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Yokoyama, Keiichi; Matsuoka, Leo*
Ryoshi Woku No Shin Tenkai; Suri Kozo No Shinka To Oyo, p.228 - 242, 2019/08
Quantum walk is the quantum mechanical counter part of the classical random walk, which is known as mathematical model of diffusion process. By applying this new concept to light-matter interaction, a new isotope separation scheme is shown to be emerged. In addition, its advancements and forthcoming challenges are introduced.
Kobayashi, Takanori*; Matsuoka, Leo*; Yokoyama, Keiichi
Computational and Theoretical Chemistry, 1150, p.40 - 48, 2019/02
Times Cited Count:1 Percentile:2.04(Chemistry, Physical)One of important research targets in the development of cesium isotope separation system is design of recovery process of cesium atom. Relevant to this research target, the reaction cross section and reaction rate constant of a cesium exchange reaction through collision of the cesium iodide molecules with cesium atoms are calculated by a quasi-classical trajectory calculation based on a potential energy surface obtained by quantum chemistry calculations. Consequently, the rate constant is calculated to be 3.6 10 cmmolecules, as large as collision rate in the present condition. In addition, slightly positive temperature dependence is observed in the rate constant. This behavior is explained with the long-range attractive force and effect of subsequent dissociation process.
Kobayashi, Takanori*; Matsuoka, Leo*; Yokoyama, Keiichi
Nihon Enerugi Gakkai-Shi, 96(10), p.441 - 444, 2017/10
To investigate the reaction cross section of the cesium exchange reaction of CsI (v = 0, j = 0) + Cs Cs + ICs, we performed quasi-classical trajectory calculations on the potential energy surface calculated by the ab initio molecular orbital theory. The potential energy surface shows that intermediate CsI is formed without entrance barrier and has two equivalent Cs-I bonds. The reaction cross sections decrease monotonically with increasing collision energy. The rate constant k (v = 0, j = 0) was estimated to be about 310cm molecules at temperatures ranging from 500 to 1200K and a slight negative temperature dependence was observed.
Ichihara, Akira; Matsuoka, Leo*; Segawa, Etsuo*; Yokoyama, Keiichi
Physical Review A, 91(4), p.043404_1 - 043404_7, 2015/04
Times Cited Count:13 Percentile:58.58(Optics)We propose a new method for isotope-selective dissociation of diatomic molecules in the gas phase by using two kinds of terahertz-pulse fields. The first field consists of a train of pulses, which composes a frequency comb, excites the selected isotope into highly-rotationally excited state. The second intense pulse field dissociates the excited molecule by further rotational excitations. We performed wave-packet computations using the lithium chlorides LiCL and LiCl to demonstrate the applicability of our method. Nearly 20% of LiCl in the lowest rovibrational state is dissociated in the designed pulse fields, while the dissociation probability is negligible in LiCl. This method is expected to be applicable to other diatomic molecules, and to molecular ensembles whose rotational states spread in energy.
Ichihara, Akira; Matsuoka, Leo*; Kurosaki, Yuzuru; Yokoyama, Keiichi
Optical Review, 22(1), p.153 - 156, 2015/02
Times Cited Count:6 Percentile:34.43(Optics)We propose a method to excite the rovibrational states of diatomic molecules in the gas-phase isotope-selectively by optical pulses. In this method, the rotational state of the selected isotope molecule is excited by the terahertz frequency comb, and the vibrational state of high J molecule is excited via the fundamental transitions in the P-branch by using the second pulse. The applicability of the proposed method is demonstrated by computer simulations using the LiCl molecules in the thermal distribution at 70 K.
Yokoyama, Keiichi; Matsuoka, Leo*
Nihon Genshiryoku Gakkai-Shi ATOMO, 56(8), p.525 - 528, 2014/08
With respect to the isotope separation of cesium, one of the long-lived fission products, the background, principle, feasibility, and research activity in Kansai Photon Science Institute are described.
Ichihara, Akira; Matsuoka, Leo; Kurosaki, Yuzuru; Yokoyama, Keiichi
JPS Conference Proceedings (Internet), 1, p.013093_1 - 013093_4, 2014/03
Isotope-selective dissociation of the lithium chloride (LiCl) molecule was investigated by quantum mechanical calculations. LiCl in the initial rovibrational state (v=0,J=0) was excited by an optical frequency comb whose spectral frequencies were tuned to the rotational transition frequencies of LiCl. LiCl was not highly excited by the comb because of the difference of the transition frequencies. The time evolution of rovibrational population was evaluated using the close-coupling method during the comb irradiation. The dissociation process in the second pulse was calculated by the wave packet method. The amplitudes of close-coupling were employed as the input of the wave packet computation. The dissociation probability was estimated by absorbing wave packet using a damping function. By the optical pulses adopted, about 60% of LiCl was dissociated. The dissociation probability of LiCl was less than 2%t.
Ichihara, Akira; Matsuoka, Leo*; Kurosaki, Yuzuru; Yokoyama, Keiichi
Chinese Journal of Physics, 51(6), p.1230 - 1240, 2013/12
We derived an analytic expression for evaluating the transient rotational dynamics of diatomic molecules in an optical frequency comb which is tuned to induce a series of pure rotational transitions. The formulation is based on the quantum delta-kicked rotor model, and the orthogonality of delta functions at different time is assumed. The formulation is performed with the matrix decomposition technique. We derived the probability amplitude composed of term corresponding to a Bessel function of the first kind and other oscillating terms. The time dependence of obtained transition probability is shown as a staircase function.
Matsuoka, Leo; Yokoyama, Keiichi
Journal of Computational and Theoretical Nanoscience, 10(7), p.1617 - 1620, 2013/07
Times Cited Count:5 Percentile:25.2(Chemistry, Multidisciplinary)Matsuoka, Leo; Ogawa, Kenta*; Yokoyama, Keiichi
Proceedings of 10th Conference on Lasers and Electro-Optics Pacific Rim and 18th OptoElectronics and Communications Conference and Photonics in Switching 2013 (CLEO-PR & OECC/PS 2013) (USB Flash Drive), 2 Pages, 2013/06
Ichihara, Akira; Matsuoka, Leo; Kurosaki, Yuzuru; Yokoyama, Keiichi
Proceedings of 10th Conference on Lasers and Electro-Optics Pacific Rim and 18th OptoElectronics and Communications Conference and Photonics in Switching 2013 (CLEO-PR & OECC/PS 2013) (USB Flash Drive), 2 Pages, 2013/06
Computer simulations were performed for studying isotope-selective excitation of lithium chloride using a terahertz frequency comb. The time evolution of rovibrational population was calculated by the close-coupling method. The LiCl molecule was excited selectively in gaseous mixture of LiCl and LiCl by adjusting pulse parameters. Moreover, the wave packet calculations were performed to investigate the dissociation process. More than half of LiCl in the rovibrational state (v=0, J=150) were dissociated by the second pulse.
Matsuoka, Leo; Ichihara, Akira; Hashimoto, Masashi; Yokoyama, Keiichi
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 7 Pages, 2011/12
Matsuoka, Leo; Kasajima, Tatsuya; Hashimoto, Masashi; Yokoyama, Keiichi
Journal of the Korean Physical Society, 59(4), p.2897 - 2900, 2011/10
Times Cited Count:13 Percentile:62.2(Physics, Multidisciplinary)Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi
Proceedings of International Quantum Electronics Conference and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO Pacific Rim 2011) (CD-ROM), p.1363 - 1364, 2011/08
Matsuoka, Leo; Kasajima, Tatsuya; Hashimoto, Masashi; Yokoyama, Keiichi
arXiv.org (Internet), 5 Pages, 2011/04
Kasajima, Tatsuya; Yokoyama, Keiichi; Matsuoka, Leo; Yokoyama, Atsushi
Chemical Physics Letters, 485(1-3), p.45 - 48, 2010/01
Times Cited Count:1 Percentile:3.01(Chemistry, Physical)Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi
Physical Review A, 79(6), p.061404_1 - 061404_4, 2009/06
Times Cited Count:2 Percentile:14.72(Optics)Yokoyama, Keiichi; Matsuoka, Leo; Kasajima, Tatsuya; Tsubouchi, Masaaki; Yokoyama, Atsushi
Proceedings of 5th Asian Symposium on Intense Laser Science (ASILS-5), p.113 - 119, 2009/05
The current status of the fundamental research for the quantum control conducted at Kansai Photon Science Institute are reported. In particular, the experimental studies on vibrational control of diatomic molecules, the nitrogen molecules and the iodine molecules, and the theoretical study on the rotational control of the diatomic molecule, the cesium iodide molecule (CsI), are introduced. For the study of vibrational control of N, the vibration selective excitation with extremely broadband white light pulses is demonstrated by tuning the time interval of a linearly chirped white light pulse pair. For the study of vibrational control of I, the direction control of stimulated impulsive Raman transition is demonstrated by changing the sign of the chirp rate. For the study of rotational control of CsI, the isotope-selective population distribution transfer is demonstrated numerically using frequency comb in the terahertz-wave region.
Kurosaki, Yuzuru; Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi
Journal of Chemical Physics, 128(2), p.024301_1 - 024301_7, 2008/01
Times Cited Count:19 Percentile:56.02(Chemistry, Physical)Potential energy curves (PECs) for the ground and low-lying excited states of the cesium iodide (CsI) molecule have been calculated using the MRSDCI method. PECs for 7 -S states were first calculated and then those for 13 states including spin-orbit coupling were obtained. Spectroscopic constants for the calculated ground 0-state PEC were found to agree well with experiment. Transition dipole moments (TDMs) between 0 and the other states were also obtained and TDM between 0 and 0 was predicted to be the largest and that between 0 and 0 was the second largest around the equilibrium internuclear distance. Finally, vibrational levels of the 0 PEC for the two isotopic analogs, CsI and CsI, were numerically obtained and it was found that the = 136 state of CsI or CsI is most isolated from any adjacent vibrational level.
Yokoyama, Keiichi; Sugita, Akihiro; Teranishi, Yoshiaki*; Itakura, Ryuji; Matsuoka, Leo; Yokoyama, Atsushi
no journal, ,
State-selective excitation of atomic cesium and potassium to their spin-orbit states, Cs(7D-6S) and K(4P-4S), are carried out by a coherent quantum control technique. In the weak field regime, ultrafast and highly selective excitation of cesium atoms has been successfully demonstrated with a pair of identical transform-limited pulses in which the control parameter is the phase difference between the two pulses alone. However, the excitation probability is very small (0.001) due to the weak laser field. To perform the selective excitation with large excitation probability (1), one-photon process of the K(4P-4S) transition is examined. The excitation probability is expected to become large while the selectivity degrades if the control parameter is the phase difference alone. The obtained laser intensity dependence agrees well with the theoretical prediction, indicating the excitation indeed in the non-perturbative regime.