Decay Analysis of 197Tl* Compound Nucleus Formed in 16O + 181Ta Reaction at above Barrier Energy Ec.m.~100 MeV

The decay dynamics of 197Tl* compound nucleus has been studied within the framework of the dynamical cluster-decay model (DCM) at above barrier energy Ec.m. ≈ 100 MeV using quadrupole deformed configuration of decay fragments. The influence of various nuclear radius parameters on the decay path and mass distributions has been investigated by analysing the fragmentation potential and preformation probability. It is observed that 197Tl* nucleus exhibits the triple-humped mass distribution, independent of nuclear radius choice. The most preferred fission fragments of both fission modes (symmetric and asymmetric) are identified, which lie in the neighborhood of spherical and deformed magic shell closures. Moreover, the modification in the barrier characteristics, such as interaction barrier and interaction radius, is observed with the variation in the radius parameter of decaying fragments and influences the penetrability and fission cross-sections. Finally, the fission cross-sections are calculated for considered choices of nuclear radii, and the results are compared with the available experimental data.

Flash photolysis of phenylacetatopentaminecobalt(III) in aqueous solution. Generation of benzyl radicals and their reversible trapping by cupric ions in homogeneous and micellar solutions

The photodecomposition of [Co(NH3)5OC(O)CH2C6H5](ClO4)2 is a convenient source of benzyl radicals in aqueous systems. The radicals react with cupric ions with a rate constant of (2.1 ± 0.2) × 107 M−1 s−1 to yield a complex that is formed reversibly. This complex can decay to Cu(I), but at high radical concentrations the recombination of benzyl radicals in equilibrium with it can become the predominant decay path. The reaction of benzyl radicals (from 1,3-diphenylacetone) in anionic micelles in the presence of Cu2+ leads to strong signals from the same intermediate, CuCH2C6H52+.

Solvent and temperature dependence of absorption and phosphorescence of trans-diisothiocyanate (bis)ethylenediaminechromium(III) ion

An unusual case of absorption and fluorescence bands shifting in the same direction as solvent varies is reported. Solvent shifts in the quartet absorption maximum and doublet or phosphorescence emission maximum of trans-Cren2(NCS)2+ ion are related to the Gutmann solvent donor number. The correlation is discussed in terms of solvent effects on the vibrations identified as responsible for the vibronic transitions and are in agreement with Hollebone's notion of "vibronic" intersystem crossing. The activation parameters for decay of phosphorescence in eight solvents correlate by a Barclay–Butler plot and are consistent with the possibility of a single common dominant mechanism for the T-dependent decay path. They do not, however, depend on solvent donor numbers as quantum yields for substitution do. Therefore, they offered no new support for the notion that the pathway is by chemical reaction. The activation parameters also fail to correlate with solvent fluidity.