Search results for "ddc:"
showing 10 items of 3080 documents
Low temperature X-ray absorption spectroscopy study of $CuMoO_{4}$ and $CuMo_{0.90}W_{0.10}O_4$ using reverse Monte-Carlo method
2020
Radiation physics and chemistry 175, 108411 (2020). doi:10.1016/j.radphyschem.2019.108411
Cooperative phenomena and light-induced bistability in iron(II) spin-crossover compounds
1999
In iron(II) spin-crossover compounds, the transition from the 1A1 low-spin state at low temperatures to the 5T2 high-spin state at elevated temperatures is accompanied by a large increase in metal-ligand bond lengths. The resulting elastic interactions may be pictured as an internal pressure which is proportional to the concentration of the low-spin species. Because pressure stabilises the low-spin state relative to the high-spin state this results in a positive feedback. Thermal transition curves in neat iron(II) spin-crossover compounds are thus invariable much steeper than in diluted mixed crystals, and the high-spin→low-spin relaxation following the light-induced population of the high-…
A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.
2014
Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, ex…
Moral Attitudes Toward Pharmacological Cognitive Enhancement (PCE): Differences and Similarities Among Germans With and Without PCE Experience
2018
Pharmacological cognitive enhancement (PCE), the use of illicit and/or prescription drugs to increase cognitive performance, has spurred controversial discussion in bioethics. In a semi-structured interview study with 60 German university students and employees, differences and similarities in moral attitudes toward PCE among 30 experienced participants (EPs) vs. 30 inexperienced participants (IPs) were investigated. Substances EPs used most often are methylphenidate, amphetamines, tetrahydrocannabinol and modafinil. Both EPs and IPs addressed topics such as autonomous decision making or issues related to fairness such as equality in test evaluation and distortion of competition. While most…
Symmetry-species conversion in CD3systems
1993
The rates for symmetry-species conversion of CD3 groups are calculated using a model in which the interaction between the quadrupolar moment of the deuterons with electric-field gradient at the site of the nucleus causes symmetry-changing transitions. Just the same phonons are considered for energy conservation as are used to describe the temperature dependence of inelastic neutron scattering experiments. For the conversion rate, a similar temperature dependence is found as has already been obtained for CH3. For temperatures around the tunnelling energy, a behaviour is predicted for CD3 that is different from the behaviour in protonated systems according to all theories known to the authors…
NMR enantiodifferentiation of triphenylphosphonium salts by chiral hexacoordinated phosphate anions
2003
BINPHAT anion—rather than TRISPHAT—is an efficient NMR chiral shift reagent for triphenylphosphonium salts containing stereogenic centers on the aliphatic side-chain. BINPHAT—rather than TRISPHAT—anion is an efficient NMR (1H and 31P) chiral shift reagent for chiral triphenylphosphonium salts.
A theoretical study of the lowest electronic states of azobenzene: the role of torsion coordinate in the cis-trans photoisomerization
2003
In the present paper we report the results of a multiconigurational computational study on potential- energy curves of azobenzene along the NN twisting to clarify the role of this coordinate in the decay of the S2(pp*) and S1(np*) states. We have found that there is a singlet state, S3 at the trans geometry, on the basis of the doubly excited coniguration n 2 p* 2 , that has a deep minimum at about 90 of twisting, where it is the lowest excited singlet state. The existence of this state provides an explanation for the short lifetime of S2(pp*) and for the wavelength-dependence of azobenzene photochem- istry. We have characterized the S1(np*) state by calcu- lating its vibrational frequencie…
Optical properties of phosphorous-related point defects in silica fiber preforms
2009
Physical review / B 80, 205208 (2009). doi:10.1103/PhysRevB.80.205208
Measurement of the atmospheric muon flux with a 4 GeV threshold in the ANTARES neutrino telescope
2010
A new method for the measurement of the muon flux in the deep-sea ANTARES neutrino telescope and its dependence on the depth is presented. The method is based on the observation of coincidence signals in adjacent storeys of the detector. This yields an energy threshold of about 4 GeV. The main sources of optical background are the decay of 40K and the bioluminescence in the sea water. The 40K background is used to calibrate the efficiency of the photo-multiplier tubes.
Roadmap on STIRAP applications
2019
STIRAP (stimulated Raman adiabatic passage) is a powerful laser-based method, usually involving two photons, for efficient and selective transfer of populations between quantum states. A particularly interesting feature is the fact that the coupling between the initial and the final quantum states is via an intermediate state, even though the lifetime of the latter can be much shorter than the interaction time with the laser radiation. Nevertheless, spontaneous emission from the intermediate state is prevented by quantum interference. Maintaining the coherence between the initial and final state throughout the transfer process is crucial. STIRAP was initially developed with applications in …