It is proposed that a resonant mechanism should cause significant absorption of energy from intense laser pulses in plasma targets, and that the energy should be deposited in such a way as to form a very non-Maxwellian high temperature tail on the electron velocity distribution.Current interest in the controlled release of nuclear energy from laser-heated pellets of thermonuclear fuel has drawn interest to mechanioms by which laser light might be absorbed in the surface n i c-c'u yeixets. The large pulsed light intensities which are required for this heating and are beginning to be available in absorption experiments put the interaction of the laser radiation with the initially solid target in the approximately collisionless regime. Binary collisions between electrons driven by the wave fields and ions (sometimes called inverse bremstrahlung) can cause some absorption and may be quite important in allowing a weak precursor of a pulae to ionize the target and give the surface some thickness as assumed below, but as the intensity increases the fraction of the light energy absorbed by collisions becomes smaller.In thin letter we propose a resonant, collisionless absorption mechanism by which an inhomogeneous target plasma can absorb a significant fraction of obliquely incident laser light. He then show from numerical simulations that the energy is deposited in a very non-Maxwellian tail of the electron velocity distribution. Preliminary work on a relativistic absorption mechanism is also mentioned. If the electron density of the plasma, n, , and therefore the dielectric constant, «, are function* only of x, the light is Incident with the wave vector k iu the x,y plane at an angle 9 to the x axis, and the E field is polarized in this plane, then the c. (Fig. 2c) where ReB r (Fig. 2a) la ordes to roach this understanding of the colllslonless r&sonant absorption, which ia quite nonlinear, It was neceesary to treat the problem fey particle-ln-cell nunerlcal simulation. ' Since the probles la basically two-dimensional (except for a version of the problem which its infinite but not periodic io y), a celf-consiefrtnt treatment required fully •toctreaagiMtlc ewcdiiwiislottal (In x and y) afaulatlona which war* duna using ths ssthod of AppanAis. B in Sat. 3 with periodicity in y. The results of these two-dlaenslcnal sinulatlonc, which will be published In a more complete article, show that the following one-dimensional simulation method gives a qualitatively correct picture of the collisionless resonant electron heating in addition to affording higher spatial resolution. An oscillating E. (x,t) field is arbitrarily imposed, ar in Eq. (3) above, with a smooth bell-shaped profile in x centered at x = I, and broad enough to extend well on either side

The distribution ratios for 20°C of four n-alkanols between water and each of three n-alkanes have been determined. Combination of the results with calorimetrically-determined heats of solution of the alkanols in water and in alkanes at high dilution have yielded standard free energies, heats and entropies of transfer of the alkanols from water to the alkanes. The standard free energies and entropies of solution of alkanols in the alkanes have also been derived. In addition, integral heats of solution of I-octanol in n-decane at 20, 25 and 3 0 T have been determined in a concentration region where association of the alcohol is occurring. These heats can be adequately explained using an association model proposed by Heller and Fletcher, based on infra-red measurements.

The protonation of rhodium(l1) acetate by non-complexing non-oxidising acids such as fluoroboric acid gives the green rhodium(l1) cation Rh24+. The interaction with triphenylphosphine and carbon monoxide lead to the complexes R h (P Ph,) 3B F, and R h (CO) (P Ph,) 3B F, .The new ruthenium(l1) acetate Ru,(OCOMe), and its adducts with triphenylphosphine and pyridine have been characterised.The methanolic fluoroboric acid solutions of Rhrl and RuIr acetates and of Ru,(OAc),CI, in the presence of triphenylphosphine, are active catalysts for the homogeneous hydrogenation of alkenes, alkynes, and other unsaturated substances.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.

No abstract