Investigations on cluster and molecular ion formation by plasma mass spectrometry

The formation of molecular and cluster ions of different inorganic materials in plasma mass spectrometry – spark source mass spectrometry (SSMS), radiofrequency glow discharge mass spectrometry (rf GDMS), laser ionization mass spectrometry (LIMS), inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) – was investigated and compared. Similar abundance distributions of cluster ions were observed for a graphite sample, for boron nitride/ graphite and for metal oxide/graphite mixtures using different plasma mass spectrometric methods. A correlation of intensities of metal argide ions in ICP-MS with their bond dissociation energies was used to estimate unknown dissociation energies of molecular ionic species. For the elements of the 2nd or 3rd period in the periodic table, the intensities of most argon molecular ions (ArX⁺) measured by ICP-MS rise with increasing atomic number in a similar manner to the theoretically calculated bond dissociation energies of argon molecular ions.