Atomic Emission Sources
- Page ID
- 75257
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Remember that the analyte must be converted to atoms, and then an electron in the atom must be promoted to an excited state so the electron can go to a lower energy level/emission occurs. The percentage of atoms in the excited state is controlled by factors such as temperature, available orbitals, and the energy of the transition. You can see here what can happen to analyte in an emission source. The theoretical ratio or distribution can be calculated by the Boltzmann distribution equation:
\[ \dfrac{N_j}{N_o} = \dfrac{P_j}{P_o} e^{-\Delta E/kT} \nonumber \]
- Nj = # of atoms in the excited state
- N0 = # of atoms in the ground state
- Pj = statistical factor (related to the number orbitals) for electrons in the excited state
- P0 = statistical factor (related to the number orbitals) for electrons in the ground state
- ΔE = energy transition
- k = Boltzmann's constant
- T = temperature (Kelvin)
Dependent on the element and transition, the ratio of atoms can be calculated! As a guide, the relative temperatures for several atomizers is listed below:
| Types of Atomizers | Typical Atomizer Temperature (oC) |
|---|---|
| Flame | 1700-3150 |
| Inductively Coupled Plasma (ICP) | 8000-10000 |
| Direct Current Plasma (DCP) | 4000-6000 |
| Microwave Induced Plasma (MIP) | 2000-3000 |
| Glow discharge plasma | Nonthermal |
| Electric arc | 4000-5000 |
| Electric spark | ~40,000 (?) |