Abstract. X-rays are emitted with the radiative recombination of free electrons in an electron cooler of a heavyion storage ring. Due to a small width of the X-ray lines, an observation angle close to 0 ° and an accurate determination of the ion velocity, the ground-state Lambshift of hydrogenlike uranium (470 _+ 16) eV could be measured to an accuracy of 3.4%. A re-evaluation of a measurement of the lsl/2 Lambshift in hydrogenlike gold gave a new value of (202.3 + 7.9) eV as compared to the former value of(212 + 15) eV. The results are in excellent agreement with QED calculations and are more precise than any other measurements previously reported for a high-Z, hydrogenlike ion.

In high-energy atomic collisions between bare high-Z projectiles and low-Z target atoms, an electron may be captured radiatively into an excited projectile state which subsequently decays by x-ray emission. This process is the inverse of two-photon-one-electron ionization, in which the first photon resonantly excites an electron from the hydrogenic 1s 1͞2 ground state and a second photon ionizes the excited electron. We present an experimental and theoretical study of the angular distribution of the Ly-a 1 (2p 3͞2 ! 1s 1͞2 ) x rays following radiative electron capture. From the observed anisotropic emission pattern a significant alignment of the intermediate 2p 3͞2 state is deduced. [S0031-9007(97)04327-5] PACS numbers: 34.70. + eRecent experimental studies of inner-shell photoionization have stressed the role of relativistic effects and higher transition multipoles beyond the electric-dipole approximation [1]. Sensitivity to such effects is enhanced by measurement of angular distributions rather than angle integrated cross sections [2]. Interestingly, information on these higher-order effects in the photoionization of inner shells of very heavy atoms can also be obtained through measurements of angular distributions of photons emitted following radiative electron capture (REC) into excited states of highly charged ions. For the case of the heaviest atoms, REC into bare ions provides the only experimental access for photoionization studies in the absence of electron screening corrections.With present-day accelerators, it is possible to produce relativistic beams of bare high-Z ions like U 921 and Pb 821 [3,4]. If a high-Z ion collides with a low-Z target atom, it may capture an electron radiatively, that is, with the simultaneous emission of a photon, which carries away the excess energy and momentum. Since the loosely bound target electrons can be considered as quasifree, REC is essentially the inverse of the photoelectric effect [5,6]. If REC occurs into an excited state, say the 2p 3͞2 level, this state decays into the 1s 1͞2 ground state by emitting a Lyman-a 1 photon. For high-Z projectiles and low-Z targets nonradiative capture plays no role [7]; hence the detection of a decay photon in coincidence with the down-charged projectile is a clear indication of a two (or more)-photon process. This reaction is the inverse of an otherwise unobservable high-energy two-photon-one-electron ionization: Initially, a photon resonantly excites the hydrogenic 2p 3͞2 state from the 1s 1͞2 ground state, and, subsequently, another photon ionizes the excited electron within the lifetime of the 2p 3͞2 state, i.e., a time of the order of 10 217 s. In this Letter, we are interested in the magnetic subshell population produced by REC into the 2p 3͞2 state. This provides us with detailed information on the dynamics of the photoionization process for a high-Z one-electron ion, in which the electron-photon interaction is governed by relativistic effects. Information on the population of magnetic substates is obtained either from the ...

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Three genes from Ralstonia eutropha necessary for poly(3-hydroxybutyrate) (PHB) synthesis were introduced into the hairy roots of sugar beet. Transformation of a vector construct harbouring the PHB genes, each fused to the coding region of the pea ribulose-bisphosphate carboxylase plastid targeting sequence, resulted in 20 transgenic hairy-root clones, producing up to 55 mg high molecular PHB/g dry weight, as identified by gas chromatography, gel permeation chromatography and HPLC. Accumulation of PHB polymer in sugar beet root leucoplasts was confirmed by transmission electron microscopy. Thus, for the first time, plastidic PHB production was demonstrated for roots of a carbohydrate-storing crop plant.