Electron spray ionisation

Ir (CH2CN)(Me3tpa)] + in acetonitrile and [Ir" (CH2COMe)(Me3tpa)] + in acetone has been detected with ESI-MS (ESI-MS = electron-spray ionisation mass spectrometry). 

Atmospheric pressure spray with electron impact ionisation Atomic plasma emission spectrometry... 

The sample molecules can be ionised by one of several techniques. In electron impact ionisation, (El), electrons are fired at the sample molecules, whereas in chemical ionisation, (Cl), the sample molecules are collided with a reactive gas. The sample can also be bombarded with argon atoms (fast atom bombardment, FAB) or the dissolved sample can be sprayed into an electric field electrospray ionisation, ESI). Furthermore, the sample can be co-crystallised with a matrix and then ions can be generated by exposure to photons (matrix assisted laser desorption ionisation, MALDI). 

The main difference between ESI and APCI is that, in APCI, the ions are formed when the analyte molecules in the gas phase interact with electrons discharged from a corona needle (see Figure 5.18). As with ESI, the eluent is sprayed through a heated vaporiser at atmospheric pressure. The heat from the vaporiser causes the liquid to vaporise and the resultant solvent molecules, now in the gas phase, to be ionised by the electrons from the corona needle. These ions then transfer charge to the analyte molecules through chemical reaction (hence the name atmospheric chemical ionisation ). These ions, as in ESI, pass through a capillary and pass into the mass analyser. 

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