Mechano-ions produced by mechanical fracture of solid polymers

It is said that the free radical caused by C-C-bond scission, homogeneous scission, is produced by mechanical degradation. In addition to free radicals, ionic species are produced due to the mechanical destruction of the polymers. Studies in our group concerning this problem are summarized. When the polymers were ground with tetracyanoethylene (TCNE) powder in a vibration glass ball mill in vacuum in the dark at 77 K, the TCNE anion radical (TCNE$ \bar . $) was detected by electron spin resonance (ESR) method. The TCNE$ \bar . $ is formed by the abstraction of electrons by TCNE from the anion produced by a heterogeneous bond scission of carboncarbon bonds in the polymer main chain. The identification of TCNE$ \bar . $ was carried out by the spectral simulation on the basis of an anisotropic hyperfine tensor including a forbidden transition term. Several polymers were examined; polyethylene, polypropylene, poly(tetrafluoroethylene) and poly(vinylidene fluoride). The ratio of ionic species and free radicals is discussed.     

Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method

Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the (n,L)=(37,35) state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of nu(+)(HF)=12.895 96+/-0.000 34 GHz and nu(-)(HF)=12.924 67+/-0.000 29 GHz agree with recent theoretical calculations on a level of 6x10(-5).     

Primary populations of metastable antiprotonic (4)He and (3)He atoms

Initial distributions of metastable antiprotonic (4)He and (3)He atoms over principal (n) and angular momentum (l) quantum numbers have been deduced using laser spectroscopy experiments. The regions n = 37-40 and n = 35-38 in the two atoms account for almost all of the observed fractions [(3.0 +/- 0.1)% and (2.4 +/- 0.1)%] of antiprotons captured into metastable states.     

Synthesis, complexation, and fluorescence behavior of armed crown ethers carrying naphthyl group

Armed crown ethers (1-4) bonding through an amine, amide, ether, or ester linkage to naphthyl group were found to display unique photophysical properties in the presence of guest salts. Complexation of PET fluoroionophores (1a and 1b) with Zn(2+) increased the fluorescence intensities of the host by a factor of 2.4 and 2.7, respectively. (1)H and (13)C NMR analyses of this complexation behavior of 1a revealed that Zn(2+) strongly coordinates with the armed crown nitrogen to cause a dramatic decrease in an intramolecular charge-transfer character. The armed crowns (2 and 3), bonding through an ether or ester linkage to a naphthalene, gave fluorescence quenching with guest thiocyanates. While the amide derivative (4) exhibited high Ba(2+) fluorescence selectivity and in the presence of this cation the host fluorescence intensity was by a factor of 3.69.     

Cousinkomplex und Nennersysteme

Mathematische Zeitschrift -     

Wave nature of moving striations in a longitudinal magnetic field

Wave nature of stationary moving striations in helium and neon discharges in a uniform longitudinal magnetic field is studied. With the increase of the magnetic field, the frequency of natural striations decreases, while the wave length increases, and they damp out at high field region. Artificial excitations in these gases show that the wave length is proportional to the excitation frequency for given magnetic field and the slope of linear lines increases with the field. These wave nature of striations is explained following the dispersion relation derived from the consideration of waves of ionization and including effects of the magnetic field on the ionization.