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

https://doi.org/10.3390/universe5050109

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.

The Role of dissociation channels of excited electronic states in quantum optimal control of ozone isomerization; A Three-state dynamical model

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

Chemical Physics, 469-470, p.115 - 122, 2016/05

https://doi.org/10.1016/j.chemphys.2016.02.015

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

https://doi.org/10.1007/s10043-015-0025-5

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.

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

https://doi.org/10.7566/JPSCP.1.013093

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.

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.

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

https://doi.org/10.1016/j.comptc.2012.09.007

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

https://doi.org/10.1063/1.3618719

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

https://doi.org/10.1021/jp102840t

When neutral NO molecules are partly ionized in intense laser fields ( 35 TW/cm), 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 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 = 42 TW/cm, where the multiphoton ionization is preferred rather than the tunneling ionization.

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

https://doi.org/10.1063/1.3245401

Isotope effects on the spin-density distribution in the H clusters; Direct molecular dynamics study

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

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

https://doi.org/10.1016/j.cplett.2008.02.072

Direct ab initio molecular dynamics calculations have been carried out for the H cluster and its isotopic analogues: [H(H)H], [H(H)D], and [H(HD)H]. The calculations predict that the average geometry over the trajectories becomes asymmetric in both the deuterated clusters [H(H)D] and [H(HD)H], 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 in these clusters generated in -irradiated solid -H. Thus the present result strongly supports the H cluster formation in the solid -H.