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Based on the Relativistic continuum Hartree-Bogoliubov (RCHB) theory, the pseudo-spin approximation in exotic nuclei is investigated in Zr and Sn isotopes from the proton drip line to the neutron drip line. The quality of the pseudo-spin approximation is shown to be connected with the competition between the centrifugal barrier (CB) and the pseudo-spin orbital potential ( PSOP ). The PSOP depends on the derivative of the difference between the scalar and vector potentials dV /dr. If dV /dr = 0, the pseudo-spin symmetry is exact. The pseudo-spin symmetry is found to be a good approximation for normal nuclei and to become much better for exotic nuclei with highly diffuse potential, which have dV /dr ∼ 0. The energy splitting of the pseudo-spin partners is smaller for orbitals near the Fermi surface ( even in the continuum ) than the deeply bound orbitals. The lower components of the Dirac wave functions for the pseudo-spin partners are very similar and almost equal in 1 magnitude.

Semianalytical expressions are suggested for the temperature dependence of those combinations of transport coefficients that govern the fission process. This is based on experience with numerical calculations within the linear response approach and the locally harmonic approximation. A reduced version of the latter is seen to comply with Kramers's simplified picture of fission. It is argued that for variable inertia his formula has to be generalized, as already required by the need that for overdamped motion the inertia must not appear at all. This situation may already occur above TϷ2 MeV, where the rate is determined by the Smoluchowski equation. Consequently, comparison with experimental results does not give information on the effective damping rate, as often claimed, but on a special combination of local stiffnesses and the friction coefficient calculated at the barrier.

The photochemical formation rates of hydroxyl radicals (OH radicals) in river water and seawater were determined by a simple, rapid and sensitive benzene probe method, in which phenol formed by the reaction between benzene and photochemically-generated OH radicals was analyzed by on-line preconcentration HPLC. The OH radical formation rates from well-known OH radical sources, such as nitrate, nitrite and hydrogen peroxide, were in good agreement with those reported previously. River water samples containing high concentrations of nitrate and nitrite were found to show high OH radical formation rates. Ten to 80% of the OH radical formation in river water and seawater was due to the photolysis of nitrate and nitrite, but OH radical formation from hydrogen peroxide was negligible. The OH radical formation from unknown sources other than nitrate, nitrite and hydrogen peroxide was strongly correlated to the amount of fluorescent matter.

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The interaction cross sections for A Na + 12 C reaction are calculated using Glauber model. The continuum Hartree-Bogoliubov theory has been generalized to treat the odd particle system and take the continuum into account. The theory reproduces the experimental result quite well. The matter distributions from the proton drip line to the neutron drip line in Na isotopes have been systematically studied and presented. The relation between the shell effects and the halos has been examined. The tail of the matter distribution shows a strong dependence on the shell structure. The neutron N = 28 closure shell fails to appear due to the coming down of the 2p 3/2 and 2p 1/2 . The development of the halo was understood as changes in the occupation in the next shell or the sub-shell close to the continuum limit.The central proton density is found to be decreasing near the neutron drip line, which is due to the proton-neutron interaction. However the diffuseness of the proton density does not change for the whole Na isotopes.

Previous computations of the potential landscape with the shapes parameterized in terms of Cassini ovaloids are extended to collective dynamics at finite excitations. Taking fission as the most demanding example of large scale collective motion, transport coefficients are evaluated along a fission path. We concentrate on those for average motion, namely stiffness C, friction \gamma and inertia M. Their expressions are formulated within a locally harmonic approximation and the help of linear response theory. Different approximations are examined and comparisons are made both with previous studies, which involved different descriptions of single particle dynamics, as well as with macroscopic models. Special attention is paid to an appropriate definition of the deformation of the nuclear density and its relation to that of the single particle potential. For temperatures above 3 MeV the inertia agrees with that of irrotational flow to less than a factor of two, but shows larger deviations below, in particular in its dependence on the shape. Also friction exhibits large fluctuations along the fission path for small excitations. They get smoothed out above 3 - 4 MeV where \gamma attains values in the range of the wall formula. For T > (or=) 2 MeV the inverse relaxation time \beta = \gamma /M turns out to be rather insensitive to the shape and increases with T.Comment: 30 pages, Latex, 15 Postscript figures; to appear in PRC; e-mail: hhofmann@physik.tu-muenchen.de www home page: http://www.physik.tu-muenchen.de/tumphy/e/T36/hofmann.htm

We present a realistic calculation of the frictional coefficients for 2SSi+2~ system using the two-center shell model on the basis of the linear response theory. Adopting the center separation R and the deformation 6 as collective variables we study the dependence of frictional coefficients 7RR, )'R6 and y66 on those variables, for various values of the neck parameter e, the temperature T and the smearing width F. The direct application of the linear response theory to the two-center potential gives non-vanishing friction for the simple translational motion of the two fragments even when they are far apart. A method to avoid this energy dissipation is proposed and is used in the calculation. Results show that the form factor of the frictional force is surface-peaked and the peak becomes lower as the prolate deformation or neck formation increases. Temperature dependence is mild, but is not negligible. We compare our 7RR and ~',~ with other models.