Chapter 8 and 9 (and a little 10)

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Chapter 8 and 9(and a little 10)

• Atomic Spectroscopy
• Instrumental Analysis
• Spring 2011

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I. Optical Atomic Spectra

• Again, these are going to be line spectra
• Why are spectrum of different atoms different? Or
  atom vs. ion?

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Atomic Sodium
Magnesium (I) ion
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emission
absorbance
fluorescence
Schematic of absorption, emission and
fluorescence by atoms in a flame.
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A. Atomic Emission Spectra

• At room temperature all atoms in a sample are in
  ground state.

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B. Atomic Absorption Spectra

• Atoms are in hot gaseous medium absorb radiation

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B. Atomic Fluorescence Spectra

• Atoms can be made to fluoresce by irradiating the
  flame with an source that contains the
  wavelengths absorbed by the element

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II. Temperature and Atomic Spectra

• Has large effect on number of excited and
  unexcited atomic particles

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Example

• Calculate the ratio of sodium atoms in the 3p
  excited states to the number in the ground state
  at 2500K and 2510K

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III. Atomization

• Converts sample to gaseous atoms or ionized atoms
• Nebulizer

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B. Flame atomization

• In flame atomizer a solution of the sample is
  nebulized by a flow of gaseous oxidant, mixed
  with a gaseous fuel and then carried into a flame
  where atomization occurs.

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C. Flame

• In general

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II. Atomic Absorbance Instrumentation

• A. Radiation Sources

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1. Hollow Cathode Lamp
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IV. Sources of Interferences

1. Spectral Interferences interfering species that
   give spectral lines that overlap with analyte
   lines

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B. Chemical Interference

• Matrix ion may form complex

• Ionization in flame

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V. Atomic Emission

• Inductively coupled plasma

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A. Advantages/Disadvantages of ICP