Chapter 8 - Chapter 8 An Introduction to Optical Atomic...

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Chapter 8 An Introduction to Optical Atomic Spectroscopy Atomic Spectroscopic methods are used for elemental analysis for identification and quantitation. Need free atoms in the gas phase for atomic analysis. The elements present in the sample are converted to gaseous atoms or elementary ions by a process called atomization . The ultraviolet/visible absorption, emission or fluorescence of the atomic species in the vapor is measured.
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Atomic spectroscopy are of 3 types – atomic absorption (AA), atomic emission (AE) and atomic fluorescence (AF) methods 1. Atomic Absorption(AA): In a hot gaseous medium, atoms are capable of absorbing radiation of wavelengths characteristic of electronic transitions from ground to higher excited states. Typically atomic absorption spectrum consists of resonance lines which are the result of transitions from the ground to upper levels.
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2. Atomic Emission (AE): At room temperature, essentially all of the atoms of a sample of matter are in the ground state. Excitation to higher orbitals can be brought about by the heat of a flame, a plasma, an electric arc or spark. Its return to the ground state is accompanied by emission of a photon of radiation.
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3. Atomic Fluorescence (AF): Atoms or ions in a flame can be made to fluoresce by irradiation with an intense source containing wavelengths that are absorbed by the element. The observed radiation is most commonly the result of resonance fluorescence involving transitions from excited states returning to the ground state.
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Atomic Line Widths The widths of atomic lines are of considerable importance in atomic spectroscopy. Narrow lines are highly desirable for both absorption and emission
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This note was uploaded on 05/06/2010 for the course CHEM 4414 at Arkansas Tech.

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Chapter 8 - Chapter 8 An Introduction to Optical Atomic...

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