling ionization of nitric oxide (NO) in linearly polarized phase-locked two-color femtosecond intense laser fields (45 fs, lambda = 800 and 400 nm, total field intensity I = 1 x 10(14) W/cm(2)) has been studied by three-dimensional ion momentum imaging. The N+ fragment produced by the dissociative ionization, NO -> NO+ e(-) -> N+ + O + e(-), exhibits a butterflylike momentum distribution peaked at finite angles with respect to the laser polarization direction. In addition, a clear dependence on the relative phase between the two laser fields is observed, showing that the tunneling ionization occurs efficiently when the electric field points from N to O. For the highest kinetic energy component, the observed orientation dependence is well explained with theoretical calculations by the weak-field asymptotic theory for the 2 pi highest occupied molecular orbital (HOMO). On the other hand, the peak angle shifts toward the laser polarization direction as the kinetic energy decreases, indicating that pathways other than direct ionization from the HOMO contribute to the dissociative ionization.
Scientific journal, English
MISC
- Selective-bond breaking of CF4 in phase-locked ω-2ω intense laser fields
Hiroka Hasegawa; Tiffany Walmsley; Akitaka Matsuda; Toru Morishita; Lars Bojer Madsen; Frank Jensen; Oleg I. Tolstikhin; Akiyoshi Hishikawa
Lead, To extend application of ω-2ω intense field reaction control to highly symmetric molecules, CF4 was studied by three-dimensional momentum imaging. The C-F bond directed along larger side of the laser fields tends to be broken., Optica Publishing Group, Jul. 2022, The International Conference on Ultrafast Phenomena (UP) 2022, Peer-reviwed
Books and other publications
Lectures, oral presentations, etc.
- Calculation of dissociative ionization of molecules in intense laser fields
Hiroka Hasegawa
Invited oral presentation, English, 29th International Workshop on Theory for Attsecond Quantum Dynamics, Invited
04 Feb. 2025
03 Feb. 2025- 05 Feb. 2025 - Orientation dependent tunneling ionization and dissociation of methane in asymmetric two-color intense laser fields
Hiroka Hasegawa
Invited oral presentation, English, 15th Asian International Seminar on Atomic and Molecular Physics (AISAMP15), Invited
22 Aug. 2024
19 Aug. 2024- 23 Aug. 2024 - 位相制御ω-2ω強レーザー場におけるCH4の解離性イオン化過程とクーロン爆発過程
長谷川景郁; 松田晃孝; 森下亨; Lars Bojer Madsen; Frank Jensen; Oleg I. Tolstikhin; 菱川明栄
Oral presentation, 第78回 日本物理学会 年次大会
17 Sep. 2023
