Nonempirical statistical theory for molecular evaporation from nonrigid clusters

We propose a nonempirical statistical theory to give the reaction rate and the kinetic energy distribution of fragments for molecular evaporation from highly nonrigid atomic and van der Waals clusters. To quantify the theory, an efficient and accurate method to evaluate the absolute value of classical density of states (the Thomas-Fermi density in phase space) and the flux at the so-called dividing surface is critically important, and we have devised such an efficient method. The theory and associated methods are verified by numerical comparison with the corresponding molecular dynamics simulation through the study of Ar(2) evaporation from Ar(8) cluster, in which evaporation is strongly coupled with structural isomerization dynamics. It turns out that the nonempirical statistical theory gives quite an accurate reaction rate. We also study the kinetic energy release (KER) arising from these evaporations and its Boltzmann-like distribution both for atomic and diatomic evaporations. This provides a general relation between the KER and temperature of the fragments.     

Minimax approximation for the decomposition of energy denominators in Laplace-transformed Møller-Plesset perturbation theories

We implement the minimax approximation for the decomposition of energy denominators in Laplace-transformed Moller-Plesset perturbation theories. The best approximation is defined by minimizing the Chebyshev norm of the quadrature error. The application to the Laplace-transformed second order perturbation theory clearly shows that the present method is much more accurate than other numerical quadratures. It is also shown that the error in the energy decays almost exponentially with respect to the number of quadrature points.     

Characteristics of VHF H2 Plasma Produced at High Pressure

A VHF H₂ plasma was produced with the multi rod electrode at high pressure and the plasma parameters were measured as a function of pressure for different VHF powers at 60 MHz. It was found that when the pressure is increased, the ion saturation current peaks at certain pressure and finally decreases at high pressures, while the electron temperature is around 10 eV. The wall potential at high pressure was lower than the values estimated from the electron temperature using the probe theory. Furthermore, the anomalous reduction of the electron saturation current was observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and photo-crosslinking of oriented side-chain liquid crystalline polymers

New photo-crosslinkable side-chain liquid-crystalline methacrylate polymers comprising m-[4′-(n-cinnamoyloxyalkoxy)biphenyl-4-yloxy]alkyl groups (m, n = 2, 6) were synthesized. All polymers exhibit a nematic liquid-crystalline phase depending on the spacer length (5a–5d) . Aligned thin films could be obtained using a rubbed polyimide-coated substrate, and they could be photo-crosslinked without change in the aligned structure. The photo-crosslinked film of 5d (m = n = 6) showed a stable alignment up to 300°C.     

Electronic and nuclear flux analysis on nonadiabatic electron transfer reaction: A view from single-configuration adiabatic born–huang representation

A detailed flux analysis on nonadiabatically coupled electronic and nuclear dynamics in the intramolecular electron transfer of LiF is presented. Full quantum dynamics both of electrons and nuclei within two-state model has uncovered interesting features of the individual fluxes (current of probability density) and correlation between them. In particular, a spatiotemporal oscillatory pattern of electronic flux has been revealed, which reflects the coherence coming from spatiotemporal differential overlap between nuclear wavepackets running on covalent and ionic potential curves. In this regard, a theoretical analogy between the nonadiabatic transitions and the Rabi oscillation is surveyed. We also present a flux–flux correlation between the nuclear and electronic motions, which quantifies the extent of deviation of the actual electronic and nuclear coupled dynamics from the Born–Oppenheimer adiabatic limit, which is composed only of a single product of the adiabatic electronic and nuclear wavefunctions. © 2018 Wiley Periodicals, Inc.     

Optical anisotropy of a photoreacted side-chain liquid-crystalline polymer induced by linearly polarized UV light

Linearly polarized (LP) UV photoreaction of a photo-crosslinkable side-chain liquid-crystalline polymer (SLCP) containing photoreactive cinnamoyl and biphenyl mesogenic groups ( 1 ) was studied. The optical anisotropy of the polymer film was induced by the LP-UV photoreaction and was investigated by the temperature-controlled polarized UV absorption spectroscopy and polarized FT-IR measurements. The reorientation of the nonreacted mesogenic groups along to the Ê direction of the incident LP-UV light during the photoreaction occurred at the LC temperature range of the polymer, and the induced birefringence Δn was about 0.02. Because of the high-density photo-crosslinking, the LP-UV photoreacted film showed orientational stability up to 160°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1521–1526, 1998     

Chemiexcitation efficiency for the charge-transfer-induced chemiluminescent decomposition of 3-hydroxyphenyl-substituted dioxetanes in an aqueous system

The decomposition of 3-oxyphenyl-3-methoxy-4-(2′-spiroadamantane)-1,2-dioxetane (A) and 5-tert-butyl-4,4-dimethyl-1-(3-oxyphenyl)bicyclo[3.2.0]heptane (B) in NaOH/H₂O gives light in poor yield, which is several orders of magnitude lower than that in aprotic solvents. To understand the poor chemiluminescence efficiency in NaOH/H₂O, we investigated the behaviors of the authentic emitters, methyl 3-oxidobenzoate (C) and 2,2,4,4-tetramethyl-3-oxopentyl 3-oxidobenzoate (D). We found that D was weakly fluorescent though hydrolyzed in NaOH/H₂O, and estimated that the singlet-chemiexcitation efficiency Φ_S was 6.1 × 10⁻³ for the decomposition of B in NaOH/H₂O. On the other hand, Φ_S for A could not be estimated, since C was hydrolyzed too rapidly to observe its fluorescence.     

Development of a gas cell-based laser ion source for RIKEN PALIS

We developed a prototype laser ionization gas cell with a beam extraction system. This device is for use of PArasitic Laser Ion-Source (PALIS), which will be implemented into RIKEN’s fragment separator, BigRIPS as a part of SLOWRI. Off-line resonant laser ionization for stable Co, Cu, Fe, Ni, Ti, Nb, Sn, In and Pd inside the gas cell, ion extraction and transport to the high-vacuum region via SPIG and QMS have been confirmed (Sonoda et al, Nucl Instrum Meth B 295:1, 2013).     

Very fast tunneling in the early stage of reaction dynamics

The difference between quantum and classical survival probabilities for molecular dissociation dynamics in the time domain, which arises mainly from quantum mechanical tunneling, has interesting characteristics that are not noticed through the counterpart in energy domain. It is shown that the early stage undergoes a fast tunneling, while the later stage is characterized with a long-lasting slow tunneling. The mechanism of this behavior is analyzed in terms of a quasi-semiclassical theory featuring the geometrical distribution of the so-called tunneling points. In particular, the role of dynamical tunneling is discussed as a phenomenon that typifies the time dependence of tunneling dynamics. It is predicted that these tunneling characteristics will be reflected in the isotope effect and should be experimentally observable.