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Poutsma JC Midey AJ Thompson TH Viggiano AA 《The journal of physical chemistry. A》2006,110(39):11315-11319
The absolute rate coefficients and product ion branching percentages at 298 K for the reactions of several POxCly- species with atomic nitrogen (N (4S(3/2))) and atomic oxygen (O (3P)) have been determined in a selected-ion flow tube (SIFT) instrument. POxCly- ions are generated by electron impact on POCl3 in a high-pressure source. O atoms are generated by quantitative titration of N atoms with NO, where N atoms are produced by microwave discharge on N2. The experimental procedure allows for the determination of rate coefficients for the reaction of the reactant ion with N (4S(3/2)) and O (3P) as well as with N2 and NO. None of the ions react with N2 or NO, giving an upper limit to the rate coefficient of <5 x 10(-12) cm3 molecules(-1) s(-1). POCl3- and POCl2- do not react with N atoms, giving an upper limit to the rate coefficient of <1 x 10(-11) cm3 molecules(-1) s(-1). The major product ion for POCl3- and POCl2- reacting with O involves loss of Cl from the reactant ion, accounting for >85% of the products. PO2- is a minor product (相似文献
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CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Anthony Midey Itzhak Dotan J.V. Seeley A.A. Viggiano 《International journal of mass spectrometry》2009,280(1-3):6
The rate constants and product ion branching ratios were measured for the reactions of various small negative ions with O2(X 3Σg−) and O2(a 1Δg) in a selected ion flow tube (SIFT). Only NH2− and CH3O− were found to react with O2(X) and both reactions were slow. CH3O− reacted by hydride transfer, both with and without electron detachment. NH2− formed both OH−, as observed previously, and O2−, the latter via endothermic charge transfer. A temperature study revealed a negative temperature dependence for the former channel and Arrhenius behavior for the endothermic channel, resulting in an overall rate constant with a minimum at 500 K. SF6−, SF4−, SO3− and CO3− were found to react with O2(a 1Δg) with rate constants less than 10−11 cm3 s−1. NH2− reacted rapidly with O2(a 1Δg) by charge transfer. The reactions of HO2− and SO2− proceeded moderately with competition between Penning detachment and charge transfer. SO2− produced a SO4− cluster product in 2% of reactions and HO2− produced O3− in 13% of the reactions. CH3O− proceeded essentially at the collision rate by hydride transfer, again both with and without electron detachment. These results show that charge transfer to O2(a 1Δg) occurs readily if the there are no restrictions on the ion beyond the reaction thermodynamics. The SO2− and HO2− reactions with O2(a) are the only known reactions involving Penning detachment besides the reaction with O2− studied previously [R.S. Berry, Phys. Chem. Chem. Phys., 7 (2005) 289–290]. 相似文献
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Rate constants have been measured from 300 to 1400 K in a selected ion flow tube (SIFT) and a high temperature flowing afterglow for the reactions of N+, N2+ and N3+ with NO. In all of the systems, the rate constants are substantially less than the collision rate constant. Comparing the high temperature results to kinetics studies as a function of translational energy show that all types of energy (translational, rotational, and vibrational) affect the reactivity approximately equally for all three ions. Branching ratios have also been measured at 300 and 500 K in a SIFT for the N+ and N3+ reactions. An increase in the N2+ product at the expense of NO+ nondissociative charge transfer product occurs at 500 K with N+. The branching ratios for the reaction of N3+ with NO have also been measured in the SIFT, showing that only nondissociative charge transfer giving NO+ occurs up to 500 K. The current results are discussed in the context of the many previous studies of these ions in the literature. 相似文献
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