A5029880137- Muon and positron interactions and applications
- Ammonia Synthesis and Nitrogen Reduction
- Advanced NMR Techniques and Applications
- Advanced Chemical Physics Studies
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Inorganic Fluorides and Related Compounds
- Particle Detector Development and Performance
- Magnetic Properties of Alloys
- Hydrogen Storage and Materials
- Graphene research and applications
- Quantum, superfluid, helium dynamics
- Particle accelerators and beam dynamics
- Particle physics theoretical and experimental studies
- Iron-based superconductors research
- Advancements in Battery Materials
- Chemical Synthesis and Characterization
- Inorganic Chemistry and Materials
- Chemical Reactions and Isotopes
- Catalytic Processes in Materials Science
- Solid-state spectroscopy and crystallography
TRIUMF
2014-2024
Vancouver Biotech (Canada)
2020
University of British Columbia
1999-2015
Trimble (Germany)
2012
Mount Allison University
2008
Simon Fraser University
2008
University of Alberta
2007
Canadian Institute for Advanced Research
1999
The neutral muonic helium atom may be regarded as the heaviest isotope of hydrogen atom, with a mass ~4.1 atomic units ((4.1)H), because negative muon almost perfectly screens one proton charge. We report reaction rate (4.1)H (1)H(2) to produce (4.1)H(1)H + (1)H at 295 500 kelvin. experimental constants are compared predictions accurate quantum-mechanical dynamics calculations carried out on an Born-Huang potential energy surface and previously measured (0.11)H (where is shorthand for...
Depth-controlled $\ensuremath{\beta}$-NMR can be used to probe the magnetic properties of thin films and interfaces on a nanometer length scale. A 30 keV beam highly spin-polarized $^{8}\mathrm{L}\mathrm{i}^{+}$ ions was slowed down implanted into 50 nm film Ag deposited ${\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}$ substrate. novel high field spectrometer observe two well resolved resonances which are attributed Li occupying substitutional octahedral interstitial sites in...
Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with hydrogen and deuterium—Mu+H2→MuH+H Mu+D2→MuD+D—over temperature range 473–843 K are reported. The Arrhenius parameters 1σ uncertainties H2 reaction log A (cm3 molecule−1 s−1)=−9.605±0.074 Ea =13.29±0.22 kcal mol−1, while D2 values −9.67±0.12 14.73±0.40, respectively. These results significantly more precise than those reported earlier by Garner et al. For Mu our in excellent agreement 3D quantum mechanical...
The thermally averaged depolarization cross sections, \ensuremath{\sigma}${\ifmmode\bar\else\textasciimacron\fi{}}_{D}$(T), for Mu+${\mathrm{O}}_{2}$ electron spin exchange, have been measured by the muon relaxation (\ensuremath{\mu}SR) technique in a ${\mathrm{N}}_{2}$ moderator at total pressures near 1 atm over temperature range 88--500 K. These values are related to thermal spin-flip sections of interest (\ensuremath{\sigma}${\ifmmode\bar\else\textasciimacron\fi{}}_{\mathrm{SF}}$) simple...
The neutral muonic helium atom (4)Heμ, in which one of the electrons He is replaced by a negative muon, may be effectively regarded as heaviest isotope hydrogen atom, with mass 4.115 amu. We report details first muon spin rotation (μSR) measurements chemical reaction rate constant (4)Heμ molecular hydrogen, + H(2) → (4)HeμH H, at temperatures 295.5, 405, and 500 K, well μSR measurement hyperfine coupling high pressures. experimental constants, k(Heμ), are compared predictions accurate...
The rate constant for the H atom abstraction reaction from methane by muonic helium atom, Heμ + CH4 → HeμH CH3, is reported at 500 K and compared with theory, providing an important test of both potential energy surface (PES) theory prototypical polyatomic CH5 system. used to characterize this includes variational transition-state (CVT/μOMT) (VTST) ring polymer molecular dynamics (RPMD) calculations on a recently developed PES, which are as well earlier different PESs H, D, Mu reactions,...
We report muon spin rotation measurements in $n$-type silicon from 10 to 310 K electric fields up 5 kV/cm. These experiments reveal the nature of partition neutral muonium centers into normal $({\mathrm{Mu}}_{T}^{0})$ and anomalous $({\mathrm{Mu}}_{\mathrm{BC}}^{0})$: Formation ${\mathrm{Mu}}_{T}^{0}$ is consistent with epithermal processes prior thermalization, while ${\mathrm{Mu}}_{\mathrm{BC}}^{0}$ formed via electron transport a thermalized positive muon. The spatial distribution excess...
Muon spin relaxation/rotation/resonance ( $$\varvec{\mu \textrm{SR}}$$ ) method is one of the most effective experimental methods and has been used in many fields such as material science, chemical, bioscience since 1970s. For next elevation , we developed positron detectors that have a spatial resolution them trackers so could construct an image sample. Demonstrative experiments were performed at TRIUMF sample was successfully reconstructed.
Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with halogen gases—Mu+X2→MuX+X—are reported over temperature ranges from 500 down to 100, 160, and 200 K X2=F2,Cl2, Br2, respectively. The Arrhenius plots both chlorine fluorine show positive activation energies Ea whole studied, but which decrease near zero at low temperature, indicative dominant role played by quantum tunneling ultralight atom. In case Mu+F2, bimolecular constant k(T) is essentially independent...
Experiments reveal muon-polaron complexes in Cr${}_{2}$O${}_{3}$. Similar entities may exist many magnetic insulators and semiconductors, where they can be used as proxies to understand the impact of hydrogen impurities.
The spin relaxation of the muonium-substituted ethyl radical (MuCH2ĊH2) and its deuterated analog (MuCD2ĊD2) has been studied in gas phase both transverse longitudinal magnetic fields spanning range ∼0.5–35 kG, over a pressure from ∼1–16 atm at ambient temperature. Mu13CH213ĊH2 also investigated, 2.7 atm. For comparison, some data is reported for MuCH2Ċ(CH3)2 (Mu-t-butyl) 2.6 This experiment establishes importance μSR technique studying phenomena polyatomic radicals phase, where equivalent...
The reaction kinetics for the addition of muonium (Mu=μ+e−) atom to C2H4 and C2D4 have been measured over temperature range 150–500 K at (N2) moderator pressures near 1 atm. A factor about 8 variation in pressure was carried out C2H4, with no significant change seen apparent rate constant kapp, which is therefore taken be high limit, yielding bimolecular kMu step. This also expected from nature μSR technique employed, which, favorable cases, gives kapp=kMu any pressure. Comparisons H data...
Muon spin rotation/relaxation measurements show clear evidence for magnetism in 2.2 nm gold nanoparticles capped with butanethiol. At low temperatures (1.8 K), there is significant relaxation which decreases as a function of both the applied longitudinal magnetic field and increasing temperature. The results indicate that are spatially inhomogeneous electronic moments fluctuate wide distribution correlation times. Possible explanations discussed.
We perform detailed muon spin rotation ($\ensuremath{\mu}\mathrm{SR}$) measurements in the classic antiferromagnet ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ and explain spectra by considering dynamic population dissociation of charge-neutral muon-polaron complexes. show that states ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$, despite lacking signatures typical muonium centers nonmagnetic materials, have a significant impact on measured $\ensuremath{\mu}\mathrm{SR}$ frequencies relaxation rates. Our...
The times taken by positive muons $({\ensuremath{\mu}}^{+})$ to slow down from initial energies in the range $\ensuremath{\sim}3$ $1\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$, energy of last muonium formation, $\ensuremath{\approx}10\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, at end cyclic charge exchange, have been measured pure gases ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, $\mathrm{Ar}$, and gas mixtures $\mathrm{Ar}\text{\ensuremath{-}}\mathrm{He}$,...
Chemisorption of muonium onto the surface gold nanoparticles has been observed. Muonium (μ+e−), a light hydrogen-like atom, reacts chemically with uncapped 7 nm embedded in mesoporous silica (SBA-15) strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into diamagnetic muon state on nanoparticle surface. well established as sensitive probe static or slowly fluctuating magnetic fields bulk matter. These results represent first rotation signal any...
<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>β</a:mi></a:math>-Mn-type family alloys <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:msub><b:mi>Mn</b:mi><b:mn>3</b:mn></b:msub><b:mrow><b:mi>T</b:mi><b:mi>X</b:mi></b:mrow></b:mrow></b:math> (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mi>T</c:mi><c:mo>=</c:mo><c:mtext>Co</c:mtext></c:mrow></c:math>, Rh, and Ir; <d:math...
The muon spin rotation/relaxation/resonance ( $$\varvec{\mu }$$ SR) spectroscopy is widely used as a unique tool for probing magnetic properties in materials. We aim to enhance this method by incorporating imaging functionality. In study, we conducted an experiment using new device that utilizes positron tracking from decays assess the reliability of and its positional resolution. As result, have demonstrated image depicting hole with diameter 5 mm could be reconstructed.
Rates for the gas-phase thermal reaction Mu+CH4→MuH+CH3 (Mu=μ+e−), have been measured using μSR (muon spin rotation) technique, over temperature range 625–820 K. A good fit is obtained to usual Arrhenius expression, k=A exp(−Ea/RT), giving an activation energy Ea=24.6±0.9 kcal/mol, ∼12 kcal/mol higher than that of H-atom isotopic variant this reaction, H+CH4→H2+CH3. This Ea difference largest yet seen at high temperatures between H and Mu in gas phase, seems much too be explained terms...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMuonium formation in vaporsDonald J. Arseneau, David M. Garner, Masayoshi Senba, and Donald G. FlemingCite this: Phys. Chem. 1984, 88, 16, 3688–3696Publication Date (Print):August 1, 1984Publication History Published online1 May 2002Published inissue 1 August 1984https://pubs.acs.org/doi/10.1021/j150660a063https://doi.org/10.1021/j150660a063research-articleACS PublicationsRequest reuse permissionsArticle Views56Altmetric-Citations22LEARN ABOUT...
Muon spin-rotation experiments (supported by magnetization measurements) have been carried out in the canonical $4f$ mixed-valence narrow-gap semiconductor SmS from 10 to 900 K magnetic fields up 3.5 T. A bound state of an electron around a positive muon is found form about 800 K. This polaron: wave function confined within $R\ensuremath{\approx}0.5\text{ }\text{nm}$ (the first two coordination spheres) due its exchange interaction with Sm moments. As such, it may serve as model system for...