107 research outputs found
Quantum point contact conductance in NINS junctions
The effect of an insulating barrier located at a distance from a NS
quantum point contact is analyzed in this work. The Bogoliubov de Gennes
equations are solved for NINS junctions (S: anysotropic superconductor, I:
insulator and N: normal metal), where the NIN region is a quantum wire. For , bound states and resonances in the differential conductance are
predicted. These resonances depend on the symmetry of the pair potential, the
strength of the insulating barrier and . Our results show that in a NINS
quantum point contact the number of resonances vary with the symmetry of the
order parameter. This is to be contrasted with the results for the NINS
junction, in which only the position of the resonances changes with the
symmetry.Comment: 5 pages, 5 Figures, RevTex
Observation of Wigner cusps in a metallic carbon nanotube
Previous gate-dependent conductance measurements of metallic carbon nanotubes
have revealed unexplainable conductance suppressions, occurring at two
different gate voltages. These were previously attributed to the
gate-dependency of contact resistance. Our gate-dependent conductivity
measurements on a metallic nanotube with known chirality show that these
bimodal conductance suppressions are the manifestations of Wigner cusps, often
seen in atomic and nuclear physics experiments.Comment: 6 pages, 3 figure
Uncovering the dominant scatterer in graphene sheets on SiO2
We have measured the impact of atomic hydrogen adsorption on the electronic transport properties of graphene sheets as a function of hydrogen coverage and initial, pre-hydrogenation field-effect mobility. Our results are compatible with hydrogen adsorbates inducing intervalley mixing by exerting a short-range scattering potential. The saturation coverages for different devices are found to be proportional to their initial mobility, indicating that the number of native scatterers is proportional to the saturation coverage of hydrogen. By extrapolating this proportionality, we show that the field-effect mobility can reach 1.5 x 10(4) cm(2)/V s in the absence of the hydrogen-adsorbing sites. This affinity to hydrogen is the signature of the most dominant type of native scatterers in graphene-based field-effect transistors on SiO2
A specific case in the classification of woods by FTIR and chemometric: discrimination of Fagales from Malpighiales
Fourier transform infrared (FTIR) spectroscopic data was used to classify wood samples from nine species within the Fagales and Malpighiales using a range of multivariate statistical methods. Taxonomic classification of the family Fagaceae and Betulaceae from Angiosperm Phylogenetic System Classification (APG II System) was successfully performed using supervised pattern recognition techniques. A methodology for wood sample discrimination was developed using both sapwood and heartwood samples. Ten and eight biomarkers emerged from the dataset to discriminate order and family, respectively. In the species studied FTIR in combination with multivariate analysis highlighted significant chemical differences in hemicelluloses, cellulose and guaiacyl (lignin) and shows promise as a suitable approach for wood sample classification
Spin dependence in the -wave resonance of
We measured the spin dependence in a neutron-induced -wave resonance by
using a polarized epithermal neutron beam and a polarized nuclear target. Our
study focuses on the 0.75~eV -wave resonance state of La+, where
largely enhanced parity violation has been observed. We determined the partial
neutron width of the -wave resonance by measuring the spin dependence of the
neutron absorption cross section between polarized and
polarized neutrons. Our findings serve as a foundation for the quantitative
study of the enhancement effect of the discrete symmetry violations caused by
mixing between partial amplitudes in the compound nuclei
Non-strange Dibaryon Resonances Observed in the Reaction
Coherent double neutral-pion photoproduction on the deuteron,
{}, has been experimentally studied at incident
photon energies ranging from 0.75 to 1.15 GeV. The total cross section as a
function of the center-of-mass energy shows resonance-like
behavior, which peaks at approximately 2.47 and 2.63 GeV. The measured angular
distribution of deuteron emission is rather flat, which cannot be reproduced by
the kinematics of quasi-free production with deuteron coalescence.
In invariant-mass distributions, a clear peak is observed at
GeV with a width of GeV. The
spin-parity of this state is restricted to , or from the
angular distributions of the two s. The present work shows strong
evidence for the existence of an isovector dibaryon resonance with a mass of
2.14 GeV. The assignment is consistent with the theoretically
predicted state, and also with the energy dependence of the
partial-wave amplitude for the
{} and {} reactions.Comment: 12 pages, 6 figure
Effects of Layer Stacking on the Combination Raman modes in Graphene
We have observed new combination modes in the range from 1650 - 2300 cm-1 in
single-(SLG), bi-, few-layer and incommensurate bilayer graphene (IBLG) on
silicon dioxide substrates. The M band at ~1750 cm-1 is suppressed for both SLG
and IBLG. A peak at ~1860 cm-1 (iTALO-) is observed due to a combination of the
iTA and LO phonons. The intensity of this peak decreases with increasing number
of layers and this peak is absent in bulk graphite. Two previously unidentified
modes at ~1880 cm-1 (iTALO+) and ~2220 cm-1 (iTOTA) in SLG are tentatively
assigned as combination modes around the K point of the graphene Brillouin
zone. The peak frequencies of the iTALO+ (iTOTA) modes are observed to increase
(decrease) linearly with increasing graphene layers.Comment: 11 Pages, 4 Figure
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