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81.
M. Karny L. Batist B. A. Brown D. Cano-Ott R. Collatz A. Gadea R. Grzywacz A. Guglielmetti M. Hellstrm Z. Hu Z. Janas R. Kirchner F. Moroz A. Piechaczek A. P
ochocki E. Roeckl B. Rubio K. Rykaczewski M. Shibata J. Szerypo J. L. Tain V. Wittmann A. Whr 《Nuclear Physics A》2001,690(4):45
The Gamow–Teller β decays of the neutron-deficient indium isotopes 104–107In have been investigated by using total absorption γ-ray spectrometry on mass-separated sources. The experimental Gamow–Teller strength, deduced as a function of the excitation energy in the daughter nuclei 104–107Cd, is compared to shell-model predictions. 相似文献
82.
83.
C. Kirchner V. Schwegler F. Eberhard M. Kamp K. J. Ebeling
P. Prystawko
M. Leszczynski I. Grzegory S. Porowski 《Progress in Crystal Growth and Characterization of Materials》2000,41(1-4):57-83Epitaxial growth on GaN bulk single crystal substrates sets new standards in GaN material quality. The outstanding properties provide insights into fundamental material parameters (e.g. lattice constants, exciton binding energies, etc.) with a precision not obtainable from heteroepitaxial growth on sapphire or SiC. With metalorganic vapor phase epitaxy (MOVPE) we realized unstrained GaN layers with dislocation densities about six orders of magnitude lower than in heteroepitaxy. By the use of dry etching techniques for surface preparation, an important improvement of crystal quality is achieved. Those layers reveal an exceptional optical quality as determined by a reduction of the low-temperature photoluminescence (PL) linewidth from 5 meV to 0.1 meV and a reduced X-ray diffraction (XRD) rocking curve width from 400 to 20 arcsec. As a consequence of the narrow PL linewidths, new features as, e. g. a fivefold fine structure of the donor-bound exciton line at 3.471 eV was detected. Additionally, all three free excitons as well as their excited states are visible in PL at 2 K.
Dry etching techniques for surface preparation allow morphologies of the layers suitable for device applications. We report on InGaN/GaN multi-quantum-well (MQW)_ structures as well as GaN pn- and InGaN/GaN double heterostructure light emitting diodes (LEDs) on GaN bulk single crystal substrates. Those LEDs are twice as bright as their counterparts grown on sapphire. In addition they reveal an improved high power characteristics, which is attributed to an enhanced crystal quality and an increased p-doping. 相似文献
84.
85.
Dr. Eva Kirchner Dr. David Bialas Marius Wehner Dr. David Schmidt Prof. Frank Würthner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(48):11285-11293
A series of three bis(merocyanine) dyes comprising chromophores of different conjugation lengths has been synthesized and the intramolecular aggregation process was investigated by UV/Vis absorption spectroscopy. The spectral changes observed upon variation of the solvent polarity reveal a folding process resulting in a cofacial π-stack of two chromophores with a decrease of the aggregation tendency with increasing chromophore length and solvent polarity. Solvent-dependent UV/Vis studies of the monomeric reference dyes show a significant increase of the polyene-like character for dyes with longer polymethine chains in nonpolar solvents, which is reversed upon aggregation due to the polarizability effect of the adjacent chromophore within the dye stack. The pronounced hypsochromic shift of the absorption band observed upon aggregation indicates strong coupling of the dyes’ transition dipole moments, which was confirmed by quantum-chemical analysis. 相似文献
86.
87.
L. Batist A. Bykov F. Moroz V. Wittmann G. D. Alkhazov H. Keller R. Kirchner O. Klepper E. Roeckl M. Huýse P. Van Duppen G. Reusen A. Płochocki M. Pfützner K. Rykaczewski J. Szerypo J. Żylicz B. A. Brown 《Zeitschrift für Physik A Hadrons and Nuclei》1995,351(2):149-153
The EC/β+-decay of the odd-odd nucleus100Ag was studied by means of total absorptionγ-ray spectrometry. Most of the Gamow-Teller strength was found to be concentrated at an excitation energy of 5.6 MeV in100Pd, the FWHM of this resonance being 1.5 MeV. The measured strength distribution which is interpreted within the BCS approximation as being due to the dominant population of four-quasiparticle excitations, resembles the distribution predicted by an advanced shell-model calculation for the98Ag →98Cd decay. 相似文献
88.
Karl Kirchner Rudolf Jedlicka Roland Schmid 《Monatshefte für Chemie / Chemical Monthly》1992,123(3):203-209
Summary Half-wave potentials,E
1/2, of Fe(ligand)
6
3+/2+
, as ClO
4
–
salt, [ligand=N,N-dimethylformamide (dmf), acetamide (aa), N,N-dimethylacetamide (dma), trimethylphosphate (tmp), dimethylsulfoxide (dmso), and acetonitrile (MeCN) are given. A linear correlation betweenE
1/2 and Gutmann's donor numbers of the ligands, a parameter which expresses quantitatively the Lewis donor properties towards hard acceptors, was found. Ligand replacement on Fe(ligand)
6
3+
in acetonitrile-d
3 was studied by means of1H-NMR spectroscopy at 20°C. An average number of ligands coordinated to Fe3+,n
coord, is given.n
coord increases with the ligand's donor strength; i.e.tmp<dmf<dmso.Dedicated to Prof. Dr. mult. Viktor Gutmann on the occasion of his 70th birthday 相似文献
89.
Elaine Smith Steven D. Gray Heather Dove Lester Kirchner Heidi Heras 《Journal of voice》1997,11(1):81-87
This study compared the frequency and effects of voice symptomsin teachers to a group of individuals employed in other occupations. Teachers were more likely to report having a voice problem (15 vs. 6%), having 10 specific voice symptoms, and having 5 symptoms of physical discomfort. They averaged almost 2 symptoms compared with none for nonteachers. Likewise, teachers were more likely to perceive that a voice problem would adversely affect their future career options, had done so in the past, and was limiting their current job performance. Over 20% of teachers but none of the nonteachers had missed any days of work due to a voice problem. These findings suggest that teaching is a high-risk occupation for voice disorders and that this health problem may have significant work-related and economic effects. 相似文献
90.