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51.
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53.
Wang M Quist HE Hansen BJ Peng Y Zhang Z Hawkins AR Rockwood AL Austin DE Lee ML 《Journal of the American Society for Mass Spectrometry》2011,22(2):369-378
The halo ion trap (IT) was modified to allow for axial ion ejection through slits machined in the ceramic electrode plates
rather than ejecting ions radially to a center hole in the plates. This was done to preserve a more uniform electric field
for ion analysis. An in-depth evaluation of the higher-order electric field components in the trap was also performed to improve
resolution. The linear, cubic and quintic (5th order) electric field components for each electrode ring inside the IT were
calculated using SIMION (SIMION version 8, Scientific Instrument Services, Ringoes, NJ, USA) simulations. The preferred electric
fields with higher-order components were implemented experimentally by first calculating the potential on each electrode ring
of the halo IT and then soldering appropriate capacitors between rings without changing the original trapping plate design.
The performance of the halo IT was evaluated for 1% to 7% cubic electric field (A
4/A
2) component. A best resolution of 280 (m/Δm) for the 51-Da fragment ion of benzene was observed with 5% cubic electric field component. Confirming results were obtained
using toluene, dichloromethane, and heptane as test analytes. 相似文献
54.
There are many reports1 of the pyrolysis of fluorinated organic compounds, including the defluorination of cyclic fluorocarbons over iron to give aromatic compounds. Extending this technique we have investigated the flow pyrolysis of some readily accessible unsaturated fluorocarbons, such as I, II, and III, and found these to be synthetically useful routes to fluorinated dienes, cyclobutenes, and furans. Pyrolyses were carried out using a nitrogen flow over platinum, iron or caesium fluoride heated at 430–700°. The various products can all be rationalized in terms of intermediate allylic radicals, and the solid substrate influences which allylic radicals are formed.We are also investigating the chemistry of those now accessible compounds, such as IV, V, and VI, and some of the preliminary results are described. For example the fluoride ion induced dimerisation of IV gave two major products VII and VIII via a particular interesting mechanism. 相似文献
55.
has been studied by using a complete active space MCSCF wave function generated by distributing eight electrons among eight orbitals. 相似文献