SIFT apparatus

K has been identified as CFl200I-I from its chemistry the reaction mechanism is insertion [115], Collision-induced dissociation (in a SIFT apparatus, a triple-quadnipole apparatus, a guided-ion beam apparatus, an ICR or a beam-gas collision apparatus) may be used to detemiine ligand-bond energies, isomeric fomis of ions and gas-phase acidities. 

A sehematie diagram of a SIFT apparatus is shown in figure Bl.7.12. The instrument eonsists of five basie regions, the ion soiiree, initial quadnipole mass filter, flow tube, seeond mass filter and finally the deteetor. The heart of the instrument is the flow tube, whieh is a steel tube approximately 1 m long and 10 em in diameter. The pressure in the flow tube is kept of the order of 0.5 Torr, resulting in earrier gas flow rates of... 

Figure Bl.7.12. A schematic diagram of a typical selected-ion flow (SIFT) apparatus. (Smith D and Adams N G 1988 The selected ion flow tube (SIFT) studies of ion-neutral reactions Advances in Atomic and Molecular Physics vol 24, ed D Bates and B Bederson p 4. Copyright Academic Press, Inc. Reproduced with pennission.)...

Fig. 8. Variation of the rate coefficient with temperature as measured with the CRESU apparatus for the reaction of N+ with ammonia [50]. The open circles represent early CRESU (at Meudon) results [52] while the solid circles are newer CRESU (at Rennes) results [50]. The open square is a room-temperature result obtained by Adams et al. [53] with a SIFT apparatus. The solid line is a theoretical prediction by Troe using the statistical adiabatic channel model [54]...

It is worth mentioning that the metaphosphate anion (PO3 ) is readily observed in the negative ion mass spectra of many organophosphorus esters Further, its ion-molecule reactions have been studied in a SIFT apparatus. Interestingly, the CA mass spectra of... 

Zhang X, Kato S, Bierbaum VM, Nimlos MR, Ellison GB. Use of a flowing afterglow SIFT apparatus to study the reactions of ions with organic radicals. J Phys Chem A. 2004 108 9733-41. 

To study a particular ion-molecule reaction, a reactant gas is introduced at a measured flow rate into the carrier gas. Then by measuring the count rates, 7, of the reactant and product ions using the downstream mass spectrometer and relating them to the number destiny of the reactant gas in the carrier gas, the k for the reaction (following Eqn [1]) and the ion products can readily be determined (see Figure 2). Some SIFT apparatuses can be operated over the wide temperature range 80-600 K. Constructional details for a SIFT are given in some of the cited reviews. 

Figure 1 Schematic representation of a SIFT apparatus. One form of Venturi-type inlet is shown in the upper-left part of the diagram. The vacuum jacket facilitates operation at high and low temperatures.

Using SIFT apparatuses, the rate coefficients and products ions for a large number of positive ion-neutral and negative ion-neutral reactions have been studied in several laboratories around the world. They include the bimolecular reactions of doubly... 

Figure 8 A SIFT apparatus configured for trace gas analysis, with the stable discharge ion-source for H3O+, NO+ and 0+ ions, and a single air/breath sample inlet port. 

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