Ppn Reaction Research Articles

Organometallic gold derivatives with the [1-Si tBuMe 2-1,2-C 2B 1 0H 1 0]-carboranyl ligand. Crystal structure of [1-{Au (PPh 3)}-2-Si tBuMe 2-1,2-C 2B 10H 10

Reaction of 1-Li-2-Si t BuMe 2-1,2-C 2B 10H 10 with [AuCIL] (L=PPh 3, PPh 2Me, AsPh 3) in molar ratio 1:1 affords the organometallic gold complexes [1-AuL-2-Si t BuMe 2-1,2-C 2B 10H 10]. The complex PPN[Au{2-Si t BuMe 2-1,2-C 2B 10H 10} 2] (PPN=N(PPh 3) 2) has also been synthesised by reaction of PPN[AuCl 2] with 1-Li-2-Si t BuMe 2-1,2-C 2B 10H 10 in molar ratio 1:2. The crystal structure of [1-{Au (PPh 3)}-2-Si t BuMe 2-1,2-C 2B 10H 10] has been established by X-ray diffraction.

Reaction Mechanism in the N -> N Reactions

A model for two-pion photoproduction from nucleons proposed previously is modified to simultaneously explain the total cross sections in all isospin channels and the invariant mass spectra. Using this model, we discuss the reaction mechanism in the γN →ππN reaction.

π+ → π+π± on deuterium at Tπ+ = 283 MeV

New experimental results on the π + d → π + π − pp and π + d → π + π + nn reactions at T π 1 = 283 MeV are presented. In-plane coincidence data were taken with the CHAOS spectrometer using pions from the M11 channel at TRIUMF. Because of the quasi-free nature of the pion-production reaction, the present study is equivalent to studying the elementary π + N → π + π ± N reactions on protons and neutrons simultaneously. These exclusive measurements provide a set of many-fold differential cross sections which are an ideal testing ground for microscopic models describing the πN → ππN reaction. The interpretation of the data relies on a model which is based on effective chiral Lagrangians to describe the piece of the reaction that includes only π's and N's, and on effective Lagrangians to account for intermediate Δ's and N ∗' s . The measured many-fold differential cross sections are used to constrain some parameters of the model (ξ, f Δ , C, g N ∗ Δπ and g N ∗Nπ ). Finally, the π + π ± invariant mass distributions display no evidence of strongly interacting pion pairs in either the I = J = 0 or the I = 2 J = 0 channels.

The [formula omitted] amplitudes extracted from the γp → π+π−p reaction and comparison to quark models

The γp → π + π − p reaction, in combination with data from the πN → ππN reaction has been recently analyzed and allows one to obtain the s- and d-wave amplitudes for the N ∗ (1520) decay into Δπ with absolute sign with respect to the N ∗ (1520) → Nγ helicity amplitudes. In addition one obtains the novel information on the momentum dependence of the amplitudes. In the present paper we show how this new information poses new constraints to quark models of hadron structure. In particular we show that the signs and the momentum dependence of these amplitudes coincide with those given by non relativistic constituent quark models. The absolute values provided by these models agree only qualitatively, and a discussion is done on the reasons for it and possible ways to improve.

The deuteron D-state probability

A method of direct determination of the deuteron D-state probability from the experiment, based on the d ↑ p → ppn reaction analyzis is suggested. Using the known results on the vector analyzing power in elastic NN-scattering, the values of the overall nucleon polarization and the deuteron vector polarization have been obtained. The probability of the deuteron D-state is estimated to be w D = 0.078 ± 0.046.

Analysis of data on low energy πN → ππN reaction I. Total cross sections

This is the first of a series of papers on a consistent model independent analysis of the complete experimental information on the reaction $\pi N \rightarrow \pi \pi N$ at pion momenta up to 500 MeV/c. The paper summarizes the theoretical approach and details of the computational procedure. The complete database on total cross sections in 5 $\pi \pi N$ channels is given together with a critical discussion of their model independent analysis.

Structural characterization of two large bismuth–cobalt carbonyl clusters: (PPN)2[Bi4Co9(CO)8(µ-CO)8]·2THF and (PPN)2[Bi8Co14(CO)12(µ-CO)8]·1.08THF

The reaction of PPN[Bi2Co4(CO)10(µ-CO)] with Mo(CO)3(toluene) in THF yields, after slow oxidation, the large clusters, (PPN)2[Bi4Co9(CO)8(µ-CO)8] and (PPN)2[Bi8Co14(CO)12(µ-CO)8][PPN = bis(triphenylphosphine)iminium] which exhibit close-packed arrays of main group elements and transition metal atoms.

Experimental test of chiral symmetry with πp → ππN reactions

Experimental test of chiral symmetry with πp → ππN reactions

Chiral symmetry and the near-threshold pion-induced 2 π production on the nucleon : II. Relativistic corrections and ππ initial- and final-state interactions

Some extensions of a model for the πN → ππN reaction, presented in a preceding paper, are outlined: the leading relativistic corrections to the static treatment of the baryons are derived and the main features of the ππ interaction in the initial and final state are included via σ- and ϱ-meson exchange. Besides a detailed comparison with the total cross section, the discussion focuses on the sensitivity of exclusive ππ angular distributions on relativistic and initial- and final-state corrections.

Pion-pion amplitude from the πN→ ππN reaction

The possibilities of extracting parameters of ππ interaction from the experimental data on the πN→ ππN reaction are analyzed in detail. The interval 300< P lab<500 MeV/ c is shown to be the smoothness domain of the πN→ ππN amplitude. The expression for the background part of the amplitude is developed model-independently. The ππ scattering is described by four parameters to be extracted from experimental data (along with 11 background parameters).

Chiral symmetry and the near threshold pion-induced 2π production on the nucleon: (I). General formalism

The exclusive πN → ππN reaction around the Δ-isobar region provides an excellent testing ground of chiral symmetry. As a first step, a diagrammatical approach to the π −p → π +π −n reaction is formulated based on Weinberg's chiral lagrangian. Tested are the role of various dynamical elements, particularly the significance of nonlinear contributions in the pion field as a signature of chiral symmetry.

ChemInform Abstract: Metal Donor → Metal Acceptor Complexes: Fe(CO)42‐, HFe(CO)4‐, and trans‐ HFe(CO)3P(OMe)3‐ as Anionic Ligands to M(CO)50 , M: Cr, W.

AbstractThe mixed metal binuclear anions are prepared as PPN salts (III) by direct reaction of PPN+ salts of [H Fe(CO)3L′]" (I) with labile THF derivatives (II) of group 6 metal carbonyls photochemically generated.

Übergangsmetall-carbin-komplexe: LXXXIII. Neue anionische mer-dihalogeno-tricarbonyl-dialkylamino-carbin-komplexe des wolframs

The reaction of trans-X(CO) 4WCNR 2 (X = Br, R = c hex (cyclohexyl); X = Cl, R = c hex, ipr (isopropyl) with M +X − (M + = NEt 4 +, X − = Br −; M + = PPN +, X − = Cl −) leads under substitution of one CO ligand to new anionic dihalo(tricarbonyl)carbyne-tungsten complexes of the type M + mer-[(X) 2(CO) 3WCNR 2] − (M + = NEt 4 +, X = Br, R = c hex; M + = PPN +, X = Cl, R = c hex, i pr), whose composition and structure were determined by elemental analysis as well as by IR, 1H and 13C NMR spectroscopy. In the anionic carbyne complexes the entered halogen ligand, coordinated in a cis position relative to the carbyne ligand on the metal, can be easily substituted by neutral nucleophiles, as the reaction of PPN + mer-[(Cl) 2(CO) 3WCN chex 2] − with PPh 3 demonstrates yielding the neutral carbyne complex mer-[Cl(CO) 3(PPh 3)WCN chex 2].

Design and performance of a magnetic spectrometer for the study of πp → ππN reactions near threshold

A measurement of the cross sections of several πp → ππN reaction channels in the region of incident pion momenta of 300 to 460 MeV/ c has been performed with Omicron, a multi-arm magnetic spectrometer of large solid angle. This paper describes the apparatus, the trigger, the readout and data-acquisition systems and the off-line analysis. Sample data illustrating the operation of the apparatus are also presented.

Preparation and properties of acetyliodotricarbonylcobaltate; a novel product from the reaction of methyl iodide with tetracarbonylcobaltate

The reaction of PPN[Co(CO) 4] with an excess of methyl iodide in THF at 0°C gives almost quantitatively PPN[Co(CO) 3{C(O)CH 3})I], which has been shown by X-ray crystallography and spectroscopic measurements to adopt a trigonal bipyramidal structure with three carbonyls in the equatorial plane; it reacts with hydrogen or with sulfuric acid to give acetaldehyde, and with methanol/pyridine to give methyl acetate. The new anion is of interest as a potential intermediate in the cobalt/iodine catalyzed carbonylation or hydrocarbonylation of methanol.

Experimental indications for a 2 ++ non- [formula omitted]q object

Using our high-statistics data from the πp → ππn reaction, we have remade a model-independent partial-wave analysis in finer mass bins at low four-momentum transfer. The Breit-Wigner fits to the leading waves yield m ρ = (777.4 ± 2.0) MeV and Γ ρ = (160 P +4.1 −4.0) MeV, as well as m f = (1273.3 ± 2.3) MeV, Γ f = (179.2 +6.9 −6.6) MeV and x f = (84.9 ± 2.5)%. The last two parameters yield Γ(f → ππ) = (152.1 ± 7.3) MeV, a value which is higher than the one resulting from fits to the decays of the J PC = 2 ++ mesons. On the basis of a smaller discrepancy, Rosner has speculated about a non- q q admixture (possibly gg) in the f(1270), i.e. | f(1270)〉 = | q q 〉 cos θ + | gg〉 sin θ . Repeating his fits with more recent data we obtain a considerably more significant effect with sin 2 θ = 0.18 ± 0.04. This sets a mass of an orthogonal state | f T 〉 = − | q q 〉 sinθ + | gg 〉 cosθ between 1420 and 1620 MeV. The f T could be identified with a 1440 MeV state seen in some K K experiments, A 1 exchange being a possible production mechanism. A fit to our polarized target K +K − data at ∼ 18 GeV/ c yields m(f T) = (1445 +20 −19) MeV and Γ (f T = (81 +52 −25) MeV.