Transition metal complexes of γ-mercaptoalkylpiperidines

Summary Complexes with 1-methyl-3-(mercaptomethyl)piperidine (LH) and 1-methyl-2-(2-mercaptoethyl)piperidine (LH) Ligands in their thiolato (R), andN-protonated (HR) orN-methylated (MeR) zwitterionic form, of stoichiometry MR₂ (M=Ni, R=L or L; M=Cd, R=L), MR (M=Cu or Ag, R=L and L), [Ni(MeR)₂]I₂ · nH₂O (R=L, n=1; R=L, n=2), [Ni(HR)₂]X₂ (R=L or L, X=ClO₄; R=L, X=Br), and [Ag(HR)] ClO₄ (R=L) have been prepared and characterized. According to i.r. and electronic spectra, and magnetic measurements the nickel complexes exhibit polymeric frameworks built up from mercapto-bridged metal atoms in square-planar environments. Complexes with copper, silver, and cadmium exhibit similar polymeric arrangements through bridging sulphur atoms but with a different geometry at the metal centers, the first two being mainly linear, as anticipated, and the latter tetrahedral. In no case does coordinationvia nitrogen take place and therefore these ligands behave simply as mercaptides.     

The Ag(s)/AgI(s)/graphite solid cell as iodine sensor: speed of response and use of Cs-doped AgI as electrolyte

The time response of a Ag(s)/AgI(s)/graphite(s), I₂(g) galvanic cell as iodine sensor was studied using both pure AgI and CsI doped AgI as electrolyte. The use of doped silver iodide expanded considerably the working temperature. An analytical modeling of the sensor response is presented. Electronic Publication     

Vibrationally state-selective spin-orbit transfer with strong nonresonant pulses

By dynamic Stark shift using strong nonresonant pulses, we show that it is in principle possible to prepare arbitrary superposition states of mixed multiplicity. By a proper choice of parameters, the transfer of population is shown to follow the Rabi formula, where the initial and target states are now vibrational states of two light-induced molecular potentials of different multiplicity. Starting from nonstationary wave packets, the spin transfer can proceed via parallel transfer using a single pulse or by sequential transfer using a pulse sequence. A simple model is proposed to analyze the properties of both schemes and the feasibility of their experimental implementation for spin-orbit transitions in Rb2.     

The key role of off-axis singularities in free-space vortex transmutation

We experimentally demonstrate the generation of off-axis phase singularities in a vortex transmutation process induced by the breaking of rotational symmetry. The process takes place in free space by launching a highly charged vortex, owning full rotational symmetry, into a linear thin diffractive element presenting discrete rotational symmetry. It is shown that off-axis phase singularities follow straight dark rays bifurcating from the symmetry axis. This phenomenon may provide new routes toward the spatial control of multiple phase singularities for applications in atom trapping and particle manipulation.     

Rescaled Lévy-Loewner hulls and random growth

We consider radial Loewner evolution driven by unimodular Lévy processes. We rescale the hulls of the evolution by capacity, and prove that the weak limit of the rescaled hulls exists. We then study a random growth model obtained by driving the Loewner equation with a compound Poisson process. The process involves two real parameters: the intensity of the underlying Poisson process and a localization parameter of the Poisson kernel which determines the jumps. A particular choice of parameters yields a growth process similar to the Hastings-Levitov HL(0) model. We describe the asymptotic behavior of the hulls with respect to the parameters, showing that growth tends to become localized as the jump parameter increases. We obtain deterministic evolutions in one limiting case, and Loewner evolution driven by a unimodular Cauchy process in another. We show that the Hausdorff dimension of the limiting rescaled hulls is equal to 1. Using a different type of compound Poisson process, where the Poisson kernel is replaced by the heat kernel, as driving function, we recover one case of the aforementioned model and SLE(κ) as limits.