THE TANDEM FLOWING AFTERGLOW-SIFT-DRIFT: DEVELOPMENTS AND APPLICATIONS TO GAS PHASE ION CHEMISTRY

摘要

This thesis describes the detailed design of the Tandem Flowing Afterglow-SIFT-Drift and applications of this technique and other flow tube techniques to gas phase ion chemistry. Chapter II discusses the design characteristics and performance of the new instrument. The versatile ion source and high sensitivity and resolution of the instrument allows generation and study of a variety of ions including highly reactive ions (CH$sb2sp-$), solvated ions (HO$sp-$(H$sb2$O)), ions which must be synthesized by a series of ion molecule reactions (C$sb3$H$sb3$N$sb2sp-$) as well as isotopically labelled ions ($sp{37}$Cl, $sp{34}$S, $sp{13}$C, $sp{18}$O) from unenriched precursors. The experimental procedure and data analysis are described in Chapter III.;The kinetics of $sp{18}$O$sp-$ exchange reactions with a variety of neutral reagents are investigated in Chapter IV. Exchange is observed even in cases where an efficient associative detachment channel is operative (O$sp-$/CO, O$sp-$/SO$sb2$).;The chemistry of CH$sb2sp-$ is described in Chapter V. This very basic radical anion exhibits a propensity to proton abstract and associatively/reactively detach. Reactions forming formaldehyde, ketene, and ketene-like molecules are also observed.;The acidities of a series of $beta$-branched and polycyclic hydrocarbons are probed in Chapter VI using the kinetic acidity method developed by DePuy, et al. (1984). A preliminary investigation of a more sensitive extension of this method is also presented.;The chemistry of diazomethyl anion is described in Chapter VII. Addition with loss of nitrogen is a common reaction. The acidity of diazomethane is bracketted as 373 $pm$ 4 kcal/mol and the electron affinity of diazomethyl radical is estimated to be $sim$48 kcal/mol.;Kinetics of $sp{37}$Cl$sp-$ exchange reactions with a variety of reagents are discussed in Chapter VIII. Exchange with CH$sb3$Cl is not observed at room temperature and is very inefficient at higher kinetic energies up to 1.4 eV(CM). The $sp{37}$Cl$sp-$ reaction with HCl appears to proceed through a long-lived complex.;The product ion of the O$sb2sp+$ + CH$sb4$ room temperature reaction is identified as methylene hydroperoxide. A comprehensive study of the chemistry of this cation is discussed in Chapter IX. Chapter X presents a qualitative and semi-quantitative model for the reaction mechanism for O$sb2sp+$ + CH$sb4$ at room temperature.