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981.
Adamová D Agakichiev G Antończyk D Appelshäuser H Belaga V Bielcíková J Braun-Munzinger P Busch O Cherlin A Damjanovic S Dietel T Dietrich L Drees A Esumi SI Filimonov K Fomenko K Fraenkel Z Garabatos C Glässel P Hering G Holeczek J Krobath G Kushpil V Ludolphs W Maas A Marín A Milosević J Miśkowiec D Ortega R Panebrattsev Y Petchenova O Petrácek V Radomski S Rak J Ravinovich I Rehak P Sako H Schmitz W Schukraft J Sedykh S Shimansky S Stachel J Sumbera M Tilsner H Tserruya I Tsiledakis G 《Physical review letters》2006,96(15):152301
We report on results of a measurement of meson production in central Pb-Au collisions at E(lab) = 158A GeV. For the first time in the history of high energy heavy-ion collisions, phi mesons were reconstructed both in the K+K- and the dilepton decay channels in the same experiment. This measurement yields rapidity densities near midrapidity, from the two decay channels, of 2.05 +/- 0.14(stat) +/- 0.25(syst) and 2.04 +/- 0.49(stat) +/- 0.32(syst), respectively. The shape of the measured transverse momentum spectrum is also in close agreement in both decay channels. The data rule out a possible enhancement of the phi yield in the leptonic over the hadronic decay channel of a factor 1.6 or larger at the 95% C.L. This rules out the discrepancy reported in the literature between measurements of the hadronic and dimuon decay channels by two different experiments. 相似文献
982.
Kruk J Myśliwa-Kurdziel B Jemioła-Rzeminiska M Strzałka K 《Photochemistry and photobiology》2006,82(5):1309-1314
We have found that for biological prenyllipids, such as plastoquinol-9, alpha-tocopherol quinol, and alpha-tocopherol, the shortest fluorescence lifetimes were found in aprotic solvents (hexane, ethyl acetate) whereas the longest lifetimes were those of ubiquinonol-10 in these solvents. For all the investigated prenyllipids, fluorescence lifetime in alcohols increased along with an increase in solvent viscosity. In a concentrated hexane solution, the lifetimes of prenylquinols considerably decreased. This contrasts with methanol solutions, which is probably due to the self-association of these compounds in aprotic solvents. We have also found a correlation of the Stokes shift of prenyllipids fluorescence with the orientation polarizability of the solvents. Based on data obtained in organic solvents, measurements of the fluorescence lifetimes of prenyllipids in liposomes allowed an estimation of the relative distance of their fluorescent rings from the liposome membrane surface, and was found to be the shortest for alpha-tocopherol quinol in egg yolk phosphatidylcholine liposomes, and increased in the following order: alpha-tocopherol in dipalmitoyl phosphatidylcholine liposomes < alpha-tocopherol < plastoquinol-9 < ubiquinol-10 in egg-yolk phosphatidylcholine liposomes. 相似文献
983.
Szymczak JJ Urban J Roszak S Leszczynski J 《The journal of physical chemistry. A》2006,110(48):13099-13105
The presence of solvent molecules, even inert, may significantly influence processes taking place in the gas phase. The reason for the solvent activity may be found in studies of complexes originating from microsolvation. The structure, thermodynamics, and vibrational properties of NH(4)(+)Ar(n) (n = 0-5) and NH(3)Ar(n) (n = 0-4) complexes are presented in this work with the aim to elucidate the effect of microsolvation on protonation/deprotonation processes. The relation between the nature of interactions in cationic and neutral clusters and the proton affinity is studied as a function of the number of ligands in complexes. 相似文献
984.
Adrich P Klimkiewicz A Fallot M Boretzky K Aumann T Cortina-Gil D Pramanik UD Elze TW Emling H Geissel H Hellström M Jones KL Kratz JV Kulessa R Leifels Y Nociforo C Palit R Simon H Surówka G Sümmerer K Waluś W;LANDS-FRS Collaboration 《Physical review letters》2005,95(13):132501
The dipole strength distribution above the one-neutron separation energy was measured in the unstable 130Sn and the double-magic 132Sn isotopes. The results were deduced from Coulomb dissociation of secondary Sn beams with energies around 500 MeV/nucleon, produced by in-flight fission of a primary 238U beam. In addition to the giant dipole resonance, a resonancelike structure ("pygmy resonance") is observed at a lower excitation energy around 10 MeV exhausting a few percent of the isovector E1 energy-weighted sum rule. The results are discussed in the context of a predicted new dipole mode of excess neutrons oscillating out of phase with the core nucleons. 相似文献
985.
986.
Dr. Arkadiusz Listkowski Dr. Natalia Masiera Michał Kijak Dr. Roman Luboradzki Dr. Barbara Leśniewska Prof. Jacek Waluk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(20):6324-6333
Porphycene, a porphyrin isomer, is an efficient fluorophore. However, four-fold meso substitution with alkyl groups decreases the fluorescence quantum yield by orders of magnitude. For aryl substituents, this effect is small. To explain this difference, we have synthesized and studied a mixed aryl-alkyl-substituted compound, 9,20-diphenyl-10,19-dimethylporphycene, as well as the 9,20-diphenyl and 9,20-dimethyl derivatives. Analysis of the structural, spectroscopic, and photophysical data of the six porphycenes, combined with quantum chemical calculations, shows a clear correlation between the strength of the intramolecular NH⋅⋅⋅N hydrogen bonds and the efficiency of the radiationless depopulation of the lowest-excited singlet state. This result led us to propose a model in which the delocalization of the inner protons in the cavity of the macrocycle is responsible for the nonradiative deactivation channel. The applicability of the model is confirmed by the literature data for other alkyl- or aryl-substituted porphycenes. The finding of a correlation between structural and emissive characteristics enables a rational design of porphycenes with desired photophysical properties. 相似文献
987.
The influence of dilute concentrations (<10 at.%) of Pt-group metals (Re, Ru, Os, Ir, Pd and Pt) on the thermal-stability of melt-spun (Fe or Ni) Si10B12-based amorphous alloys has been investigated by differential scanning calorimetry. The stability of the Fe-based alloys, with the exception of those containing Pd or Pt, can be related to both the electronic and atomic-size differences between solvent and solute metal species, as we observed previously for other solutes from groups IVa–VIa. Addition of Ru, Pd or Pt to glassy NiSi10B12 has little effect on the stability, and no correlation with atomic size or electron concentration could be established. 相似文献
988.
Jaroslaw A. Wiśniewski 《Mathematische Zeitschrift》1993,214(1):261-271
989.
990.
R. Lisiecki W. Ryba-Romanowski C. Koepke K. Wiśniewski D. Pivatkowski 《Applied physics. B, Lasers and optics》2008,91(1):65-70
Excited state absorption (ESA) of Tm3+ ions in YVO4 crystal was measured using a pump and probe technique. The measurements have been performed in the wide spectral range in
both the near infrared and visible region between 6000 cm-1 (NIR) and 24000 cm-1 (VIS). ESA absorption cross section spectra have been calculated for transitions from the 3
F
4 and 3
H
4 states of Tm3+ and compared to those evaluated experimentally. The excited state absorption in YVO4:Tm3+ should not influence the laser operation related to the 3F4→3H6 transition around 1900 nm, but it will be a significant loss factor for a potential laser action associated with the 3H4→3F4 transition around 1.48 μm.
PACS 42.55.Xi; 42.62.Fi 相似文献