Download Atomic Spectroscopy

Chapter 8 and 9
(and a little 10)
Atomic Spectroscopy
Instrumental Analysis
Spring 2011
I. Optical Atomic Spectra
• Again, these are going to be line spectra
• Why are spectrum of different atoms
different? Or atom vs. ion?
Atomic Sodium
Magnesium (I) ion
emission
absorbance
fluorescence
Schematic of absorption, emission and fluorescence by atoms in a flame.
A. Atomic Emission Spectra
• At room temperature all atoms in a sample
are in ground state.
B. Atomic Absorption Spectra
• Atoms are in hot gaseous medium absorb
radiation
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
II. Temperature and Atomic
Spectra
• Has large effect on number of excited and
unexcited atomic particles
Example
• Calculate the ratio of sodium atoms in the
3p excited states to the number in the
ground state at 2500K and 2510K
III. Atomization
• Converts sample to gaseous atoms or
ionized atoms
A. Nebulizer
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.
C. Flame
• In general:
II. Atomic Absorbance
Instrumentation
A. Radiation Sources
1. Hollow Cathode Lamp
IV. Sources of Interferences
A. Spectral Interferences: interfering species
that give spectral lines that overlap with
analyte lines
B. Chemical Interference
• Matrix ion may form
complex
• Ionization in flame
V. Atomic Emission
• Inductively coupled
plasma
A. Advantages/Disadvantages of ICP