Atomic Emission Spectroscopy
Atomic Emission Spectroscopy
Dr M. Al-Harahsheh
Comparison: Flame and
Plasma atomization methods
•
Excitation and atomization for absorption:
– Traditionally based on
•
•
•
•
•
•
1)
2)
3)
4)
5)
6)
7)
8)
flame
Electrothermal
arc and spark & Plasma find important application
ICP is the most important
but excitation for emission spectrometry offers increased atomization/excitation
Lower inter-element interference due to high T emission from multiple species simultaneously under a set of excitation conditions spectra for many elements can be recorded smultaneusly wider range of elements
Possibility of determination of low concentration levels of high stability oxide forming elements (B, P, W, U, Zr, Nb)
Possibility to determine nonmetals like (Cl, Br, I, S), but poor detection limit wide dynamic range
Suitability of automated analysis
Dr M. Al-Harahsheh
Comparison Flame and Plasma atomization methods1
• AAS:
– Less expensive equipment
– Lower operating cost
– Somewhat greater precision!!
– Require less operator skills
Dr M. Al-Harahsheh
Advantages of Plasma Source
• Ion emission lines are significant and usable
(e.g., Ca+, Ca2+)
• Background emission is low in observation region (Ar, OH, NO, NH, CN lines)
• Surprisingly, excessive ionization is low, due to excess e– in plasma
• Oxide formation is nil
• Low level of self-absorption due to high proportion of excited atoms→response is linear over many orders of magnitude
Dr M. Al-Harahsheh
Arc and Spark Atomization
• They were used before ICP but they were later replaced by ICP because of the:
– Instability which necessitates to integrate over 20 s to get reproducible data
• Sample excitation occurs in a gap between two electrodes. Passage of electricity between electrodes through the gap provide sufficient energy for atomization the sample
Dr M. Al-Harahsheh
Plasma Emission Spectroscopy
Plasma: an electrical conducting
Dr M. Al-Harahsheh
Comparison: Flame and
Plasma atomization methods
•
Excitation and atomization for absorption:
– Traditionally based on
•
•
•
•
•
•
1)
2)
3)
4)
5)
6)
7)
8)
flame
Electrothermal
arc and spark & Plasma find important application
ICP is the most important
but excitation for emission spectrometry offers increased atomization/excitation
Lower inter-element interference due to high T emission from multiple species simultaneously under a set of excitation conditions spectra for many elements can be recorded smultaneusly wider range of elements
Possibility of determination of low concentration levels of high stability oxide forming elements (B, P, W, U, Zr, Nb)
Possibility to determine nonmetals like (Cl, Br, I, S), but poor detection limit wide dynamic range
Suitability of automated analysis
Dr M. Al-Harahsheh
Comparison Flame and Plasma atomization methods1
• AAS:
– Less expensive equipment
– Lower operating cost
– Somewhat greater precision!!
– Require less operator skills
Dr M. Al-Harahsheh
Advantages of Plasma Source
• Ion emission lines are significant and usable
(e.g., Ca+, Ca2+)
• Background emission is low in observation region (Ar, OH, NO, NH, CN lines)
• Surprisingly, excessive ionization is low, due to excess e– in plasma
• Oxide formation is nil
• Low level of self-absorption due to high proportion of excited atoms→response is linear over many orders of magnitude
Dr M. Al-Harahsheh
Arc and Spark Atomization
• They were used before ICP but they were later replaced by ICP because of the:
– Instability which necessitates to integrate over 20 s to get reproducible data
• Sample excitation occurs in a gap between two electrodes. Passage of electricity between electrodes through the gap provide sufficient energy for atomization the sample
Dr M. Al-Harahsheh
Plasma Emission Spectroscopy
Plasma: an electrical conducting