Minimum volume stability limits for axisymmetric liquid bridges subject to steady axial acceleration

In this paper the influence of an axial microgravity on the minimum volume stability limit of axisymmetric liquid bridges between unequal disks is analyzed both theoretically and experimentally. The results here presented extend the knowledge of the static behaviour of liquid bridges to fluid configurations different from those studied up to now (almost equal disks). Experimental results, obtained by simulating microgravity conditions by the neutral buoyancy technique, are also presented and are shown to be in complete agreement with theoretical ones.     

The stereochemistry of asteriscunolides: An x-ray based correction

The application of X-ray diffraction methods has shown that the configurations of Asteriscunolides A and B at the Δ⁹ double bond are Z, rather than those previously proposed E, while the stereochemistries of Asteriscunolides C and D were correctly established. Some unexpected NMR data and the new assignment of the spectral signals, based on 2D-NMR $\text{C}\text{H}$ correlations and NOE-difference experiments are reported.     

Differential measurements on Ne*(2p3sP0.2)-Ne collisions in the hyperthermal energy range

Differential cross sections for collisions of metastable neon atoms with ground state neon atoms have been measured in the energy range 0.247–0.551 eV in a crossed nozzle beam experiment using heating and seeding techniques. At large angle, the cross sections exhibit a rainbow feature due to a hump in the 0_u⁻ and 1_u potentials. The present data are in good agreement with calculations based on potential energy curves deduced from previous experiments at thermal energy.     

Metastable rare gas atoms scattered by nano- and micro-slit transmission gratings

The transmission of metastable argon atoms through nano-slit or micro-slit gratings is studied by use of time of flight and angular analysis. This transmission departs from the simple geometric one essentially by two ways: (i) the elastic or diagonal part of the van der Waals (vW) interaction with the solid causes an angular narrowing of the emerging beam; (ii) the off-diagonal vW interaction induces the exothermal fine structure transition ³ P ₀↦³ P ₂ (ΔE = 175 meV) leading to large scattering angles; the resulting angular distribution is very sensitive to the roughness of the surface in the direction of the depth. An extension of these experiments to transversally coherent beams is proposed. It should be considered as a first step towards a new type of interferometer in which the inelastic diffraction makes the gratings work as beam splitters or mirrors. Received 6 July 2001 and Received in final form 17 September 2001