Term
| X-ray Florescene is mostly used for: |
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Definition
| Major element analysis and some trace analysis. |
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Term
| Define wavelength dispersive spectrometer. |
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Definition
| This system depends on the dispersive power of a crystal. |
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Term
| Define energy dispersive spectrometer |
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Definition
| This system depends upon the proportional electronic response characteristics of photon counters. |
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Term
| What is XRF Bulk Technique capable of? |
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Definition
| Major element analysis, some trace; a destructive but relatively cheap and accessible process |
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Term
| What is electron microbeam process capable of? |
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Definition
| Capable of major and some trace element analysis, NON-destructive, expensive! and relatively inaccessible. |
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Term
| X-ray interaction with matter |
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Definition
| When an element is bombarded with high energy x rays, the orbital electrons interact with the x-rays via a TRANSFERENCE OF ENERGY to the atom; the atom will return to its lowest energy condition by the emission of radiation. |
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Term
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Definition
| The energy required to ionize the k-shell electron; an x-ray photon with an energy just below the absorption edge wil be transmitted, and one with an energy above the absorption edge will be absorbed. |
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Term
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Definition
| The probability that an atom in its excited state will emit an x-ray photon in its first transition rather than an Auger electron. |
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Term
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Definition
| Occurs when an x-ray photon collides and is scattered without a loss of energy and wavelength is therefore unchanged. |
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Term
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Definition
| The frequency of emission is not the same as that of incident. |
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Term
| Excitation Source for X-rays |
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Definition
| Any high energy particle may be used: sealed x-ray tubes & high voltage generator, electron microprobes, protons, ions, gamma rays |
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Term
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Definition
| Some include: NaI, Flow Proportional Counters, Solid State SiLi, GeLi, Ge |
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Term
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Definition
| Slow dissipation of positive ion sheath has the effect of preventing further avalanches, leading to dead time. |
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Term
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Definition
| In bulk XRF work the intensity of a line is not directly proportional to concentration, but is affected by all other elements present in proportion to their concentration. |
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Term
| Possible matrix corrections |
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Definition
- Mathematical corrections
- Choice of standards
- Matrix matching |
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Term
| Sample prep: Fused glass beads characteristics |
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Definition
- Major elements
- Small amount of rock
- Heavy absorber
- 100 micron powders |
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Term
| Sample prep: Pressed Powder Pellets |
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Definition
- Larger amount of rock
- Trace elements are discernible
- Resin binder
- 250 micron powder |
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Term
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Definition
| Weigh out a known quantity of rock into unglazed porcelain boat - place in furnace - ignition of sample drives off volatiles - CO2 is collected by soda asbestos. H2O is collected by anhydrous magnesium perchlorate. FeO must be determined by titration. |
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