Octopole ion beam “guide

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... 

An octopole ion beam guide is being constructed, which will permit us to study collision energies down to 0.1 eV. In addition, we have made new position sensitive detectors, which will allow us to measure complete energy and angle differential cross sections. We anticipate that future results will be even more exciting than those we have described in this paper. 

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... 

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]...

Fig. 1.6. Beam directioning during soft-landing the focusing octopole ion guide. The schematics present a 3D view of the newly constructed conical octopole guide. Eight rods shaped as truncated cone (diameter rejuvenates from 3 to 0.5 mm) are arranged in a conical geometry. Two Teflon plates at the ends with four carriage bolts and two metal collars (in the cylindrical part) keep the conical geometry. The ion entrance orifice opens 9 mm in iimer diameter and the exit focuses to around 2-mm spot size [74]...

TCID experiments employ tandem mass spectrometers of various types. Guided ion beam (GIB) instruments use a radio frequency octopole in the interaction region for high-efficiency collection of scattered products and low-energy ions. These instruments typically use a magnetic sector or Wien filter for initial mass analysis and... 

A special solution for obtaining very slow ions is the so-called trapped ion beam technique, a method which has been described in Ref. 10. Using an ion guide, e.g. an octopole, together with meV potential barriers, one can store nearly monoenergetic ions at meV laboratory energies. So far this method has been used only in a few cases, e.g. for He+ stored in O2. For this system, experiments have been performed with He+ ions trapped at... 

Tosi, P Fontana, G. Longano, S. Bassi, D. Transport of an ion beam through an octopole guide operating in the rf-only mode. Int. J. Mass Spectrom. Ion Processes 1989, 93, 95-105. 

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