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reduces the pressure in the first chamber to a few microns, and in the second chamber to about 10-5 mm
of mercury. During passage through these chambers, the solvent evaporates from the wire, leaving the
solute as a thin film coated on the wire surface. A current of a few milliamperes is passed continuously
through the wire, which only becomes hot when it enters the high vacuum of the ion source, where it
can no longer lose heat to its surroundings. The temperature of the wire rises rapidly to about 250°C in
the ion source, vaporizing the sample directly into the electron beam. The wire leaves the ion source
through the same type of vacuum lock as it entered, i.e. via a second pair of differentially pumped
chambers. A detailed diagram of the vacuum locks is shown in Figure 9.10.
Figure 9.10
The Wire Transport Interfaces
