Two-body T-matrix continued off the energy shell

A generalized parametrization scheme, which treats both half-shell and off-shell scattering on equal footing, is derived for the two-particle transition operator. The appropriate theory in respect of this is developed by using a wave function approach to off-shell scattering and the computational procedure to be followed is demonstrated by means of a model calculation.     

On the nature of the phase transition in the KDP systems

Using the Landau theory of phase transitions it has been shown that for a second order phase transition Ω/k_BT_c ? 0.01. and its isomorphs 4Ω/J¹ ? 1 and for a first order transition Ω/k_BT_c ? 0.01.     

First excited 0+ states in the germanium isotopes via the Se(d, 6Li) reaction

A systematic study of the even-A germanium isotopes with mass 70 ≦ A ≦ 78 via the Se(d, ⁶Li) reaction has been performed at E_d = 45 MeV. The reaction products were momentum analysed and mass identified with a QMG/2 magnetic spectrograph and the accompanying focal-plane detector system. The main emphasis of this investigation was on the nature of the first excited 0⁺ states. The striking variation in strength from one isotope to the other already observed in the (p, t) reactions to the same final nuclei is also seen for the α-pickup reaction. Previously derived wave functions that assume the excited 0⁺₂ states to be pure proton configuration states can also account for the present results.     

Cuboctahedral symmetry in the aggregation of [60]fullerene in polar organic media

[60]fullerene is known to aggregate in water and all experimental and theoretical evidences support that the aggregates contain (C60)13 units. No chemical kinetic study of the effect of solvent polarity on the aggregation of C60 has so far been reported. Here we show by simple kinetic study of the aggregation process and by scanning electron microscopy (SEM) that when methanol is added to a solution of [60]fullerene in CCl4, spontaneous aggregation starts immediately and the aggregation numbers (n) found to be dependent on the CCl4:CH3OH ratio (v/v) of the medium. One particular ratio of the two liquids gives uniformly sized (C60)13 clusters for about 10 min. The values of n correspond to the minima of the previously reported energy calculations and in the present work, they have been shown to be a natural consequence of stacking of cuboctahedra made up of C60 molecules. A Young diagram-like method has been developed for counting the number of C60 molecules in these cuboctahedral stacks and the numbers obtained from this model and also from the present chemical kinetic and SEM studies agree very well with the "magic numbers" obtained by earlier mass spectrometric studies.     

Kinetics of self-decomposition and hydrogen atom transfer reactions of substituted phthalimide N-oxyl radicals in acetic acid

Kinetic data have been obtained for three distinct types of reactions of phthalimide N-oxyl radicals (PINO(.)) and N-hydroxyphthalimide (NHPI) derivatives. The first is the self-decomposition of PINO(.) which was found to follow second-order kinetics. In the self-decomposition of 4-methyl-N-hydroxyphthalimide (4-Me-NHPI), H-atom abstraction competes with self-decomposition in the presence of excess 4-Me-NHPI. The second set of reactions studied is hydrogen atom transfer from NHPI to PINO(.), e.g., PINO(.) + 4-Me-NHPI <=> NHPI + 4-Me-PINO(.). The substantial KIE, k(H)/k(D) = 11 for both forward and reverse reactions, supports the assignment of H-atom transfer rather than stepwise electron-proton transfer. These data were correlated with the Marcus cross relation for hydrogen-atom transfer, and good agreement between the experimental and the calculated rate constants was obtained. The third reaction studied is hydrogen abstraction by PINO(.) from p-xylene and toluene. The reaction becomes regularly slower as the ring substituent on PINO(.) is more electron donating. Analysis by the Hammett equation gave rho = 1.1 and 1.8 for the reactions of PINO(.) with p-xylene and toluene, respectively.     

Reductive nitrosylation of tetraoxometallates—XI. Molybdate hydroxylamine reaction in the presence of cyanide: Synthesis of mono- and dinitrosyl cyan

The new molybdenum cyanonitrosyl complexes, R₂[Mo(NO)(CN)₅]·2H₂O (R = Ph₄P and Bu₄N) and [Mo(NO)(CN)₃(L-L)]·H₂O [L-L =     

On circular designs

Summary A general method of analysis of circular designs (Das [3]) is suggested. Average efficiency factors of these designs have been tabulated.A-optimality of circular designs has been studied in comparison to group divisible incomplete block designs.