Energetic beam analytical techniques

ToF-secondary ion mass spectrometry (ToF-SIMS) is a versatile surface analytical technique that provides detailed information about molecular composition and imaging of surface monolayers with high sensitivity and resolution. In a typical SIMS sample, surfaces are exposed to a beam of energetic primary ions or atoms (5—25 keV), which results in the emission of secondary ions including quasimolecular ions, atoms, and molecules (Benninghoven, 1994). The secondary ions formed as a result of this... 

GC/MS analyses most often employ one of two complementary ionization processes, electron ionization (El) or chemical ionization (Cl). This is because both El and Cl are gas phase ionization phenomena and are therefore well suited to interface with a separation technique (GC) that is also accomplished in the gas phase. The extractables profiles shown in Figs. 3-5 along with the Abietic Acid GC/MS analysis shown in Fig. 1, were acquired using GC/MS with El. The El ionization process is based on the interaction of an energetic electron beam (70 eV) with neutral analyte molecules in the gas phase, producing a radical cation, or molecular ion (M+ ) that can undergo fragmentation in the gas phase after redistribution of excess... 

Analyte molecules must first be ionized in order to be attracted (or repelled) by the proper magnetic or electrical fields. There are numerous ionization techniques, but electron impact (El) is the oldest, most common and most simple. The ionization source is heated and under vacuum so most samples are easily vaporized and then ionized. Ionization is usually accomplished by impact of a highly energetic (70 ev) electron beam. 

---