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101.
102.
P. Peuser G. Herrmann H. Rimke P. Sattelberger N. Trautmann W. Ruster F. Ames J. Bonn H. -J. Kluge U. Krönert E. -W. Otten 《Applied physics. B, Lasers and optics》1985,38(4):249-253
Laser photoionization has been used to detect trace amounts of plutonium. A high sensitivity and selectivity has been achieved by applying three-step excitation and ionization of the plutonium atoms with high pulse-repetition rates and additional mass determination by time-of-flight measurements. A laser system was developed which consists of a copper vapor laser pumping three dye lasers simultaneously. Samples containing between 1010 and 1012 atoms of239Pu on Re filaments were measured yielding strong resonance signals with maximum ion count rates of several kHz at a vanishingly low background. A detection efficiency of 10–7 was determined allowing the detection of about 108 plutonium atoms in a sample.This work comprises part of the doctoral dissertation of W. Ruster, to be submitted to Johannes-Gutenberg-Universität, Mainz 相似文献
103.
Y. C. Jean T. C. Sandreczki D. P. Ames 《Journal of Polymer Science.Polymer Physics》1986,24(6):1247-1258
Positronium annihilation spectroscopy (PAS) has been used to study the microstructural properties of amine-cured epoxy polymers. We have determined the free-volume “hole” sizes in these polymers by comparing the observed ortho-positronium lifetimes with the known lifetime–free volume correlation for low-molecular-weight systems. The free volumes for four epoxies with different crosslink densities are found to vary significantly over the temperature range between ?78° and 250°C. The free-volume holes for these polymers are found to range from 0.025 to 0.220 nm3. Two important transition temperatures were found: one corresponds to the glass transition temperature Tg determined by differential scanning calorimetry (DSC), and the other occurs about 80–130°C below Tg. The sub-Tg transition temperature is interpreted tentatively as being where hole size reaches dimensions adequate for positronium trapping or else the onset temperature for local mode or side-chain motions. These two transition temperatures plus two additional onset temperatures are found to be correlated with crosslink densities calculated from stoichiometry. 相似文献
104.
A. Breakstone R. Campanini H. B. Crawley G. M. Dallavalle M. M. Deninno K. Doroba D. Drijard F. Fabbri A. Firestone H. G. Fischer H. Frehse W. Geist G. Giacomelli R. Gokieli M. Gorbics P. Hanke M. Heiden W. Herr D. Isenhower E. E. Kluge J. W. Lamsa T. Lohse W. T. Meyer G. Mornacchi T. Nakada M. Panter A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling G. P. Siroli J. D. Skeens R. Sosnowski M. Szczekowski O. Ullaland D. Wegener R. Yeung Ames Collaboration Bologna Collaboration CERN Collaboration Dortmund Collaboration Heidelberg Collaboration Warsaw Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(3):522-522
Data are presented for the first time on inclusive Pomeron-Pomeron interactions which produce a central systemX (composed mainly of multimeson states) in proton-proton collisions at \(\sqrt s \) at the CERN ISR. The systemX has a Feynman-x distribution which is sharply peaked atx f=0, is inconsistent with any significant contributions from Reggeon exchange processes, and has an invariant mass dependence in good agreement with the predicted formM x ?2 . Kaon production is about 15% of pion production, nearly independent ofM x, while proton-antiproton production averages about 5% of pion production and increases withM x. The structure of the central systemX develops into a jetlike shape, asM x increases, as would be expected from a model of Pomeron fragmentation. The shape of thex f(π) distribution in the center of mass of theX system (although not proving existence) is consistent with asoft partonic substructure of the Pomeron. 相似文献
105.
Raman and resonance-Raman spectra of the I?3 ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν1) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar+ laser line. Bands centred at 153, 170, 264 and 304 cm?1 have been assigned as ν3, 2ν2, ν1+ν3 and 2ν3(Σ+) respectively. The remaining structure between the nν1 lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal. 相似文献
106.
K. Utescher Hunnius W. Hoffmann U. Springer H. Kappen D. J. Hissink K. Gedroiz A. Gehring O. Wehrmann A. Peggau H. Nicklas A. Hockl J. Hudig C. W. G. Hetterschyl J. v. Csiky J. W. Ames C. J. Schollenberger D. V. Moses J. H. Griffith M. Köhn P. Köttgen A. Rippell T. Baumaärtell H. Niklas W. Hirschbergen 《Analytical and bioanalytical chemistry》1930,80(11-12):459-476
107.
Jec-Kong Gone Ilhan Olmez M.R. Ames 《Journal of Radioanalytical and Nuclear Chemistry》2000,244(1):133-139
Size-segregated atmospheric particulate material was collected at a rural location in the Great Smokey Mountain National Park, Tennessee, and at an urban site in Pasadena, California. The elemental composition of this material was determined by Instrumental Neutron Activation Analysis. Elements identified as being of anthropogenic origin had mass median diameters of below one micron, while elements of crustal origin were generally found to have a mass median diameters well over one micron. Some of the Pasadena samples however had elevated concentrations of the typical crustal elements Al, Fe, La, and Ce in the finer size fractions, probably due to motor vehicle emissions. 相似文献
108.
S. Schwarz F. Ames G. Audi D. Beck G. Bollen J. Dilling F. Herfurth H.-J. Kluge A. Kellerbauer A. Kohl D. Lunney R.B. Moore H. Raimbault-Hartmann C. Scheidenberger G. Sikler J. Szerypo 《Hyperfine Interactions》2001,132(1-4):335-338
The recent implementation of gas-filled radiofrequency traps for efficient ion beam bunching extended the applicability of
the Penning trap mass spectrometer ISOLTRAP/CERN to non-surface ionizable species. In a first series of successful runs the
masses of 182–197Hg, 196,198Pb, 197Bi, 198Po and 203At have been determined with an accuracy of 1⋅10−7. In order to unambiguously determine the ground state mass the ground and isomeric states of 185,187,191,193,197Hg were separated applying a resolving power of up to 3.7⋅106. First experimental values for the isomeric excitation energy of 187,191Hg were obtained.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
109.
Bruce N. Ames Lois Swirsky Gold 《Angewandte Chemie (International ed. in English)》1990,29(11):1197-1208
The public has numerous misconceptions about the relationship between environmental pollution and human cancer. Underlying these misconceptions is an erroneous belief that nature is benign. In this article we highlight eight of these misconceptions and describe the scientific information that undermines each one. 相似文献
110.
F. Ames A. Becker H. -J. Kluge H. Rimke W. Ruster N. Trautmann 《Fresenius' Journal of Analytical Chemistry》1988,331(2):133-135
Summary A laser ion source has been set up which is based on resonant stepwise excitation and ionization of atomic vapor confined in an ionization chamber. Using a pulsed copper vapor/dye laser system with a high repetition rate (6.5 kHz) one expects high efficiency and high selectivity for this new type of ion source. First test experiments with lead are reported.
Eine Laserionenquelle zur Spurenanalyse相似文献