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Source Conditions

The electron impact ionisation of the precursor gas can create molecular ions in excited electronic, vibrational and rotational states, especially for fragment ions e.g. GeH+ from GeH4. Due to the short flight time of the ions through the apparatus ( $\approx 10^{-6}$ seconds) and a low pressure in the flight region (10-8 torr), there are few opportunities for collisional relaxation thereby allowing excited states of a molecular ion to be probed.



Tim Gibbon
1999-09-06