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Journal Articles

Quantum optimal control of rovibrational excitations of a diatomic alkali halide; One-photon vs. two-photon processes

Kurosaki, Yuzuru*; Yokoyama, Keiichi

Universe (Internet), 5(5), p.109_1 - 109_15, 2019/05

 Times Cited Count:0 Percentile:100(Astronomy & Astrophysics)

Regarding rovibrational transitions of diatomic alkali haride molecules, optimal waveform of laser electric field was calculated on the basis of the optimal control theory. In this study, we implemented the polarizability term into the Hamiltonian, which defines the field-molecule interaction. As a result, we obtained waveforms causing both one- and two-photon processes in a relatively high electric field regime, while waveforms causing only one-photon process was observed in a weak filed regime as well as the previous study. These results imply that the effect of two-photon process is successfully taken into account in the optimal control theory calculation. Now we can expect more reliable calculation even for strong laser field.

Journal Articles

Quantum optimal control of the isotope-selective rovibrational excitation of diatomic molecules

Kurosaki, Yuzuru*; Yokoyama, Keiichi

Chemical Physics, 493, p.183 - 193, 2017/08

AA2017-0230.pdf:8.02MB

 Times Cited Count:3 Percentile:77.34(Chemistry, Physical)

Electric field of laser pulses which gives maximum selectivity in the isotope-selective rovibrational excitation of lithium chloride molecules is calculated. Applying the optimal control theory, we calculate optimal electric field to produce mixture of LiCl-35 ($$nu$$=0, $$J$$=0) and LiCl-37 ($$nu$$=1, $$J$$=1) from molecular ensemble of LiCl-35 ($$nu$$=0, $$J$$=0) and LiCl-37 ($$nu$$=0, $$J$$=0). As a result, it is found that electric field which permit rotational excitations only gives high yield in the selective excitation compared to the electric field which permit both rotational and vibrational excitations.

Journal Articles

Quantum control based on dynamic Stark effect

Kurosaki, Yuzuru

Shototsu, 12(4), p.114 - 125, 2015/07

no abstracts in English

Journal Articles

Quantum control of isotope-selective rovibrational excitation of diatomic molecules in the thermal distribution

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

Optical Review, 22(1), p.153 - 156, 2015/02

 Times Cited Count:6 Percentile:56.04(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.

Journal Articles

Dynamic discrimination of oriented molecules controlled with the nonresonant dynamic Stark effect induced by a single-cycle THz pulse

Kurosaki, Yuzuru; Akagi, Hiroshi; Yokoyama, Keiichi

Physical Review A, 90(4), p.043407_1 - 043407_9, 2014/10

 Times Cited Count:3 Percentile:83.18(Optics)

Journal Articles

Theoretical study on isotope-selective dissociation of the lithium chloride molecule using a designed terahertz-wave field

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. $$^7$$Li$$^{35}$$Cl 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 $$^7$$Li$$^{35}$$Cl. $$^7$$Li$$^{37}$$Cl 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 $$^7$$Li$$^{35}$$Cl was dissociated. The dissociation probability of $$^7$$Li$$^{37}$$Cl was less than 2%t.

Journal Articles

Quantum optimal control pathways of ozone isomerization dynamics subject to competing dissociation; A Two-state one-dimensional model

Kurosaki, Yuzuru; Ho, T.-S.*; Rabitz, H.*

Journal of Chemical Physics, 140(8), p.084305_1 - 084305_11, 2014/02

 Times Cited Count:6 Percentile:70.85(Chemistry, Physical)

Journal Articles

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

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.

Journal Articles

Theoretical study on isotope-selective excitation of diatomic molecules by a terahertz frequency comb

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 $$^7$$Li$$^{35}$$Cl molecule was excited selectively in gaseous mixture of $$^7$$Li$$^{35}$$Cl and $$^7$$Li$$^{37}$$Cl by adjusting pulse parameters. Moreover, the wave packet calculations were performed to investigate the dissociation process. More than half of $$^7$$Li$$^{35}$$Cl in the rovibrational state (v=0, J=150) were dissociated by the second pulse.

Journal Articles

Ab initio study on the low-lying potential energy curves of the diatomic cesium iodide cation (CsI$$^{+}$$)

Kurosaki, Yuzuru; Yokoyama, Keiichi

Computational and Theoretical Chemistry, 999, p.239 - 245, 2012/11

 Times Cited Count:4 Percentile:89.55(Chemistry, Physical)

Journal Articles

${it Ab inito}$ MRSDCI study on the low-lying electronic states of the lithium chloride molecule (LiCl)

Kurosaki, Yuzuru; Yokoyama, Keiichi

Journal of Chemical Physics, 137(6), p.064305_1 - 064305_9, 2012/08

 Times Cited Count:11 Percentile:55.34(Chemistry, Physical)

Journal Articles

Quantum optimal control for the full ensemble of randomly oriented molecules having different field-free Hamiltonians

Kurosaki, Yuzuru; Ichihara, Akira; Yokoyama, Keiichi

Journal of Chemical Physics, 135(5), p.054103_1 - 054103_6, 2011/08

 Times Cited Count:5 Percentile:80.62(Chemistry, Physical)

Journal Articles

Quantum control study of ultrafast isotope-selective vibrational excitations of the cesium iodide (CsI) molecule

Kurosaki, Yuzuru; Yokoyama, Keiichi; Yokoyama, Atsushi

Computational and Theoretical Chemistry, 963(2-3), p.245 - 255, 2011/02

 Times Cited Count:6 Percentile:83.34(Chemistry, Physical)

Journal Articles

Coherent correlation between nonadiabatic rotational excitation and angle-dependent ionization of NO in intense laser fields

Itakura, Ryuji; Hasegawa, Hirokazu*; Kurosaki, Yuzuru; Yokoyama, Atsushi; Oshima, Yasuhiro*

Journal of Physical Chemistry A, 114(42), p.11202 - 11209, 2010/07

 Times Cited Count:10 Percentile:63.49(Chemistry, Physical)

When neutral NO molecules are partly ionized in intense laser fields ($$I$$$$_{0}$$ $$>$$ 35 TW/cm$$^{2}$$), a hole in the rotational wave packet of the remaining neutral NO is created by the ionization, whose rate depends on the alignment angle of the molecular axis with respect to the laser polarization direction. Rotational state distributions of NO are experimentally observed and then the characteristic feature that the population at higher $$J$$ levels is increased by the ionization can be identified. Numerical calculation for solving time-dependent rotational Schrodinger equations including the effect of the ionization is carried out. The numerical results suggest that NO molecules aligned perpendicular to the laser polarization direction are dominantly ionized at the peak intensity of $$I$$$$_{0}$$ = 42 TW/cm$$^{2}$$, where the multiphoton ionization is preferred rather than the tunneling ionization.

Journal Articles

Multilevel effect on ultrafast isotope-selective vibrational excitations; Quantum optimal control study

Kurosaki, Yuzuru; Yokoyama, Keiichi; Yokoyama, Atsushi

Journal of Molecular Structure; THEOCHEM, 913(1-3), p.38 - 42, 2009/11

Journal Articles

Quantum control study of multilevel effect on ultrafast isotope-selective vibrational excitations

Kurosaki, Yuzuru; Yokoyama, Keiichi; Yokoyama, Atsushi

Journal of Chemical Physics, 131(14), p.144305_1 - 144305_9, 2009/10

 Times Cited Count:9 Percentile:67.16(Chemistry, Physical)

Journal Articles

Quantum optimal control of isomerization dynamics of a one-dimensional reaction-path model dominated by a competing dissociation channel

Kurosaki, Yuzuru; Artamonov, M.*; Ho, T.-S.*; Rabitz, H.*

Journal of Chemical Physics, 131(4), p.044306_1 - 044306_8, 2009/07

 Times Cited Count:25 Percentile:29.53(Chemistry, Physical)

Journal Articles

Isotope effects on the spin-density distribution in the H$$_6^{+}$$ clusters; Direct ${it ab initio}$ molecular dynamics study

Kurosaki, Yuzuru; Shimizu, Yuta*; Kumagai, Jun*

Chemical Physics Letters, 455(1-3), p.59 - 63, 2008/03

 Times Cited Count:2 Percentile:93.97(Chemistry, Physical)

Direct ab initio molecular dynamics calculations have been carried out for the H$$_6^{+}$$ cluster and its isotopic analogues: [H$$_{2}$$(H$$_{2}$$)H$$_{2}$$]$$^{+}$$, [H$$_{2}$$(H$$_{2}$$)D$$_{2}$$]$$^{+}$$, and [H$$_{2}$$(HD)H$$_{2}$$]$$^{+}$$. The calculations predict that the average geometry over the trajectories becomes asymmetric in both the deuterated clusters [H$$_{2}$$(H$$_{2}$$)D$$_{2}$$]$$^{+}$$ and [H$$_{2}$$(HD)H$$_{2}$$]$$^{+}$$, causing disproportion in the spin density that determines hyperfine coupling constants (HFCCs). This prediction agrees well with a recent ESR study that observed the isotope effects on the HFCCs for the central H$$_{2}$$ in these clusters generated in $$gamma$$-irradiated solid $$p$$-H$$_{2}$$. Thus the present result strongly supports the H$$_6^{+}$$ cluster formation in the solid $$p$$-H$$_{2}$$.

Journal Articles

Hydrogen-atom production channels of acetaldehyde photodissociation; Direct DFT molecular dynamics study

Kurosaki, Yuzuru

Journal of Molecular Structure; THEOCHEM, 850(1-3), p.9 - 16, 2008/02

 Times Cited Count:11 Percentile:69.07(Chemistry, Physical)

Direct density-functional (DFT) molecular-dynamics (MD) calculations have been carried out for the following two hydrogen atom production channels in acetaldehyde photodissociation on the lowest triplet-state (T$$_{1}$$) potential energy surface (PES): CD$$_{3}$$CHO$$rightarrow$$CD$$_{2}$$CHO+D(1); CD$$_{3}$$CHO$$rightarrow$$CD$$_{3}$$CO+H(2). The employed DFT method was B3LYP with the cc-pVDZ basis set. The average product hydrogen kinetic energies estimated from the results of the direct DFT MD calculations were 18.3 and 16.6 kcal mol$$^{-1}$$ for reactions 1 and 2, respectively, and these were half - two thirds of the previously measured values [Kang et al. Chem. Phys. Lett. 434 (2007) 6]. This is because of the low reverse barrier heights predicted at the B3LYP/cc-pVDZ level. The present results for the product hydrogen kinetic energies, however, agree qualitatively with the experimental measurements and strongly supports the mechanisms taking place on the T$$_{1}$$ PES.

Journal Articles

${it Ab inito}$ study on the ground and low-lying excited states of cesium iodide (CsI)

Kurosaki, Yuzuru; Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi

Journal of Chemical Physics, 128(2), p.024301_1 - 024301_7, 2008/01

 Times Cited Count:17 Percentile:43.56(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 $$Lambda$$-S states were first calculated and then those for 13 $$Omega$$ states including spin-orbit coupling were obtained. Spectroscopic constants for the calculated ground $$X$$ 0$$^{+}$$-state PEC were found to agree well with experiment. Transition dipole moments (TDMs) between $$X$$ 0$$^{+}$$ and the other $$Omega$$ states were also obtained and TDM between $$X$$ 0$$^{+}$$ and $$A$$ 0$$^{+}$$ was predicted to be the largest and that between $$X$$ 0$$^{+}$$ and $$B$$ 0$$^{+}$$ was the second largest around the equilibrium internuclear distance. Finally, vibrational levels of the $$X$$ 0$$^{+}$$ PEC for the two isotopic analogs, $$^{133}$$CsI and $$^{135}$$CsI, were numerically obtained and it was found that the $$v$$ = 136 state of $$^{133}$$CsI or $$^{135}$$CsI is most isolated from any adjacent vibrational level.

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