Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T _1/2 > 1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic ⁶⁸Ni and its neighbor ^69,71Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed. Received: 1 May 2001 / Accepted: 4 December 2001     

Comments on the bremsstrahlung cross section formula using exact electron-distorted wave functions

Rozics and Johnson's formula is examined and its inconsistency is pointed out.     

Heavy element nuclear chemistry at JAERI

The present status of heavy element nuclear chemistry research at JAERI (Japan Atomic Energy Research Institute) is reviewed. Production of the transactinide nuclei ²⁶¹Rf and ²⁶²Db via the reactions of ²⁴⁸Cm(¹⁸O,5n) and ²⁴⁸Cm(¹⁹F, 5n), respectively, at the JAERI tandem accelerator is reported. Study of the aqueous chemistry of Rf is being carried out with a newly developed rapid ion-exchange separation apparatus. Anion-exchange behavior of Rf in acidic solution is briefly discussed. Recent experimental results on decay studies of neutron-deficient actinide nuclei using the gas-jet coupled JAERI-ISOL are given. We also discuss characteristics of nuclear deformation properties at scission in symmetric and asymmetric fission of actinides. Prospects for studies in the near future are briefly considered.     

Fluorescence spectra,fluorescence quantum yields and fluorescence lifetimes of polymers having trans-1,2-dicarbazolylyclobutane or carbazolyl group

Quantum yields, lifetimes and shapes of fluorescence from polymers containing the trans-1,2-dicarbazolylcyclobutane (DCZB) or carbazolyl structures were studied in N,N-dimethylformamide. No sandwich-type excimer formation was observed for DCZB polymers. The so-called second excimer observed in poly(9-vinylcarbazole) might also be produced in poly(9-ethyl-3-vinylcarbazole).     

The roles of hetero atoms in solvolytic reactions—II: Transannular participation by neighbouring sulphur atom

Esters of sulphur-containing 5- and 6-membered heterocycles, tetrahydro-3- and 4-thiopyranol and their 3- and 4-methyl, phenyl derivatives, and tetrahydro-2-thiophenemethanol, were synthesized. The solvolysis of β-thioesters in 80% aqueous acetone resulted in strong transannular S-participation and the products of solvolysis substantiated formation of bicyclic episulphonium ion intermediates. Such participation is considered to be present even in a tertiary system. On the other hand, γ-thioesters were solvolysed without any transannular S-participation,     

Isomorphic electron orbitals for vibronic flexibility in a cyclopropenyl radical molecular device

Summary The vibronic character of this molecular device has been studied using isomorphic electron orbitals. The leading role of the softest vibrational mode for the electron transport process is stressed by the quantum mechanical treatment of the rearrangement operator. The theory was used to investigate the possible function of the soliton valve, which has been suggested as a switching tip. The electronic flexibility of the cyclopropenyl radical with respect to molecular vibrations, which is important for the function of the molecular device, is well characterized by the hardness and softness of the electron structure in terms of the orbital energy-occupation number correlation diagram.     

A quantum chemical study of interchain hopping model of negatively charged solitons in polyacetylene

Phonon-assisted interchain hopping of negatively charged solitons in polyacetylene has been studied using a local chemical reaction model CH + CH₄ → CH₄ + CH. Quantum chemical characteristics of the electron transfer process have been analyzed in terms of the dynamic electron density and the mutual polarization moment. The CH stretching vibrational motion of CH₄, which is a local model of the sp³ defect, has been found to play a significant role for the electron transfer. The excitation of the corresponding vibrational mode of the sp³ defect would promote the interchain hopping of the charged soliton. The electron transfer process has also been studied in terms of the “regional” density functional theory. It has been shown that the driving force of the electron transfer is represented by the regional chemical potentials.     

Microdetermination of fluorine in organic compounds by oxygen flask combustion and conductometric titration

For the conductometric titration of fluoride with calcium acetate, solvent system in sample solution and titrant, concentration, and acidity of sample solution were examined to establish the titration conditions. Results of these examinations were transferred to the microdetermination of fluorine in organic compounds using oxygen flask combustion method.Comparative examination between quartz and Pyrex flasks for the combustion of fluorine samples indicated that good results were obtained by the use of the former flask, whereas the use of the latter one gave negative values of 1.0–1.6% due to the formation of boron fluoride during the combustion.