Categories of exhibits
Fast atom bombardment probe
Exhibit no. 103
In some mass spectrometry techniques, the sample needs to be placed directly into an ion source operating under low pressure. To insert the sample without breaking the vacuum, a device called a vacuum lock is used. The lock usually consists of differentially pumped chambers separated by a ball valve. A rod probe, with the sample loaded on its tip, is inserted into the lock chamber. When the pressure in the chamber equalizes with the pressure in the ion source, the valve is opened and the probe is pushed fully into the ion source. Insertion probes are used for various ionizations including EI/CI, FD, or FAB.
The exhibit is a fast atom bombardment (FAB) probe for the ZAB-EQ sector mass spectrometer manufactured by VG Analytical Ltd. in 1986. In FAB ionization, the sample dissolved in glycerol or another matrix is exposed to a beam of high-energy xenon atoms, causing molecules at the surface of the matrix to be ejected and ionized. The probe consists of a handle, a probe shaft, and a probe tip with a stainless-steel target to which a mixture of sample and matrix was applied. A micrometer on the handle was used for adjusting the distance of the target from the atom beam. As the micrometer was turned clockwise the probe shaft was lengthened.
