Limits on the localized interpretation of molecular orbital wavefunctions

A new measure of orbital localizability is proposed. The actual improvement in classical electrostatic interpretations of electronic energy contributions on localization of CH₄, NH₃, H₂O, HF and Ne LCAO wavefunctions is computed to be small. Substantial valence LMO spatial overlapping remains.     

Whitworth runs on a circle

Summary Suppose different classes of items, for example, beads of different colours, are placed in a circle. Two probability models have been proposed, which lead to different distributions of runs, i.e. sequences of one colour. Barton and David [3] have called these Whitworth runs and Jablonski runs, and have tabulated the distributions for small samples. Asano [1] has extended the tabulations for Jablonski runs. In this paper, Whitworth runs are examined, particularly some approximations to the distributions which avoid extensive tabulations. Some potential uses of Whitworth runs are also pointed out.     

Electroproduction of π0 mesons in the resonance region at q2=1.0 (GeV/c)2

Data are presented for the reaction ep → epπ⁰ at a nominal momentum transfer squared of 1.0 (GeV/c)². The data were obtained using an extracted electron beam from NINA and two magnetic spectrometers for coincidence detection of the electron and proton. Differential cross sections have been measured for isobar masses in the range 1.19–1.73 GeV/c².     

Fission of 232Th, 238U, 244Pu, 248Cm induced by Xe and Kr ions at coulomb barrier energies

Excitation functions and angular distributions have been measured for the fission of ²³²Th, ²³⁸U, ²⁴⁴Pu and ²⁴⁸Cm induced by ⁸⁶Kr and ¹³⁶Xe ions at energies in the vicinity of the Coulomb barrier. No large differences as a function of either target or projectile were found. These results suggest that the main process occuring is not Coulomb fission.     

Sensitivity of magneto-optic rotation to variations in isotopic composition

The technique has the advantage of allowing isotopic differences to be detected using a standard atmospheric atomiser and a conventional hollow cathode source. The measurements are sufficiently robust to tolerate a limited variability of sample composition, background absorption from matrix species, and some instrumental parameters such as source intensity. Different isotopes show different responses with varying magnetic field strength across the atomiser. This allows a distinction to be made between the isotopes even though only a single source of natural isotopic composition is used. Results illustrating this behaviour are given for Pb²⁰⁶, Pb²⁰⁷, Pb²⁰⁸.     

Effect of laser intensity on fast-electron-beam divergence in solid-density plasmas

Metal foil targets were irradiated with 1 mum wavelength (lambda) laser pulses of 5 ps duration and focused intensities (I) of up to 4x10;{19} W cm;{-2}, giving values of both Ilambda;{2} and pulse duration comparable to those required for fast ignition inertial fusion. The divergence of the electrons accelerated into the target was determined from spatially resolved measurements of x-ray K_{alpha} emission and from transverse probing of the plasma formed on the back of the foils. Comparison of the divergence with other published data shows that it increases with Ilambda;{2} and is independent of pulse duration. Two-dimensional particle-in-cell simulations reproduce these results, indicating that it is a fundamental property of the laser-plasma interaction.