Selected Ion Flow Drift Tube

Figure A3.5.7. Schematic diagram of a selected ion flow drift tube with supersonic expansion ion source.

In obtaining experimental information about the isomeric forms of ions, a variety of techniques have been used. These include ion cyclotron resonance (ICR),31 flow tube techniques, notably the selected ion flow tube (SIFT),32 and the selected ion flow drift tube (SIFDT)32 (and its simpler variant33), collision induced dissociation (CID),10,11 and the decomposition of metastable ions in mass spectrometers.13 All of these techniques are mentioned in the text of Section in whore they have provided data relevant to the present review. 

The temperature dependence of the kinetic isotope effect for the gas-phase S 2 reaction of CL with MeBr was examined in a variable-temperature selected ion flow drift tube. The results were then interpreted by a molecular modeling study250. 

The study of internal energy effects in the HTFA is a continuation of work that was started at lower temperatures using the variable temperature selected ion flow drift tube (VT-SIFDT). That data has been summarized previously and several trends were noted. The HTFA comparisons taken as a function of translational energy allow us to verify those trends and look for new ones which become apparent due to the extended energy range. Data from other experiments that probe internal energy effects, sometimes with quantum state resolution, are now available and can be included in the comparison. 

The effects of energy on ion-molecule rate processes have been investigated by a variety of methods. The influence of reactant translational energy, as studied by SIFDT (selected ion-flow drift-tube) techniques in swarm experiments, by ICR, and by beam and other single-collision techniques, is reviewed in other parts of this chapter or of this book. In this section, we will concentrate specifically on the influence of reactant internal energy on ion-molecule reactions. There are basically two sources of data that address this problem ... 

Figure 2 Rate coefficients for the reaction of Ol with methane measured as a function of average kinetic energy at several temperatures in a variable-temperature selected-ion flow drift tube (VT-SIFDT). Also shown are data taken with a high-temperature flowing afterglow (HFTA) and a drift tube. Reproduced with permission from Viggiano AA and Morris MA (1996) Journal of Physical Chemistry 100 19227-19240.

Fairly, D. A., Milligan, D. B., Freeman, C. G. et al. (1999) Competitive association and charge transfer in the reactions of NO+ with some ketones a selected ion flow drift tube study. Int. J. Mass Spectrom. 193,35. 

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