777 research outputs found
Electronic, magnetic and transport properties of Fe intercalated 2H-TaS studied by means of the KKR-CPA method
The electronic, magnetic and transport properties of Fe intercalated
2H-TaS have been investigated by means of the Korringa-Kohn-Rostoker (KKR)
method. The non-stoichiometry and disorder in the system has been accounted for
using the Coherent Potential Approximation (CPA) alloy theory. A pronounced
influence of disorder on the spin magnetic moment has been found for the
ferro-magnetically ordered material. The same applies for the spin-orbit
induced orbital magnetic moment and magneto-crystalline anisotropy energy. The
temperature-dependence of the resistivity of disordered 2H-FeTaS
investigated on the basis of the Kubo-St\v{r}eda formalism in combination with
the alloy analogy model has been found in very satisfying agreement with
experimental data. This also holds for the temperature dependent anomalous Hall
resistivity . The role of thermally induced lattice
vibrations and spin fluctuations for the transport properties is discussed in
detail
Electronic structure and magnetic properties of CrSb and FeSb investigated via ab-initio calculations
The electronic structure and magnetic properties of CrSb have been
investigated by ab-initio calculations with an emphasis on the role of the
magnetic structure for the ground state. The influence of correlation effects
has been investigated by performing fixed spin moment (FSM) calculations
showing their important role for the electronic and magnetic properties. The
details of the electronic structure of CrSb are analyzed by a comparison
with those of FeSb. The results obtained contribute in particular to the
understanding of the temperature dependence of transport and magnetic behavior
observed experimentally
Determination of Benzene, Toluene, and Xylene by means of an ion mobility spectrometer device using photoionization
The continuous monitoring of changes on the quality of ambient air is a field of advantage of ion mobility spectrometry. Benzene, Toluene, and Xylene are substances of special interest because of their toxicity. We present an optimized drift tube for ion mobility spectrometers, which uses photo-ionization tubes to produce the ions to be analyzed. The actual version of this drift tube has a length of 45 mm, an electric field strength established within the drift tube of about 180 V/cm and a shutter-opening-time of 400 mus. With the hydrogen tube used for ionisation a mean flux of 10(exp 12) photons/sq cm s was established for the experiments described. We discuss the results of investigations on Benzene, Toluene, and Xylene in normal used gasoline SUPER. The detection limits obtained with the ion mobility spectrometer developed in co-operation are in the range of 10 ppbv in this case. Normally, charge transfer from Benzene ions to Toluene takes place. Nevertheless the simultaneous determination in mixtures is possible by a data evaluation procedure developed for this case. The interferences found between Xylene and others are rather weak. The ion mobility spectra of different concentrations of gasoline SUPER are attached as an example for the resolution and the detection limit of the instrument developed. Resolution and sensitivity of the system are well demonstrated. A hand-held portable device produced just now is to be tested for special environmental analytical problems in some industrial and scientific laboratories in Germany
CuCoS Deposited on TiO: Controlling the pH Value Boosts Photocatalytic Hydrogen Evolution
Metallic spinel-type CuCoS nanoparticles were deposited on nanocrystalline TiO (P25®), forming heterostructure nanocomposites. The nanocomposites were characterized in detail by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), nitrogen sorption (BET) and UV/Vis spectroscopy. Variation of the CuCoS:TiO ratio to an optimum value generated a catalyst which shows a very high photocatalytic H production rate at neutral pH of 32.3 µmol/h (0.72 mLh), which is much larger than for pure TiO (traces of H). The catalyst exhibits an extraordinary long-term stability and after 70 h irradiation time about 2 mmol H were generated. An increased light absorption and an efficient charge separation for the sample with the optimal CuCoS:TiO ratio is most probably responsible for the high catalytic activity
Deep Einstein@Home All-sky Search for Continuous Gravitational Waves in LIGO O3 Public Data
We present the results of an all-sky search for continuous gravitational waves in the public LIGO O3 data. The search covers signal frequencies 20.0 Hz ≤ f ≤ 800.0 Hz and a spin-down range down to −2.6 × 10−9 Hz s−1, motivated by detectability studies on synthetic populations of Galactic neutron stars. This search is the most sensitive all-sky search to date in this frequency/spin-down region. The initial search was performed using the first half of the public LIGO O3 data (O3a), utilizing graphical processing units provided in equal parts by the volunteers of the Einstein@Home computing project and by the ATLAS cluster. After a hierarchical follow-up in seven stages, 12 candidates remain. Six are discarded at the eighth stage, by using the remaining O3 LIGO data (O3b). The surviving six can be ascribed to continuous-wave fake signals present in the LIGO data for validation purposes. We recover these fake signals with very high accuracy with our last stage search, which coherently combines all O3 data. Based on our results, we set upper limits on the gravitational-wave amplitude h 0 and translate these into upper limits on the neutron star ellipticity and on the r-mode amplitude. The most stringent upper limits are at 203 Hz, with h 0 = 8.1 × 10−26 at the 90% confidence level. Our results exclude isolated neutron stars rotating faster than 5 ms with ellipticities greater than 5 × 10 − 8 d 100 pc within a distance d from Earth and r-mode amplitudes α ≥ 10 − 5 d 100 pc for neutron stars spinning faster than 150 Hz
Carbon isotope fractionation and depletion in TMC1
12C/13C isotopologue abundance anomalies have long been predicted for
gas-phase chemistry in molecules other than CO and have recently been observed
in the Taurus molecular cloud in several species hosting more than one carbon
atom, i.e. CCH, CCS, CCCS and HCN. Here we work to ascertain whether these
isotopologic anomalies actually result from the predicted depletion of the 13C+
ion in an oxygen-rich optically-shielded dense gas, or from some other more
particular mechanism or mechanisms. We observed 3mm emission from
carbon, sulfur and nitrogen-bearing isotopologues of HNC, CS and \HH CS at
three positions in Taurus(TMC1, L1527 and the ammonia peak) using the ARO 12m
telescope. We saw no evidence of 12C/13C anomalies in our observations.
Although the pool of C+ is likely to be depleted in 13C 13C is not depleted in
the general pool of carbon outside CO, which probably exists mostly in the form
of C^0. The observed isotopologic abundance anomalies are peculiar to those
species in which they are found.Comment: Accepted for publication in The Astrophysical Journal (mail journal
- …