Energetic neutral atom

The Ion source can be of a number of different types capable of making Ions of a large variety of atoms. One may also bombard the surface with a beam of energetic neutral atoms or a photon beam... 

Mauk B. H., Mitchell D. G., Krimigis S. M., Roelof E. C., and Paranicas C. P. (2(X)3) Energetic neutral atoms from a trans-Europa gas torus at Jupiter. Nature 421, 920-922. 

There are numerous other ionization methods, but they have limited applications. Fast atom bombardment (FAB), also known as liquid secondary ion mass spectrometry (LSIMS), was one of the early methods developed for the ionization of polar molecules. FAB is based on bombarding analytes in a matrix of low volatility, such as glycerol, with accelerated energetic neutral atoms (argon or xenon) or ions (cesium) that wiU sputter [M + H]+ ions from the surface. Although of major importance during its heyday, FAB has been superseded by ESI. 

Fast atom bombardment FAB desorption/iQiuzatiQn from solids and liquids by a beam of energetic neutral atoms [11,12]... 

Figura 1 Schematic of SNMS analysis. Neutral atoms and molecules sputtered from the sample surface by energetic ion bombardment are subsequently ionized for mass spectrometric analysis.

Tables in reference sources often give electron affinities as positive values when the negative ion is more stable than the neutral atom. This convention is contrary to the sign convention for other energetic processes, which uses negative values when energy...

Positive ions start to capture electrons from the medium when their velocity is comparable to that of an electron in an ls-orbital around itself. On further slowing, at first the captured electron is soon lost, and then another electron is captured. Thus cycles of capture and loss continue until it is energetically impossible to lose the captured electron. If the incident particle is multiply charged, another charge exchange cycle will soon be set up, and so on until the particle is reduced to a neutral atom. 

Conceptually, the cross section is used as a measure of the probability of interaction between charged particles (and energetic neutrals) and atomic and molecular targets. ... 

The ionization energy of Ar is 15.8 electron volts (eV), which is higher than those of all elements except He, Ne, and F. In an Ar plasma, analyte elements can be ionized by collisions with Ar+, excited Ar atoms, or energetic electrons. In atomic emission spectroscopy, we usually observe the more abundant neutral atoms, M. However, the plasma can be directed into a mass spectrometer (Chapter 22), which separates and measures ions according to their mass-to-charge ratio.17 For the most accurate measurements of isotope ratios, the mass spectrometer has one detector for each desired isotope.18... 

Both effects can be studied quite independently in molecular clusters adding more and more neutral atoms (often Ar) around the reactive precursor can change the thermal bath environment, only weakly changing the energetics. On the other hand, more polar molecules will gradually change the energetics of the reactive... 

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