Polyatomic materials

The simplest calculation of radiation damage involves only monatomic materials and has been described by many authors (17—20). For polyatomic materials, a calculation procedure for estimating damage energy from ion implantation has been outlined (8). The extension of this formalism (8) to direct calculations of damage energies in polyatomic materials has been addressed by several authors (11,21—24). 

In Sect. 7.2 the concept of a replacement collision was introduced. A replacement collision was possible if a PKA had sufficient energy to displace an atom from its lattice site but was left with energy less than Ed and fell into the vacated site it just created. Early computer simulations of the irradiation process showed that the number of such replacement events greatly exceeded the number of permanent displacements left in the lattice. While such events have little influence on monatomic materials, replacement collisions can produce considerable disorder in ordered polyatomic materials. 

Today, secondary ion mass spectrometry (SIMS) is frequently used for analysis of trace elements in solid materials, especially in semiconductors and in thin films [62,63]. Primary beam species useful in SIMS include Cs+, Oj, O, Ar+, and Ga+ at energies from 1-30 keV. The bombarding primary ion beam produces monatomic and polyatomic particles of sample... 

Russel WA, Papanastassiou DA, Tomhrello TA (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochim Cosmochim Acta 42 1075-1090 Sakata KI, Kawahata K (1994) Reduction of fundamental polyatomic ions in inductively coupled plasma mass spectrometry. Spectrochim Acta Atom Spectrosc PartB 49 1027-1038 Siehert, C, Nagler, TF, Kramers JD (2001) Determination of molybdenum isotope fractionation by doublespike multicollector inductively coupled plasma mass spectrometry. Geochem Geophys Geosyst 2 2000GC000124... 

Many elements can give rise to more than one elementary substance. These may be substances containing assemblages of the same mono- or poly-atomic unit but arranged differently in the solid state (as with tin), or they may be assemblages of different polyatomic units (as with carbon, which forms diamond, graphite and the fullerenes, and with sulfur and oxygen). These different forms of the element are referred to as allotropes. Their common nomenclature is essentially trivial, but attempts have been made to develop systematic nomenclatures, especially for crystalline materials. These attempts are not wholly satisfactory. 

ORIT in the Photoexcitation Spectrum in Pyrazine The ORIT phenomenon, where a photoabsorption transparency window occurs at certain frequencies due to interference between material waves within a molecule, is briefly considered here. Though ORIT is known for small systems [25,27], it has not been investigated for polyatomic molecules where overlapping resonances... 

Investigations of cluster formation serve to explain the evaporation and atomization of sample material and ion formation processes. A further aim of cluster research is to find out under what conditions cluster or polyatomic ion formation can be influenced in order to avoid disturbing interferences and decrease the detection limits of elements. On the other hand, polyatomic ions have also been used as analyte ions for analysis, e.g. the application of MCs+ and MCs2+ dimeric and trimeric ions as analyte11 or of cluster primary ion beams (e.g., of bismuth and gold primary clusters)15 16 by the bombardment and sputtering of a solid surface in SIMS.17-21 Especially in SIMS, a multitude of cluster ions with high ion formation rates are observed.18 22 23... 

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