A5068563983- Physics of Superconductivity and Magnetism
- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Advanced Condensed Matter Physics
- Magnetic properties of thin films
- Atmospheric Ozone and Climate
- Copper-based nanomaterials and applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Muon and positron interactions and applications
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Surface Modification and Superhydrophobicity
- Plasmonic and Surface Plasmon Research
- Superconductivity in MgB2 and Alloys
- Magnetic and transport properties of perovskites and related materials
- Adhesion, Friction, and Surface Interactions
- Superconducting Materials and Applications
- Rare-earth and actinide compounds
- Terahertz technology and applications
- Porphyrin and Phthalocyanine Chemistry
- Atmospheric aerosols and clouds
- Advanced Photocatalysis Techniques
- Diffusion Coefficients in Liquids
- Luminescence and Fluorescent Materials
- Quantum and electron transport phenomena
University of British Columbia
2016-2025
Egyptian Petroleum Research Institute
2024
Simon Fraser University
2004-2023
Institute of Chemistry, Academia Sinica
2023
Amirkabir University of Technology
2020
A large fraction of submicron atmospheric aerosol particles contains both organic material and inorganic salts. As the relative humidity cycles in atmosphere water content correspondingly changes, these mixed can undergo a range phase transitions, possibly including liquid–liquid separation. If separation occurs, gas-particle partitioning semivolatile compounds, scattering absorption solar radiation, reactive uptake gas species on may be affected, with important implications for climate...
This paper introduces a new approach to measure the muon magnetic moment anomaly |$a_{\mu} = (g-2)/2$| and electric dipole (EDM) |$d_{\mu}$| at J-PARC facility. The goal of our experiment is |$a_{\mu}$| using an independent method with factor 10 lower momentum, 20 smaller diameter storage-ring solenoid compared previous ongoing |$g-2$| experiments unprecedented quality storage field. Additional significant differences from present experimental include 1000 transverse emittance beam...
A set of highly sensitive cavity perturbation techniques, quite different from the ones most commonly used to measure thin films, has been developed for measuring surface impedance small crystals high-${\mathit{T}}_{\mathit{c}}$ superconductors. Since results these studies differ markedly surface-impedance measurements films superconductors, we describe techniques in detail, including recent improvements. Measurements resistance and penetration depth a twin-free crystal...
We report measurements of the electromagnetic penetration depth $\ensuremath{\lambda}(T)$ in nominally pure crystals ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6,95}$, for temperatures close to critical temperature ${T}_{c}$. Over range $\frac{0.001<({T}_{c}\ensuremath{-}T)}{{T}_{c}<0.1}$, we find that $\ensuremath{\lambda}(T)\ensuremath{\propto}{(\frac{1\ensuremath{-}T}{{T}_{c}})}^{\ensuremath{-}y}$ with $y\ensuremath{\approx}0.33$, consistent behavior three dimensional...
We present here the microwave surface impedance of a high-purity crystal ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.99}$ measured at five frequencies between 1 and 75 GHz. This data set reveals main features conductivity spectrum thermally excited quasiparticles in superconducting state. Below 20 K there is regime extremely long quasiparticle scattering times, due to both collapse inelastic below ${T}_{c}$ very weak impurity ${\mathrm{BaZrO}}_{3}$-grown used this study. Above K,...
This work studies in detail the effect of femtosecond laser irradiation process parameters (fluence and scanning speed) on hydrophobicity resulting micro/nano-patterned morphologies stainless steel. Depending parameters, four distinctly different nano-patterns were produced, namely nano-rippled, parabolic-pillared, elongated sinusoidal-pillared triple roughness nano-structures. All produced structures classified according to a newly defined parameter, intensity factor (LIF); by increasing...
The temperature dependence of the surface resistance ${R}_{s}$, and penetration depth $\ensuremath{\lambda}$ has been measured in both $a$ $b$ directions ${\mathrm{Yba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.95}$. overall dependences are similar show a linear behavior at low $T$. This argues against chains playing direct role unconventional impedance. residual ${R}_{s}$ these twin-free crystals is very small, implying conductivity order minimum value predicted by Lee Phys. Rev. Lett. 71...
Abstract A femtosecond laser was used to create microstructures on very pure metal surfaces. The irradiated samples initially showed super-hydrophilic behavior. With time and exposure ambient air the contact angle increased about 160° with low hysteresis. surfaces supported Cassie Wenzel wetting states, depending technique deposit water droplets. created surface morphologies were idealized a geometric model that is an assembly of densely packed cylindrical pillars semispherical caps. Using...
Abstract. Knowledge of the viscosity particles containing secondary organic material (SOM) is useful for predicting reaction rates and diffusion in SOM particles. In this study we investigate as a function relative humidity particle mass concentration, during synthesis. The was generated via ozonolysis α-pinene at < 5 % (RH). Experiments were carried out using poke-and-flow technique, which measures experimental flow time (τexp, flow) after poking with needle. first set experiments, show...
Abstract Near‐infrared‐emitting polymers were prepared using four boron‐difluoride‐curcuminoid‐based monomers ring‐opening metathesis polymerization (ROMP). Well‐defined with molecular weights of ≈20 kDa and dispersities <1.07 produced exhibited near‐infrared (NIR) emission in solution the solid state photoluminescence quantum yields (Φ PL ) as high 0.72 0.18, respectively. Time‐resolved spectroscopy revealed thermally activated delayed fluorescence (TADF) containing highly planar...
Energy transfer (EnT) is a fundamental activation process in visible-light-promoted photocycloaddition reactions. This work describes the performance of imidazoacridine-based TADF materials for visible-light mediated triplet-triplet EnT photocatalysis. The material ACR-IMAC has been discovered as an inexpensive, high-performance organic alternative to commonly used metal-based photosensitizers efficiency photosensitizer comparable with Ir-based both intra- and intermolecular [2 + 2]...
Pendant organic chromophores have been used to improve the photocatalytic performance of many metal-based photosensitizers, particularly in first-row metals, by increasing π conjugation ligands and lowering energy photoactive absorption band. Using a combination spectroscopic studies computational modeling, we rationalize excited state dynamics Co(III) complex containing pendant pyrene moieties, CoL1, where L1 = 1,1′-(4-(pyren-1-yl)pyridine-2,6-diyl)bis(3-methyl-1H-imidazol-3-ium). CoL1...
Abstract. The diffusion coefficients of organic species in secondary aerosol (SOA) particles are needed to predict the growth and reactivity these atmosphere. Previously, viscosity measurements, along with Stokes–Einstein relation, have been used estimate rates organics within SOA or proxies particles. To test we measured three fluorescent dyes (fluorescein, rhodamine 6G calcein) sucrose–water solutions varying water activity. Sucrose–water were as a proxy for material found Diffusion using...
Abstract. Information on the rate of diffusion organic molecules within secondary aerosol (SOA) is needed to accurately predict effects SOA climate and air quality. Diffusion can be important for predicting growth, evaporation, reaction rates under certain atmospheric conditions. Often, researchers have predicted using measurements viscosity Stokes–Einstein relation (D∝1/η, where D coefficient η viscosity). However, accuracy this in remains uncertain. Using rectangular area fluorescence...
We have succeeded in growing very high-purity (99.995%) ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ crystals ${\mathrm{BaZrO}}_{3}$ crucibles and measured $\ensuremath{\Delta}\ensuremath{\lambda}(T)$ ${R}_{s}(T)$ at 1 GHz with various oxygen treatments. For an vacancy level of $\ensuremath{\delta}=0.007,$ \ensuremath{\Delta}\ensuremath{\lambda} ${R}_{s}$ essentially reproduce our previous results show no sign the existence two...
Diffusion coefficients in mixtures of organic molecules and water are needed for many applications, ranging from the environmental modeling pollutant transport, air quality, climate, to improving stability foods, biomolecules, pharmaceutical agents longer use storage. The Stokes–Einstein relation has been successful predicting diffusion large organic–water viscosity, yet it routinely underpredicts, by orders magnitude, small mixtures. Herein, a unified description mixtures, based on...
Semiconducting polymer dots (Pdots) have emerged as versatile probes for bioanalysis and imaging at the single-particle level. Despite their utility in multiplexed analysis, deep blue Pdots remain rare due to need high-energy excitation sensitivity photobleaching. Here, we describe design of fluorophores using structural constraints improve resistance photobleaching, two-photon absorption cross sections, fluorescence quantum yields hexamethylazatriangulene motif. Scanning tunneling...
Smoke particles generated by burning biomass consist mainly of organic aerosol termed (BBOA). BBOA influences the climate scattering and absorbing solar radiation or acting as nuclei for cloud formation. The viscosity phase behavior (i.e., number type phases present in a particle) are properties that expected to impact several climate-relevant processes but remain highly uncertain. We studied using fluorescence microscopy showed comprise two (a hydrophobic hydrophilic phase) across wide...
We describe an in situ-polymerized conformal thin layer coating of narrow band gap carbon-rich carbon nitride (NBG-CRCN) on titania nanorod arrays to design a binary semiconductor heterojunction photocatalyst. The situ polymerization creates strong interaction between the TiO2 substrate and film, which prevents leaching CRCN liquid electrolytes. A unique aspect our work is developing easy inexpensive technique for heteroepitaxial growth mechanically photochemically stable films with intimate...
New measurements of surface impedance in ybco show that the c-axis penetration depth and conductivity below Tc exhibit behaviour different from observed planes. The never has linear temperature dependence seen ab-plane. Instead peak planes, microwave falls to low values superconducting state, then rises slightly 20K. These results transport remains incoherent Tc, even though this is one least anisotropic cuprate superconductors.
Nanophotonics research has focused recently on the ability of nonlinear optical processes to mediate and transform signals in a myriad novel devices, including modulators, transducers, color filters, photodetectors, photon sources, ultrafast switches. The inherent weakness nonlinearities at smaller scales has, however, hindered realization efficient miniaturized strategies for enhancing both device efficiencies synthesis throughput via nanoengineering remain limited. Here, we demonstrate...
There has long been a discrepancy between microwave conductivity measurements in high temperature superconductors and the spectrum expected simplest models for impurity scattering d-wave superconductor. Here we present new type of broadband measurement surface resistance that finally shows some spectral features d(x2-y2) pairing state. Cusp-shaped spectra, consistent with weak nodal quasiparticles, were obtained 0.6-21 GHz frequency range highly ordered crystals YBa2Cu3O6.50 YBa2Cu3O6.99.