Guided ion beam

In essence, a guided-ion beam is a double mass spectrometer. Figure A3.5.9 shows a schematic diagram of a griided-ion beam apparatus [104]. Ions are created and extracted from an ion source. Many types of source have been used and the choice depends upon the application. Combining a flow tube such as that described in this chapter has proven to be versatile and it ensures the ions are thennalized [105]. After extraction, the ions are mass selected. Many types of mass spectrometer can be used a Wien ExB filter is shown. The ions are then injected into an octopole ion trap. The octopole consists of eight parallel rods arranged on a circle. An RF... 

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. 

Another instrument used in physical chemistry research that employs quadnipole mass filters is the guided ion beam mass spectrometer [31]. A schematic diagram of an example of this type of instrument is shown in figure B 1.7.13. A... 

Using a guided ion beam instrument the translational energy dependent reaction cross sections of endothemiic fragmentation processes can be detemiined [32]. Modelling these cross sections ultimately yields their energy tln-esholds and a great deal of valuable themiochemical infomiation has been derived with this teclmique. Precision of 0.2 eV can be obtained for reaction tln-esholds. Bimolecular reactions can also be studied and reaction enthalpies derived from the analysis of the cross section data. 

Guided ion beam tandem mass spectrometry has also been employed to study the reaction of Ni+ with CS2 and COS.2410 The ground state ion Ni+ undergoes endothermic reaction to form NiS+ in both cases, as well as NiCS+ and NiCO+, respectively. Threshold values for the reactions and bond dissociation energies for the products have been determined. 

A parallel investigation on the binding of alkali metal cations to nucleobases, employing guided ion beam mass spectrometry, has recently been reported by Rodgers and Armentrout . ... 

Gibbs free energies of formation, 33 127 GIBMS, see Guided-ion-beam mass spectrometry... 

Guanosine nucleotide, redox pathways, 43 129 Guided-ion-beam mass spectrometry, metal-0X0 systems, 44 323 Gutmann donor number, 34 174 Gypsum... 

The Met+—L bond dissociation energies were measured for some Zn-containing gas phase cations using different methods ". Armentrout reviewed guided ion beam studies of transition metal-ligand thermochemistry and reported the following... 

Guided-ion-beam mass spectrometry (GIBMS) was used to study the reaction of CoO+ with CH4 and with D2 (.223). The exothermic reaction with methane, Eq. (4), was found to have an activation barrier of... 

Further support for the instability of SiH4+" comes from studies of the charge transfer reactions of a variety of small ions with SiFLt11. Although almost resonant charge transfer was achieved in the reaction of SiHt with Xe+ (AIE = 0.08 0.21 eV), no SiH4+ cations were observed in these guided-ion beam studies. 

The reactions of atomic silicon cations with a large variety of neutral molecules have been reported and summarized in reviews focussed on the kinetic, energetic and the mechanistic study of these reactions by selected-ion flow tube (SIFT)10 and guided ion beam techniques11. 

Dissociation of halomethanes, particularly CF4, by collisions with rare gas active species has also been studied under various experimental conditions. The cross sections of each product ion in the M+/CF4 (M = Ar, Ne, He) reaction system from thermal to 50 eV have been determined using guided ion-beam techniques72. It was found that the energy dependence of the cross sections can be understood by considering the energies needed to access specific electronic states of CF4+ 72. 

Armentrout PB (1992) Thermochemical measurements by guided ion beam mass spectrometry. In Adams N, Babcock LM (eds) Advances in gas phase ion chemistry, vol 1. JAI Press, Greenwich, CT, p 83... 

Keywords. Bond dissociation energies, Collision-induced dissociation, Guided ion beams, Reaction barriers, Thermochemistry... 

GIBMS Guided ion beam tandem mass spectrometer... 

In a guided ion beam experiment, reactant ions are created in the source region, mass selected by a mass spectrometer (a magnetic sector in our instruments), decelerated to a desired kinetic energy, and injected into a radiofrequency (rf) octopole ion beam guide [10,11]. This device comprises eight rods cylindrically surrounding the ion beam path. Opposite phases of an rf potential... 

Fig. 3. Schematic diagram of the guided ion beam tandem mass spectrometer, double octopole configuration. Pumping speeds are shown. Ion sources available are listed and the microwave discharge source is shown. Adapted from [9]...

Collision-induced dissociation of protonated indole with Xe has been studied as a function of kinetic energy using guided ion beam tandem mass spectrometry techniques <2007MI388>. 

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