A Quasiclassical trajectory calculation to compute the reaction cross section and thermal rate constant for the cesium exchange reaction CsI + Cs Cs + ICs

Kobayashi, Takanori*; Matsuoka, Leo*; Yokoyama, Keiichi

Computational and Theoretical Chemistry, 1150, p.40 - 48, 2019/02

https://doi.org/10.1016/j.comptc.2019.01.008

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.

Isotope-selective dissociation of diatomic molecules by terahertz optical pulses

Ichihara, Akira; Matsuoka, Leo*; Segawa, Etsuo*; Yokoyama, Keiichi

Physical Review A, 91(4), p.043404_1 - 043404_7, 2015/04

https://doi.org/10.1103/PhysRevA.91.043404

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.

Optical frequency comb opens up highly efficient isotope separation of long-lived fission products; The Quantum walk to reduce radioactive waste

Yokoyama, Keiichi; Matsuoka, Leo*

Nihon Genshiryoku Gakkai-Shi ATOMO, 56(8), p.525 - 528, 2014/08

https://doi.org/10.3327/jaesjb.56.8_525

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.

An Analytic formula for describing the transient rotational dynamics of diatomic molecules in an optical frequency comb

Ichihara, Akira; Matsuoka, Leo*; Kurosaki, Yuzuru; Yokoyama, Keiichi

Chinese Journal of Physics, 51(6), p.1230 - 1240, 2013/12

https://doi.org/10.6122/CJP.51.1230

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.

Spectral measurement of picosecond optical pulses by optogalvanic spectroscopy

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

Theoretical study for laser isotope separation of heavy-element molecules in a thermal distribution

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

Narrow-band regenerative amplifier for momentum imaging spectroscopy of molecules

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

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6193760

Vibration-selective coherent anti-Stokes Raman scattering with linearly chirped white-light pulses

Kasajima, Tatsuya; Yokoyama, Keiichi; Matsuoka, Leo; Yokoyama, Atsushi

Chemical Physics Letters, 485(1-3), p.45 - 48, 2010/01

https://doi.org/10.1016/j.cplett.2009.12.032

Quantum control of molecular vibration and rotation toward the isotope separation

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.

State-selective excitation of alkali-metal atoms by the phase control in the strong laser field

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.