Showing papers by "Emil Roduner published in 1997"
TL;DR: In this article, the evolution of muon spin polarization rests on the same basis as in conventional magnetic resonance techniques, and different variants of the experimental set-up, and potential and limitations of the muon as a probe are described.
Abstract: Spin polarized positive muons injected in matter serve as magnetic probes for the investigation of various properties. The evolution of muon spin polarization rests on the same basis as in conventional magnetic resonance techniques. The background of the technique, different variants of the experimental set-up, and potential and limitations of the muon as a probe are described.
49 citations
TL;DR: In this article, the dynamics of the muonium substituted cyclohexadienyl radical adsorbed on silicalite and NaZSM•5 was investigated by means of avoided level crossing muon spin resonance.
Abstract: The dynamics of the muonium substituted cyclohexadienyl radical adsorbed on silicalite and NaZSM‐5 is investigated by means of avoided level crossing muon spin resonance. The influence of benzene loading on the mobility of the radical is studied. At low loadings the radicals were found to be located on a single adsorption site where they undergo a wobbling type of motion. With increasing loading an additional species adsorbed on a different site is observed.
13 citations
TL;DR: In this paper, the ALC μSR spectra of the muonated ethyl and cyclohexadienyl radicals in the gas phase were reported, and they have surprisingly narrow lines for a magnetic resonance type technique under conditions near ambient temperature and near 1 atmosphere pressure.
Abstract: ALC μSR spectra of the muonated ethyl and cyclohexadienyl radicals in the gas phase are reported. They have surprisingly narrow lines for a magnetic resonance type technique under conditions near ambient temperature and near 1 atmosphere pressure. The main reason for this behaviour is the dramatic reduction of electron spin relaxation in high magnetic fields.
13 citations
01 Jun 1997
TL;DR: In this article, the authors used the muon spin relaxation technique in longitudinal magnetic fields to investigate the kinetics of the addition reaction of O 2 to the tert-butyl radical.
Abstract: The kinetics of the addition reaction of O 2 to the tert-butyl radical has been investigated at 1.5 bar as a function of temperature (241 -462 K) using the muon spin relaxation technique in longitudinal magnetic fields. The data are represented by k Ch = 43 - + 26 88 x 10 -10 T -0.96 ± 0.21 cm 3 molecules -1 s -1 , or alternatively by an Arrhenius activation energy of -2.4(0.7)kJmol -1 and an apparent frequency factor of 68(19)x10 -13 cm 3 molecules -1 s -1 . The results of these temperature-dependent measurements agree well with an experimental literature value at room temperature, but disagree with a more recent estimate by a factor of six.
12 citations
TL;DR: In this paper, the transverse field muon spin rotation (TF•μSR) technique was used to detect the presence of radicals in liquid samples of nitroalkanes, detectable by small hyperfine couplings (ca. 26 MHz).
Abstract: Implantation of positive muons in liquid samples of nitroalkanes leads to radicals, detectable by the transverse field muon spin rotation (TF‐μSR) technique, with small hyperfine couplings (ca. 26 MHz). The results indicate that muonium has added to one of the oxygen atoms of the nitro group and that the bound muon remains close to the ‘nodal’ region of the nitrogen 2pz orbital, which contributes to the SOMO. This is a consequence of π‐bonding in the O—N—O(Mu) unit, which is maximally preserved. An abrupt change is found for the nitrobenzene adduct, in which the coupling is raised to 37.14 MHz. Semi‐empirical (PM3) calculations provide an explanation for this in terms of the different geometries of RNO2H· and PhNO2H· radicals, the former being bent at the nitrogen centre while PhNO2H· is planar. When PhNO2H· is located in NaX zeolite, its coupling is increased; this is thought to be due to the electrostatic field from Na+ cations. © 1997 John Wiley & Sons, Ltd.
4 citations