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Flame Excitation Source
Introduction
A flame provides a high-temperature source for desolvating
and vaporizing a sample to obtain free atoms for spectroscopic
analysis. In atomic absorption spectroscopy ground state atoms
are desired. For atomic emission spectroscopy the flame must also
excite the atoms to higher energy levels. The table lists temperatures
that can be achieved in some commonly used flames.
Temperatures of some common flames
| Fuel |
Oxidant |
Temperature (K) |
| H2 |
Air |
2000-2100 |
| C2H2 |
Air |
2100-2400 |
| H2 |
O2 |
2600-2700 |
| C2H2 |
N2O |
2600-2800 |
Introduction
The figure shows a total consumption burner in which
the sample solution is directly aspirated into the flame. This
flame design is common for atomic emission spectroscopy. All desolvation,
atomization, and excitation occurs in the flame. Other flame designs
nebulize the sample and premix it with the fuel and oxidant before
it reaches the burner. Atomic-absorption instruments almost always
use a nebulizer and also use a slot burner to increase the path
length for the sample absorption. 