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Fantola-Lazzarini, A.L.; Lazzarini, E.; Mariani, Mario

doi:10.1023/a:1022479106226

Cited by 5 publications

(20 citation statements)

References 4 publications

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“…However, subsequent measurements (A.L. Fantola- Lazzarini and Lazzarini, 1990b) led to the expected k Ox value, i.e. zero, within the experimental error (ca.…”

Section: •1supporting

confidence: 65%

“…The effect of inhibitors of Ps formation on the shape of the ACAR curves is obviously similar to that caused by Ps oxidants; indeed inhibitors also increase the intensity of the component of free e f + annihilations at the expense of ortho and para-Ps components. The variation ⌬I p-Ps (c), of I p-Ps (c), is related to the concentration c of reactant by eqn (2•21) (Goldanski, 1968, p. 39) (2•21) (Mn 2+ aq ) are 26.0 ± 1.5 and 1.01 ± 0.06 dm 3 mol -1 ns -1 , respectively (Fantola- Lazzarini and Lazzarini, 1990a).…”

Section: Ps Reaction Types Ascertained By Acar and Dbarl Distributionsmentioning

confidence: 99%

“…The deconvolution is, however, drastically simplified by assuming that ⌬W(p-Ps), ⌬W(o-Ps) and ⌬W(e + f ) are slightly, or not all influenced by solutes, so that they may be considered characteristic constants of the solvent, which may be determined, once and for all, in simplified systems; e.g. ⌬W(e + f ) may be deduced from the AR peak of 5 mol dm -3 NH 4 NO 3 aqueous solutions, where Ps formation is totally inhibited, or of 0•1mol dm -3 KMnO 4 aqueous solution, where the Ps atoms are completed oxidised (Fantola- Lazzarini and Barbaglia, 1994).…”

Section: Energy (Arbitrary Units) Counts (Arbitrary Units)mentioning

confidence: 99%

“…The statement may only be supported a posteriori, but it is surely valid for dilute solutions (≤0•2 mol dm -3 ). A practical description of setting up of a DBARL spectrometer is given in Fantola- Lazzarini and Barbaglia (1994).…”

Section: Energy (Arbitrary Units) Counts (Arbitrary Units)mentioning

confidence: 99%

“…The occurrence of SE reactions may be ascertained by means of the DBARL spectrometry, because the value of the ratio between the intensities of o-Ps and p-Ps components of annihilation radiation peak in solutions of converters decreases compared to that in pure solvent (Section 2•2). As an example see Table 4•4 (Fantola Lazzarini et al, 1998).…”

Section: •2 Spin Exchange Se Reactions Of Ps Atoms 4•2•1 Mechanisms and Probabilities Of Se Reactionsmentioning

confidence: 99%

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REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

Lazzarini

1999

prog. rct. kin. mech.

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The rate constants of oxidation and spin exchange reactions of positronium, Ps, atoms promoted at various temperatures by numerous 3d complexes are reviewed. The experimental methods used in the field are also described. It is shown that the rate constants of Ps oxidation, kOx, and Ps conversion reactions, kCR, may easily be interpreted on the basis of ligand field theory. In particular, values of kCR were found to be linearly correlated with delocalization of unpaired electrons of the metal ions caused by the ligands, as is described by the ratio β between the inter-electronic repulsion parameters in complexes and in the free gaseous ions. The empirical equation used to estimate β seems to work better than previously believed. This should also be considered an achievement of the experiments reviewed. The main conclusion is that, not only may Ps reactions with 3d complexes be easily interpreted by means of ligand field theory, but that the measurements of k for Ps reactions may, reciprocally, constitute a new method for investigating 3d complexes. Evidence was also found that the same conclusions should also be true for reactions of muonium, Mu.

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“…However, subsequent measurements (A.L. Fantola- Lazzarini and Lazzarini, 1990b) led to the expected k Ox value, i.e. zero, within the experimental error (ca.…”

Section: •1supporting

confidence: 65%

Section: Ps Reaction Types Ascertained By Acar and Dbarl Distributionsmentioning

confidence: 99%

Section: Energy (Arbitrary Units) Counts (Arbitrary Units)mentioning

confidence: 99%

Section: Energy (Arbitrary Units) Counts (Arbitrary Units)mentioning

confidence: 99%

Section: •2 Spin Exchange Se Reactions Of Ps Atoms 4•2•1 Mechanisms and Probabilities Of Se Reactionsmentioning

confidence: 99%

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REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

Lazzarini

1999

prog. rct. kin. mech.

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An attempt to apply ligand field theory to positronium reactions with 3d complexes

Lazzarini

2003

Rend. Fis. Acc. Lincei

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Fast Muonium Reactions in Solution: An Electron Spin Exchange Interaction with Cr(NCS)₆^3- in Water and Reaction with Iodine in Organic Solvents

Stadlbauer¹,

Venkateswaran²,

Porter³

et al. 1997

J. Phys. Chem. A

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Two reactions of muonium atoms close to the diffusion-controlled limit were analyzed as a function of solute size and solvent viscosity. With Cr(NCS) 6 3as solute in water, the reaction is an electron spin-conversion process, and the observed rate is taken to be half of the actual encounter rate, because of the quantum mechanical statistical factor and the occurrence of multiple collisions due to the solvent cage effect. The encounter rate deduced is 6.2 × 10 10 M -1 s -1 , which implies a large cross section for the Cr complex. In a second series of experiments, the rate of reaction of muonium with I 2 was compared in water, methanol and n-heptane. The bimolecular rate constants determined are (1.7 ( 0.3), (7.0 ( 1.2), and (57 ( 22) × 10 10 M -1 s -1 , respectively, in these three solvents. This ∼30-fold change in rate is not matched by the change in the inverse of the solvents' viscosities, which changed overall by a factor of only 2.4. It looks as if quantum tunneling dominates over classical diffusion in less polar media where muonium is unencumbered by solvent clathration.

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Cited by 5 publications

References 4 publications

REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

An attempt to apply ligand field theory to positronium reactions with 3d complexes

Fast Muonium Reactions in Solution: An Electron Spin Exchange Interaction with Cr(NCS)₆^3- in Water and Reaction with Iodine in Organic Solvents

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Untitled

Cited by 5 publications

References 4 publications

REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

REACTIVITY OF 3d METAL COMPLEXES TOWARDS POSITRONIUM ATOMS

An attempt to apply ligand field theory to positronium reactions with 3d complexes

Fast Muonium Reactions in Solution: An Electron Spin Exchange Interaction with Cr(NCS)63- in Water and Reaction with Iodine in Organic Solvents

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Fast Muonium Reactions in Solution: An Electron Spin Exchange Interaction with Cr(NCS)₆^3- in Water and Reaction with Iodine in Organic Solvents