A5075456590- Advanced NMR Techniques and Applications
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Advanced Condensed Matter Physics
- Atomic and Molecular Physics
- Particle accelerators and beam dynamics
- Magnetic and transport properties of perovskites and related materials
- Particle physics theoretical and experimental studies
- Rare-earth and actinide compounds
- Physics of Superconductivity and Magnetism
- Solid-state spectroscopy and crystallography
- Quantum Chromodynamics and Particle Interactions
- Advancements in Battery Materials
- Muon and positron interactions and applications
- NMR spectroscopy and applications
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Particle Accelerators and Free-Electron Lasers
- Mass Spectrometry Techniques and Applications
- Superconducting Materials and Applications
- Crystallography and Radiation Phenomena
- Laser-Plasma Interactions and Diagnostics
- Cold Atom Physics and Bose-Einstein Condensates
- Topological Materials and Phenomena
TRIUMF
2014-2023
Vancouver Biotech (Canada)
2018-2020
Simon Fraser University
1992
Harvard University
1992
We report the observation of weak magnetism in superlattices LaAlO3/SrTiO3 using beta-detected nuclear magnetic resonance. The spin lattice relaxation rate 8 Li with a spacer layers and 6 unit cells LaAlO3 exhibits strong peak near ~35 K, whereas no such is observed superlattice layer thickness 3 cells. attribute temperature dependence to slowing down weakly coupled electronic moments at interface. These results show that interface depends strongly on layer, minimal ~4-6 required for...
Changes in the mean-square nuclear charge radii along lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear light elements are high interest due to appearance halo phenomenon this region chart. During past years we have developed new laser spectroscopic approach determine isotopes which combines sensitivity, speed, accuracy measure extremely small field an 8 ms lifetime with production rates on...
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...
We demonstrate that zero-field $\beta$-detected nuclear quadrupole resonance and spin relaxation of low energy $^8$Li can be used as a sensitive local probe structural phase transitions near surface. find the transition surface SrTiO$_3$ single crystal occurs at $T_c \sim 150$ K, i.e., 45 K higher than $T^{bulk}_c$, tetragonal domains formed below $T_c$ are randomly oriented.
Collinear laser spectroscopy was performed on the nuclear ground states of neutron-deficient isotopes $^{206,205,204}\mathrm{Fr}$. A new technique developed to suppress hyperfine pumping in collinear atoms. This involved high-frequency intensity modulation narrow-linewidth light using fast-switching electro-optical modulators. The ground-state spins $^{206,205,204}\mathrm{Fr}$ were determined be 3, $9/2$, and respectively. Both changes mean-squared charge radii magnetic dipole moments...
Collinear-laser spectroscopy with the bunched-beams technique was used for study of neutron deficient Rb isotopes, out to $^{74}\mathrm{Rb}$ ($N=Z=37$) at TRIUMF. The measured hyperfine coupling constants $^{76,78m}\mathrm{Rb}$ were in agreement literature values. nuclear spin $^{75}\mathrm{Rb}$ confirmed be $I=3/2$, and its first time. mean-square charge radius determined This result has improved isospin symmetry breaking correction term calculate $\mathcal{F}t$ value, implications tests...
We report the NMR Knight shift and spin-lattice relaxation of $^{8}\mathrm{Li}{}^{+}$ implanted $\ensuremath{\sim}100$ nm into single crystals semimetallic Sb, Bi, topologically insulating ${\mathrm{Bi}}_{0.9}{\mathrm{Sb}}_{0.1}$. find small negative shifts (of order 100 ppm) in all three. In insulator, is nearly temperature independent, while Bi Sb it becomes more at low without following bulk susceptibility, suggesting two distinct dependent contributions, possibly from orbital spin...
β-Detected nuclear spin relaxation of (8)Li(+) has been used to study the microscopic diffusion lithium ions in thin films poly(ethylene oxide) (PEO), where implanted are present extremely low concentration, and PEO with 30 wt % LiCF3SO3 over a wide range temperatures both above below glass transition temperature. Recent measurements by Do et al. [Phys. Rev. Lett. 2013, 111, 018301] found that temperature dependence Li(+) conductivity was identical dielectric α well described...
The parity-violating longitudinal analyzing power, Az, has been measured in pp elastic scattering at an incident proton energy of 221 MeV. result obtained is Az =(0.84 +/- 0.29 (stat.) 0.17 (syst.)) x 10^{-7}. This experiment unique that it selects a single parity violating transition amplitude, 3P2-1D2, and consequently directly constrains the weak meson-nucleon coupling constant h^pp_rho When this taken together with existing violation data, constants h^pp_omega can, for first time, both...
A low energy radioactive beam of polarized 8Li has been used to observe the vortex lattice near surface superconducting NbSe2. The inhomogeneous magnetic-field distribution associated with was measured using depth-resolved beta-detected NMR. Below Tc, one observes characteristic line shape for a triangular which depends on magnetic penetration depth and core radius. size varies strongly field. In particular, in field 10.8 mT, radius is much larger than coherence length. possible origin these...
Depth-controlled $\ensuremath{\beta}$-NMR was used to study highly spin-polarized $^{8}\mathrm{Li}^{+}$ in a Cu film of thickness $100\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ deposited onto MgO substrate. The positive Knight shifts and spin relaxation data show that occupies two sites at low temperatures, assigned be the substitutional $(S)$ octahedral $(O)$ interstitial sites. Between 50 $150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, there is site change from $O$ $S$. temperature dependence...
β-detected nuclear spin relaxation of 8Li+ has been used to probe the depth dependence molecular dynamics in high- and low-molecular-weight deuterated polystyrene. The average spin–lattice rate, 1/Tavg1, is a measure spectral density polymer motion at Larmor frequency (41 MHz 6.55 T). In both samples, 1/Tavg1 independent below ∼200 K but above this temperature it decreases approximately exponentially with distance from free surface, returning bulk behavior for depths greater than ∼10 nm....
β-NMR measurements indicate there is enhanced phenyl ring dynamics near the free surface in polystyrene thin films.
TRIUMF experiment 497 has measured the parity-violating longitudinal analyzing power Az in p→p elastic scattering at 221.3 MeV incident proton energy. This comprehensive paper includes details of corrections, some magnitude comparable to itself, required arrive final result. The largest correction was for effects first moments transverse polarization. addition result, Az=[0.84±0.29(stat.)±0.17(syst.)]×10−7, parity-violation experimental data base greatly improves constraints on weak...
A low energy beam of spin polarized $^{8}\text{L}\text{i}$ has been used to investigate nuclear relaxation in the multiband superconductor ${\text{NbSe}}_{2}$. In magnetic fields there is significant cross between and host $^{93}\text{N}\text{b}$ spins, which driven by frequency fluctuations dipolar interaction. The rate strongly field dependent thus $1/{T}_{1}$ a sensitive monitor static local $B$ just below surface. This turn determine absolute value penetration depth...
The $G$-parity-violating, second-class current- (SCC) induced tensor term in the weak-nucleon axial-vector current was determined from $\ensuremath{\beta}$-decay correlation measurements of mass $A$ = 20 mirror pair. alignment terms angular distribution purely spin aligned pair, ${}^{20}$F and ${}^{20}$Na, were measured present study. Combining results with existing $\ensuremath{\beta}$ delayed $\ensuremath{\gamma}$-ray for SCC-induced extracted to be ${d}_{\mathit{II}}/Ac$ 0.18...
A ?-detected nuclear quadrupole resonance (NQR) spectrometer becomes a powerful tool to study changes in ground-state properties along isotopic chains when coupled laser excitation beamline polarize the nuclei of interest. Recently, ?-NQR technique zero magnetic field has been applied for first time measure ratio static moments 8, 9Li, Q9/Q8 = 0.966?75(9) denoted by Q8 8Li and Q9 respectively. This shows agreement with present literature values but significantly improved precision. Based on...
We report results of beta-detected NMR ${^{8}\text{L}\text{i}}^{+}$ implanted in Nb at high magnetic field. identify two distinct sites for $^{8}\text{L}\text{i}$ the body-centered lattice. At low temperature, site is characterized by a well-defined quadrupolar splitting. about 50 K this becomes unstable. Close to room Li occupies cubic substitutional site. Spin-lattice relaxation measurements are consistent with site-dependent coupling conduction electrons and suggest that change proceeds...