We experimentally investigate electrical transport properties of graphene, which is a two dimensional (2D) conductor with relativistic energy dispersion relation. By investigating single- and bi-layer graphene devices different aspect ratios, we confirm that the minimum conductivity in wide short strips approaches theoretical value 4e^2/\pi\h. At low temperatures, quantum interference multiply-reflected waves electrons holes give rise to periodic conductance oscillations bias gate voltages....

We report experiments on quantum dot single-electron-tunneling (SET) transistors made from short multiwall nanotubes and threaded by magnetic flux. Such systems allow us to probe the electronic energy spectrum of nanotube its dependence field. Evidence is provided for interconversion between gapped (semiconducting) ungapped (metallic) states. Our tubes exhibit h/e-period flux dependence, in agreement with simple tight-binding calculations.

We study the stochastic nature of switching current in hysteretic current-voltage characteristics superconductor-graphene-superconductor junctions. find that dispersion distribution scales with temperature as σ(I) proportional to T(α(G)) α(G) low 1/3. This observation is sharp contrast known Josephson junction behavior where T(α(J)) α(J)=2/3. propose an explanation using a generalized version Kurkijärvi's theory for flux stability rf-SQUID and attribute this anomalous effect dependence...

We examine the nature of transitions between normal and superconducting branches in superconductor-graphene-superconductor Josephson junctions. attribute hysteresis switching (superconducting to normal) retrapping (normal superconducting) electron overheating. In particular, we demonstrate that current corresponds critical at an elevated temperature, where heating is caused by itself. The gap leads suppresses hot outflow, allowing us further study thermalization phonons low temperatures (T≲1...

We report on graphene-based Josephson junctions with contacts made from lead. The high transition temperature of this superconductor allows us to observe the supercurrent branch at temperatures up $\sim 2$ K, which point we can detect a small, but non-zero, resistance. attribute resistance phase diffusion mechanism, has not been yet identified in graphene. By measuring as function and gate voltage, further characterize nature electromagnetic environment dissipation our samples.

We describe a method to pattern SiO2 surfaces with colloidal gold nanoparticles by e-beam lithography and selective nanoparticle deposition. The simple technique allows us deposit in continuous straight lines, just one wide many long. contact the prepositioned metal leads form single electron transistors. Coulomb blockade surprisingly does not show parasitic “offset charges” at low temperatures, indicating relatively little surface contamination.

We perform measurements of phase-slip-induced switching current events on different types superconducting weak links and systematically study statistical properties the distributions. employ two devices in which a link is formed either by nanowire or graphene flake subject to proximity effect. demonstrate that, independently nature link, higher moments distribution take universal values. In particular, third moment (skewness) close -1 both thermal quantum regimes. The fourth (kurtosis) also...

We fabricate superconductor-graphene-superconductor Josephson junctions with superconducting regions made of lead (Pb). The critical current through grapehene may be modulated by external magnetic field; the resulting Fraunhofer interference pattern shows several periods oscillations, indicating that junction is uniform. Deviations from perfect are observed, and their cause explained a simulation takes into account sample design.

Stimulated emission depletion (STED) microscopy is a powerful super-resolution technique that enables observation of macromolecular complexes and sub-cellular structures with spatial resolution below the diffraction limit. The STED limited by power laser at specimen plane. Higher will improve resolution, but cost increased photo-bleaching, photo-toxicity, anti-stoke background. This degrades signal-to-noise ratio, can significantly limit applications in living specimens. Here, we present an...

Multiplexed fluorescence detection has become an indispensable tool in modern biosensing and imaging. Although a variety of excitation/detection optics designs unmixing schemes have been proposed to achieve multiplexed detection, successful differentiation quantification multiple fluorophores at each imaging pixel is still challenging. Recently, lifetime microscopy (FLIM) combination with the phasor plot analysis shown many advantages over other methods. Being intrinsic property fluorescent...

Photoluminescence (PL) refers to light emission initiated by any form of photon excitation. PL spectroscopy and microscopy imaging has been widely applied in material, chemical life sciences. Measuring its lifetime yields a new dimension the opens opportunities for many applications. In solar cell research, quantification become an important evaluation characteristics Perovskite thin film. Depending upon process (fluorescence, phosphorescence, upconversion, etc.), lifetimes be measured can...

The crosstalk between two fluorescent species causes problems in fluorescence microscopy imaging, especially for quantitative measurements such as co-localization, Förster resonance energy transfer (FRET), cross correlation spectroscopy (FCCS). In laser scanning confocal microscopy, the lasers can be switched on and off by acousto-optic tunable filters (AOTF) microsecond scale alternative line order to avoid while minimizing time delay same pixel location. contrast, pulsed interleaved...

Stimulated emission depletion (STED) microscopy is a powerful super-resolution technique that enables observation of sub-cellular structures with spatial resolution well below the diffraction limit. The higher STED beam intensity, resolution, but at cost increased photo-damage, which significantly limits application in live specimens. separation by lifetime tuning (SPLIT) uses time-resolved acquisition and phasor-based analysis to efficiently distinguish photons emitted from center periphery...

The effect of purification on room temperature electronic transport properties single-wall nanotubes (SWNT) was studied by submerging the into liquid mercury. conductance plots purified SWNTs showed plateaus, indicating weak dependence electrical resistance length tube connecting electrodes, providing evidence quasiballistic conduction in SWNTs. mean free path reached a few microns, which is longer than that as-produced SWNTs, and consistent with calculation based scattering acoustic phonons.

Phosphorescence probes can have significantly long lifetimes, on the order of micro- to milli-seconds or longer. In addition, environmental changes affect lifetimes these phosphorescence probes. Thus, Lifetime Imaging Microscopy (PLIM) is a very useful tool localize based their study variance in due micro changes. Since respond biologically relevant parameters like oxygen concentration, they be used various processes cellular metabolism, protein interaction etc. this case, we effects Oxyphor...

PIE FastFLIM microscopy allows the quantitative multi-parameter measurement of single molecule protein folding and dynamics. Using donor-acceptor FRET pair-labeled proteins, we detect changes in conformation dynamics by monitoring efficiency, stoichiometry lifetime. Together with anisotropy decay information, acquire rotational relaxation times for molecules. By applying antibunching, FLCS burst analysis, multi-parameters (such as copy numbers complexes), diffusion coefficient molecular...

We present a microscopy technique, orbital particle tracking, in which the scanner scans orbits around species, unlike raster imaging technique an area one line at time. By analyzing fluorescence emission intensity variation along orbit, location of species orbit can be determined with precision tenth nanometer millisecond time scale, and moved to new through feedback loop if any movement is detected. This extended two scanning orbits, above below sample plane track 3D space. It used vitro...

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique that provides totally new dimension to quantitate the fluorescent probe, in addition its steady-state intensity and spectral profiles. As fluorescence parameter specific of each fluorophore, measurement instrumental identification fluorophore mixture: this opens opportunity for multiplex improves sensitivity (signal-to-noise ratio) resolution many applications. More importantly, with peculiar selectivity probes, FLIM can...