Ion-molecule reactions, with

The composition of these beams was estimated on the basis of the lower reactivity of the metastable atom as compared to that of the ground-state atoms in ion-molecule reactions with H2+, for example.332... 

The domain of ion/molecule reactions with acetone and ketones in general is very large and only a sketchy overview of the field can be given. Eyler, Ausloos and Lias434 showed that the C=0 bond in ketones can be split by CF3+, C2F5+ and CC13+, e.g. the reaction... 

Another conventional ionization technique termed chemical ionization (Cl), utilizes a reagent gas (such as isobutane, methane, ammonia) to form reagent ions (Rif) which can undergo ion-molecule reactions with the compound of interest to form protonated molecules. 

The selected primary ions can also be characterized by ion molecule reactions with the FTMS-2000 dual cell and/or surface induced reactions (48). Reactions specific for particular functionalities can be used to count the number of these in a primary ion such as the number of hydrogen atoms that can be exchanged with a deuterium-containing species (59). Further, their position may well be distinguished by the reaction s effect on fragment ions in MS-II spectra. 

Other ion-molecule reactions with methane will occur in the plasma, such as... 

As already discussed, negative ions can also be formed through ion-molecule reactions with one of the plasma ions. These reactions can be an acid-base reaction or an addition reaction through adduct formation. 

Product formation in a radiolysis system is often complex as a result of the many different species present. There are, however, three main types of reactive species excited molecules, ions and free radicals. The excited molecules and ions are generated directly, while the free radicals are formed by dissociation of the excited molecules or ions. The reactions of these three species account for the products. Decomposition or combination and disproportionation are the main reactions of free radicals in the absence of inhibitors. Excited molecules can lead directly to molecular products by dissociation or to higher products by dimerization reactions. Ionic species can yield molecular products by dissociation (if excited) or by ion-molecule reactions with the formation of a new ion in each case. Neutralization of the positive ions by electrons or by negative ions produces additional molecular products. 

In negative-ion mode, a similar treatment holds, with snperoxide as an important initial ionic species, which is involved in ion-molecule reactions with the mobile-phase constitnents. The proton-transfer reaction leading to the deprotonated analyte molecnle [M-H] ... 

R.R. Ogorzalek Loo, J.A. Loo, H.R. Udseth, J.L. Fulton, R.D. Smith, Protein structural effects in gas phase ion-molecule reactions with diethylamine. Rapid Commun. Mass Spectrom., 6 (1992) 159. 

ANI +. Structure identification was based on ion-molecule reactions with dimethyl disulfide the attachment of a methylthio radical, which usually characterized distonic... 

Figure 4 In-source CID of P-BrC6H4N2+ in tube lens region of the LCQ followed by ion-molecule reactions with reactive gases derived from the ESI solvent (CH3CN). Ions are labeled according to Scheme 12.

RAJ O Hair, GE Reid. Derivatization of protonated peptides via gas phase ion-molecule reactions with acetone. J Am Soc Mass Spectrom 11 244-256, 2000. 

Such behaviour clearly contrasts with the case of 4-iodoaniIine, where protonation in a chemical ionization source occurred not only on the ring but also on the nitrogen atom . Nitrogen protonation was indicated by ion-molecule reactions with dimethyl disulphide consecutive to collisional dehalogenation (FT-ICR experiments) or by an increase in the intensity of the peak at mjz 76 following high-energy collisional activation . 

Only few investigations have been published on the gas-phase ion chemistry of host-guest complexes of calixarenes. With the advent of ESI mass spectrometry, especially when combined with ion-trap and FT-ICR mass spectrometry, this field has started to be developed. Binding selectivities of alkali metal ions to cahxarene-based crown ethers and open-chain ethers have been studied , the inclusion of neutral guests into the protonated resorcarene-based cavitand hosts by gas-phase ion-molecule reactions with amines have been studied and the formation of capsules from various calixarene tetraether derivatives and alkylammonium ions as ionic guests (notably enabling their detection by mass spectrometry) have been described recently . ... 

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