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91.
Richard Ley D. Hagena D. Weil G. Werth W. Arnold H. Schneider 《Hyperfine Interactions》1994,89(1):327-341
Electric dipole transitions in the microwave range have been induced between the fine-structure levels of positronium in the excited staten=2. As an indication of the transitions, we used the increase in Lyman- radiation when the metastable 23S1-level is depopulated. The results for the transitions 23S123P0,1,2 are
0=18499.65±1.20±4.00 MHz,
1=13012.42 ±0.65±1.54 MHz and
2=8624.38±0.54±1.40 MHz. The first error is statistical and the second systematic. The precision of the present measurement has improved by a factor of 3, compared to previous data. Recent bound state QED-calculations have been extended to the orderR
t8
4ln
–1. The not yet completely calculated orderR
t8
4 is estimated to contribute less than 1 MHz. Our experimental results are in good agreement with theory. By applying a weak magnetic field, we were able to observe the transition 23S121P1 which is strictly forbidden byC-invariance in zero field. Our result, corrected for Zeeman- and motional Starkeffect, is
3=11180.0±5.0±4.0 MHz. An upper limit for theC-violating matrix element of
MHz could be deduced. Our experiment used moderated slow positrons from the bremsstrahlung and pair production of a pulsed electron linear accelerator (TEPOS facility at the university of Giessen). 相似文献
92.
R. Kadono J. H. Brewer K. Chow S. R. Kreitzman Ch. Niedermayer T. M. Riseman J. W. Schneider T. Yamazaki 《Hyperfine Interactions》1994,85(1):259-264
The electric quadrupole interaction of55Mn nuclei was studied in the weakly ferromagnetic system MnSi using muon level-crossing resonance (LCR) technique. The temperature dependence of the electric field gradient (EFG) shows a critical behavior near the ferromagnetic transition temperature, indicating that the EFG due to the conduction electron is strongly correlated with the magnetic susceptibility in the itinerant electron magnetism. The temperature dependence of EFG is in reasonable agreement with the self-consistent renormalization theory developed by Moriya and coworkers.We gratefully acknowledge helpful discussion with Dr. N. Nishida. We also wish to thank Keith Hoyle and Curtis Ballard for technical support. 相似文献
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A gas-chromatographic analyzer allowing the selective detection of individual oxygenates in complex organic mixtures, such as gasolines, is described. The analyzer is based on the oxygen-specific response flame ionization detection (O-FID) method. The system operates with capillary columns and includes a cracking reactor to convert any oxygenate to carbon monoxide and a special FID equipped with a microreactor for the catalytic hydro-genation of CO and detection as methane. Hydrocarbons give no signal. The selectivity of the method is better than 1:107 and the linear range approaches 105. The analysis of modern fuels containing oxygenated additives, to improve octane ratings, may greatly benefit from the proposed analytical method. 相似文献