International workshop on theory for attosecond quantum dynamics (IWTAQD) 31



May 21-23 , 2026
 The workshop is open to everyone


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Participants
Stefanos Carlström
 		Max Born Inst
 Attosecond Physics theory
Takeshi Sato
 		U Tokyo Quantum Chemistry
Akiyoshi Hishikawa Nagoya U
 Co-Chair, FEL, Molecular dynamics
Mizuho Fushitani Nagoya U Strong field exp
Akitaka Matsuda Nagoya U Strong field exp
Yuki Ono Nagoya U Strong field exp
Runa Kuroda Nagoya U Strong field exp
Hiroshi Kinoshita Nagoya U Strong field exp
Kyoichiro Yasui Nagoya U Strong field exp
Riku Nakayama Nagoya U Strong field exp
Tomoki Nishikawara Nagoya U Strong field exp
Kazumi Ogawa Nagoya U Strong field exp
Ryogo Otagi Nagoya U Strong field exp
Ryunosuke Kasai Nagoya U Strong field exp
Takumu Matsumiya Nagoya U Strong field exp
Sota Matsumiya Nagoya U Strong field exp
Yugo Ano Nagoya U Strong field exp
Risa Sugiura Nagoya U Strong field exp
Hana Hamada Nagoya U Strong field exp
Dimitrii Riazantcev Nagoya U Strong field exp




Hiroka Hasegawa UEC
 Molecular dissociation
Toru Morishita UEC
 Chair



Seminar Program (tentative)

May 21 (Thr) 2026
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    FREE DISCUSSION
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May 22  (Fri) 2026
Venue: Chemistry gallery (Nagoya U)
The venue is Chemistry Gallery, located on the second floor of Research Center for Materials Science, Nagoya University. The building is D2-10 on the Higashiyama Campus map:
https://en.nagoya-u.ac.jp/extra/map/

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13:00-13:30 FREE DISCUSSION
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13:30-14:10  Stefanos Carlström (Max Born Inst)
"Ultrafast Spin Migration in the Argon Dimer Cation"
Abstract:
Upon sudden removal of an electron from a neutral molecule, the remaining electrons do not have time to relax, and a non-stationary electronic wavepacket is formed, resulting in a quasi-periodic oscillatory motion commonly referred to as charge migration [1, 2]. In the presence of spin–orbit interaction, the electronic motion must necessarily also involve spatio-temporal dependence of the spin density; correspondingly, we term this phenomenon spin migration.

Of vital importance to the electronic coherence, is the correlated motion of the nuclei. Unless there is spatial overlap of the nuclear wavefunctions correlated with different electronic states, coherence between the electronic states does not lead to observable interference patterns [3], severely diminishing or even precluding the measurement of charge migration. However, we find that the same does not apply to spin migration. On the contrary, the motion of the nuclear wavepacket can be also be used to drive the electronic coherences, and hence the spin migration. Furthermore, whereas the nuclear motion is detrimental to ordinary charge migration, due to the long-range Coulomb interaction, spin migration is remarkably robust to the nuclear motion, and persists over long time. This fact may possibly be utilized to control chemical reactivity; by tailoring the spin density of the cation, we can steer the molecular fragmentation into a pathway of our choosing.

As model system, we choose to study the argon dimer cation, where the separation of vibronic states are comparable to the spin–orbit splitting in the argon atoms at infinite separation. Hence, even a simple linear combination of a few vibronic eigenstates can be expected to induce non-trivial spatio–temporal dependence of the spin density, on multiple time scales simultaneously. In particular, we find that the spin migrates between the two atoms of the dimer within 10 fs, and this motion persists up to 1000 fs, while being driven by complex interplay of electronic and nuclear degrees of freedom.

References
    J Breidbach & L S Cederbaum The Journal of Chemical Physics, 118(9), 3983–3996. (2003).
    A I Kuleff et al. The Journal of Chemical Physics, 123(4), 044111. (2005).
    M Ruberti et al. Physical Chemistry Chemical Physics, 24(33), 19673–19686. (2022).

14:10-14:50 Hiroka Hasegawa (UEC)
"Post-ionization effect in rescattering-induced Coulomb explosion of methane in intense laser fields "
Abstract:
Kinetic energy release (KER) spectra of rescattering-induced Coulomb explosion of CH4 in intense laser fields are calculated under the adiabatic approximation. In this presentation, we will discuss the post-ionization effect from the KER spectra structures which are different from those of dissociation in field-free conditions.

14:50-15:10 Runa Kuroda (Nagoya U)
"Photoelectron circular dichroism of oxirane derivatives in intense laser fields studied by electron-ion coincidence momentum imaging. "
Abstract:
Photoelectron circular dichroism (PECD) of (S)-methyloxirane (C3H6O) and (S) epichlorohydrin (C3H5OCl) in tunnel ionization regime is investigated by electron-ion coincidence momentum imaging. The transverse momentum distributions show a clear asymmetry between the forward and backward components along the laser propagation direction, or PECD. A theoretical calculation based on a tunnel ionization theory suggests that tunnel PECD reflect the molecular orbital character.

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15:10-15:30 FREE DISCUSSION
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15:30-16:10 Takeshi Sato (U Tokyo)
"TBA"
Abstract:

16:10-16:50 Toru Morishita and Shinji Ito (UEC)
"High-order harmonic generation in one-dimensional molecule using quantum theory of radiation"
Abstract:
We performed calculations of HHG based on the quantum theory of radiations for  a one-dimensional diatomic molecule with finite-width Gaussian potentials. In this presentation, we will discuss details such as the dependence of HHG yields on incident laser intensity as well as the roles of excited and continuum states of the targets, comparing results from the classical and quantum theories of radiation.

16:50-17:10 Akitaka Matsuda (Nagoya U)
"Femtosecond laser filament reaction in gaseous hexane studied by velocity screening time-of-flight mass spectrometry"
Abstract :
Femtosecond laser filament induced association reactions in gaseous hexane are studied by time-of-flight mass spectrometry. Velocity screening allowed unambiguous determination of neutral filament products discriminating species produced by ionization in mass analysis.

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17:10- FREE DISCUSSION
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May 23  (Sat) 2026
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    FREE DISCUSSION
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Toru Morishita,UEC