Formation of association ions in the photoionization of alkyl halides

Abstract

The methyl and ethyl chlorides and bromides, as well as methyl iodide, were photoionizcd in the vacuum ultraviolet at 300 K in a mass spectrometer over the pressure range 0.5 to approximately 100 millitorr. Under these conditions, stabilized parent ion dimers are found in CHaBr, CHBI, and C2H5Br, but not in the chlorides. Lower limits for the dissociative lifetimes of the ion-molecule collision complexes were estimated and are as follows: (CH3Br)z+, 1.6 ps; (CH31)2+, 1.9 p s ; and (CZHSBr)2+, 5.4 p s . An increase in photon energy (internal energy content of the reactant ion) decreases the dissociative lifetime of the collision complex in CHaI.

The gas phase reactivity of the dimethylchloronium ion with alkylbenzenes

“…At pressures greater than 50 mTorr this ion disappears completely, being replaced by the halonium ion (6,7) [l] CH3CI+ + CH3C1 + CH3CIH+ + CH2C1 [2] CH3CIH+ + CH3CI + CH3C1CH3+ + HCI Figure 1 shows both a gc trace and the monitored CH33SClCH3+ ion signal for a sample containing fluorobenzene, toluene, ethylbenzene, and mesitylene in roughly equal concentrations. The same relative decreases in ion signal were observed when CH337ClCH3+ was monitored.…”

Nanochemistry: Iron Cluster Reactions with Methyl Iodide

“…Following dissociation, intracluster chemistry results in a range of final cluster products. Both neutral and ion−molecule chemistry has been observed. − In the latter case, comparisons may be made with electron impact induced reactions in cluster beams , and in older collisional association studies. , Finally, laser ablation mass spectrometry of cryogenic, condensed phase, methyl iodide films yields chemical products similar to those observed in the cluster studies and illustrates the utility of comparing the gas-phase cluster environment to that of the condensed phase. − Some negative ion studies of methyl iodide clusters have also appeared. , …”