Ionizable species separation

Ion Implantation Systems. An ion implantation system is used to accelerate ionized atomic or molecular species toward a target sample. The ionized species penetrates the surface of the sample with the resulting depth profile dependent on the implanted species mass, energy, and the sample target s tilt and rotation. An implanter s main components include an ionizer, mass separator, acceleration region, scanning system, and sample holder (168). 

No mention of throughput was made. Measurement of pKa by UV after separation by CE has been described for acids [41] and bases [42], and while this method only requires small sample quantities, the rate of throughput is currently about 20 samples per day [23, 43], A rate-limiting step in the CE method is the need to make separate experimental runs at different buffered pH values in order to determine the relative concentration of ionized species at each pH. 

We can now write the complete or total ionic equation for each of the reactions. All we need to do for this step is to write the separated ions and non-ionized species on one line ... 

The interaction of an electron with a molecule is described as a collision or impact, although the electron is so small that there is no collision in the usual sense of the word. The collision process may be termed elastic (the electron is merely deflected), inelastic (energy is transferred from the electron to the molecule), and superelastic (energy is transferred from the molecule to the electron). Electron-impact ionization is an example of an inelastic collision. The energy imparted to a molecule during an inelastic collision can lead to rotational, electronic, and vibrational excitation with or separate from ionization. Further, multiple-electron excitation can occur followed by autoionization, and the latter process has been shown to lead to a substantial fraction of total ionized species in many cases (S. Meyerson et al., 1963). Thus, an electron of energy 20 eV may lead to any of the above excitations of a molecule. The gas pressures used in a mass spectrometer and the density of electrons in the electron-beam are such that multiple electron-molecule interactions leading to ionization are improbable. 

For nonionized compounds, or to change selectivity for ionized compounds, buffer additives such as micellar sodium dodecyl sulfate (SDS) or an octane/ butan-l-ol/SDS microemulsion may be used. For nonionic compounds, separation is based on distribution between the buffer and the charged additive, which moves at a different velocity than the background electrolyte. For charged species, separation is based on both the partitioning and the electrophoretic mobility of the sample components. Samples that are not soluble in aqueous media may be separated in organic solvents such as methanol or acetonitrile containing a conductive salt. ... 

In pyridine, ionized species will be present mainly as solvent-separated ion pairs because pyridine is a strong EPD medium, but a weak dissociating medium. DMSO is both a strong EPD and a strong dissociating medium and therefore ionized species will be present as free ions to a much greater extent 64, 49, 50, 97). 

This new separations method (CZE) is rapidly gaining distinction for separating a wide range of ionizable species because of its very high resolution (32). The usefulness of CZE for characterizing silica sols has been explored (33). 

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