Search results for "ZA"
showing 10 items of 45515 documents
Ab initio determination of the ionization potentials of water clusters (H2O)n (n = 2-6).
2012
High-level quantum-chemical ab initio coupled-cluster and multiconfigurational perturbation methods have been used to compute the vertical and adiabatic ionization potentials of several water clusters: dimer, trimer, tetramer, pentamer, hexamer book, hexamer ring, hexamer cage, and hexamer prism. The present results establish reference values at a level not reported before for these systems, calibrating different computational strategies and helping to discard less reliable theoretical and experimental data. The systematic study with the increasing size of the water cluster allows obtaining some clues on the structure and reductive properties of liquid water.
Time-resolved photoisomerization of 1,1′-di-tert-butylstilbene and 1,1′-dicyanostilbene
2016
Abstract Photoisomerization of 1,1′-di-tert-butylstilbene ( 3 ) and 1,1′-dicyanostilbene ( 4 ) is monitored with stationary and broadband transient absorption spectroscopy. The electron affinity of the substituents correlates with the shift of the absorption band. The weak extinction of 3 complicates data interpretation, but comparison with earlier measured 1,1′-dimethylstilbene ( 1 ) and 1,1′-diethylstilbene ( 2 ) helps to assign transient spectra and relaxation paths. For 3 a long-lived perpendicular state P is observed with lifetime τ P = 134 ps in acetonitrile. For 4 τ P = 2.1 ps in acetonitrile and 27 ps in n-hexane, the difference indicating a substantial dipole moment (∼3D) of the …
Quantum stereodynamics of the 18O+16O16O→16O18O+16O exchange reaction at low collision energy
2017
Abstract We present a quantum study of stereodynamics of the 18 O + 16 O 16 O ( v = 0 , j = 1 ) → 16 O 18 O ( v ′ = 0 , j ′ ) + 16 O exchange reaction at a collision energy E coll = 0.01 eV . Polarization moments of the reactants have been computed and stereodynamical portraits have been generated. The results show that the reactant preferred relative orientations are strongly dependent on the scattering angle and on the product rotational states.
Direct mass measurements and ionization potential measurements of the actinides
2019
Abstract The precise determination of atomic and nuclear properties such as masses, differential charge radii, nuclear spins, electromagnetic moments and the ionization potential of the actinides has been extended to the late actinides in recent years. In particular, laser spectroscopy and mass spectrometry have reached the region of heavy actinides that can only be produced only at accelerator facilities. The new results provide deeper insight into the impact of relativistic effects on the atomic structure and the evolution of nuclear shell effects around the deformed neutron shell closure at N = 152. All these experimental activities have also opened the door to extend such measurements t…
Model building on the non-factorisable type IIA T6/(Z4×ΩR) orientifold
2016
We construct global semi-realistic supersymmetric models with intersecting D6-branes on the non-factorisable orientifold . The non-factorisable structure gives rise to differences compared to the factorisable case: additional conditions for the three-cycles to be Lagrangian and extra constraints on the wrapping numbers for building fractional cycles.
Measurement of the laser resonance ionization efficiency for lutetium
2019
Abstract The development of a highly efficient resonance ionization scheme for lutetium is presented. A laser ion source, based on the all-solid-state Titanium:sapphire laser system, was used at the 30 keV RISIKO off-line mass separator to characterize different possible optical excitation schemes in respect to their ionization efficiency. The developed laser resonance ionization scheme can be directly applied to the use at radioactive ion beam facilities, e. g. at the CERN-MEDICIS facility, for large-scale production of medical radioisotopes.
Photoionization cross sections of the 5S1/2 and 5P3/2 states of Rb in simultaneous magneto-optical trapping of Rb and Hg
2018
We report the measurement of the photoionization cross sections of the $5{S}_{1/2}$ and $5{P}_{3/2}$ states of $^{87}\mathrm{Rb}$ in a two-species Hg and Rb magneto-optical trap (MOT) by the cooling laser for Hg. The photoionization cross sections of Rb in the $5{S}_{1/2}$ and $5{P}_{3/2}$ states at 253.7 nm are determined to be ${1}_{\ensuremath{-}1}^{+4.3}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\phantom{\rule{0.28em}{0ex}}{\text{cm}}^{2}$ and $4.63(30)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}\phantom{\rule{0.28em}{0ex}}{\text{cm}}^{2}$, respectively. To measure the $5{S}_{1/2}$ and $5{P}_{3/2}$ state fractions in the MOT we detected the photoionization rat…
Polarization-driven spin precession of mesospheric sodium atoms: publisher's note.
2018
This publisher's note corrects an error in the author listing of Opt. Lett.43, 5825 (2018)OPLEDP0146-959210.1364/OL.43.005825.
Sensitive Assays by Nucleophile-Induced Rearrangement of Photoactivated Diarylethenes.
2018
Upon light-induced isomerization, diarylethenes (DAEs) equipped with reactive aldehyde moieties rearrange selectively in the presence of amines, accompanied by decoloration. In a comprehensive study, the probe structure was optimized with regard to its inherent reactivity in the nucleophile-triggered rearrangement reaction. Detailed structure−reactivity relationships could be derived, in particular with regard to the type of integrated (het)aryl moieties as well as the location of the formyl residue, and the probes’ intrinsic reactivity with primary and secondary amines was optimized. Utilizing an ancillary base, the initially formed rearrangement product can engage in a subsequent catalyti…
The Taming of Redox‐Labile Phosphidotitanocene Cations
2019
International audience; Tame d0 phosphidotitanocene cations stabilized with a pendant tertiary phosphane arm are reported. These compounds were obtained by one-electron oxidation of d1 precursors with [Cp2Fe][BPh4]. The electronic structure of these compounds was studied experimentally (EPR, UV/Vis, and NMR spectroscopy, X-ray diffraction analysis) and through DFT calculations. The theoretical analysis of the bonding situation by using the electron localization function (ELF) shows the presence of π-interactions between the phosphido ligand and Ti in the d0 complexes, whereas dπ–pπ repulsion prevents such interactions in the d1 complexes. In addition, CH–π interactions were observed in seve…