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J.A.?Swansson K.G.H.?BaldwinEmail author M.D.?Hoogerland A.G.?Truscott S.J.?Buckman 《Applied physics. B, Lasers and optics》2004,79(4):485-489
We have developed a novel, high flux source of metastable rare gas atoms (helium, neon and argon) that uses liquid helium cooling to reduce the initial atomic velocity. Fluxes exceeding 1014 atoms/ster/s with He and Ne were obtained. With average velocities of 600 m/s for He and 300 m/s for Ne and Ar, this source will enable simpler, more compact beam lines for loading magneto-optical traps. PACS 34.80.Dp; 39.10.+j; 39.25.+k 相似文献
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A comprehensive DTA study is reported of ten polyhydroxy-phenols and eight naphthols and of the correspondingp-phenylazo benzoylchloride,p-nitrobenzoylchloride and 3,5-dinitrobenzoylchloride derivatives, prepared in situ by heating intimate mixtures of phenol and acid chloride in a conventional DTA system. The thermal analysis data and, in particular, the derivative formation temperatures, are interpreted in terms of the inductive, mesomeric and steric effects associated with the phenol and acid chloride and the extent of inter- and intramolecular hydrogen-bonding existing in these systems. The DTA data collectively, provide a comprehensive data base for the identification and characterisation of these phenols via DTA.
Zusammenfassung Dies ist eine umfassende DTA-Untersuchung von zehn Polyhydroxyphenolen und acht Naphtholen sowie der entsprechendenp-Phenylazobenzoylchlorid-,p-Nitrobenzoylchlorid- und 3,5-Dinitrobenzoylchlorid-Derivate, die durch Erhitzen inniger Gemische des jeweiligen Phenoles und Säurechlorides in situ in einem herkömmlichen DTA-Gerät hergestellt wurden. Die bei der Thermoanalyse erhaltenen Angaben, insbesondere die Bildungstemperatur der Derivate wurde bezüglich des induktiven, mesomeren und sterischen Effektes bei Phenol und Säurechlorid sowie der Stärke der in diesem System existierenden inter- und intramolekularen Wasserstoffbrückenbindungen interpretiert. Die Gesamtheit der DTA-Daten bietet eine umfassende Datensammlung für Identifizierung und Charakterisierung dieser Phenole mittels DTA.相似文献
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Jelisavcic M Panajotovic R Kitajima M Hoshino M Tanaka H Buckman SJ 《The Journal of chemical physics》2004,121(11):5272-5280
We report experimental results for electron scattering from perfluorocyclobutane, c-C(4)F(8), obtained from measurements in our two laboratories. A set of differential, integral, and momentum transfer cross sections is provided for elastic scattering for incident electron energies from 1.5 to 100 eV. Inelastic scattering (vibrational excitation) cross sections have been measured for incident electron energies of 1.5, 2, 5, 6, and 7 eV. In order to investigate the role of intermediate negative ions (resonances) in the scattering process we have also measured an excitation function for elastic scattering and vibrational excitation of the ground electronic state of C(4)F(8) for incident energies between 0.6 and 20 eV. These results are compared with the limited amount of data available in the literature for scattering from this molecule. 相似文献
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AW Hilkert CB Douthitt HJ Schlüter WA Brand 《Rapid communications in mass spectrometry : RCM》1999,13(13):1226-1230
Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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R.G. Dall M.D. Hoogerland D. Tierney K.G.H. Baldwin S.J. Buckman 《Applied physics. B, Lasers and optics》2002,74(1):11-18
We present a novel design for a single-mode, hollow optical fibre, which is suitable for use as a waveguide for atomic de
Broglie waves. The design, development and characterisation of such a fibre are discussed, as well as an optimised method
for coupling light into the fibre.
Received: 22 May 2001 / Revised version: 5 September 2001 / Published online: 29 November 2001 相似文献
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Buckman BO Ghannam A Angela L Liang M Mohan R Ng HP 《Combinatorial chemistry & high throughput screening》2002,5(3):249-251
An automated, parallel, solid-phase synthesis and screening strategy using commercially available aryl acetic acids as starting materials has discovered novel, non-peptide CCR1 antagonists (K(i) < 100 nM). 相似文献