Inorganic ions, laser ionization mass spectrometry

In contrast, the LA-ICP-MS (in comparison to laser ionization mass spectrometry (LIMS) where the ion source operates under high vacuum conditions) at present, in spite of the disadvantage of a higher polyatomic ion formation rate, uses an argon plasma ionization at normal pressure - a promising inorganic mass spectrometric technique for trace, isotope and surface analysis which will... 

LASER IONIZATION MASS SPECTROMETRY OF INORGANIC IONS... 

Struyf, H., Van Vaeck, L., Van Grieken, R. (1996) Desorption/ionization of inorganic compounds in Fourier transform laser microprobe mass spectrometry with external ion source. Rapid Communications in Mass Spectrometry, 10, 551-561. 

The ion source is an essential component of all mass spectrometers where the ionization of a gaseous, liquid or solid sample takes place. In inorganic mass spectrometry, several ion sources, based on different evaporation and ionization processes, such as spark ion source, glow discharge ion source, laser ion source (non-resonant and resonant), secondary ion source, sputtered neutral ion source and inductively coupled plasma ion source, have been employed for a multitude of quite different application fields (see Chapter 9). 

Most analytical studies using FT-ICR mass spectrometry, where ions have been produced inside (or just outside) the analyzer cell, have used lasers as ionization sources. Other than some very limited Cs secondary ion mass spectrometry (SIMS) studies [77], most research utilized direct laser desorption to form various organic [78] and inorganic [79] ions, including metal [80] and semiconductor [81] (including carbon) clusters. More recently matrix assisted laser desorption ionization (MALDI) has been used to form ions of high molecular weight from polymers [82] and many classes of biomolecules [83]. 

A variety of other techniques based on the reaction of ionizing agents with sample molecules are readily available to the mass spectrometrist. EAB and secondary ion mass spectrometry (SIMS) are used to analyze nonvolatile solids and use respectively energetic atoms and ions to achieve sputtering of the sample including ionization. Laser and PI and ED/EI are also well-established techniques. Inorganic materials may be ionized by arc discharge. 

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