Atomic Absorption spectroscopy (AAS) works by measuring the amount of light absorbed by gaseous atoms of a specific element in a sample. This absorption is unique to each element and proportional to its concentration in the sample.
Here's a more detailed explanation:
1. Atomization:
The sample is first converted into gaseous, free atoms, either by heating in a flame (flame atomic absorption) or in a graphite furnace (electrothermal atomic absorption).
2. Light Source:
A light source, typically a hollow cathode lamp, emits light at specific wavelengths characteristic of the element being analyzed.
3. Absorption:
As the light passes through the gaseous atoms, they selectively absorb light at certain wavelengths corresponding to their electronic transitions.
4. Measurement:
A detector measures the amount of light transmitted through the sample, and the difference between the initial and transmitted light intensity is a measure of the element's concentration.
5. Quantification:
The amount of light absorbed is directly proportional to the concentration of the element in the sample, allowing for quantification.
In essence, AAS leverages the principle that atoms in the ground state can absorb light at very specific wavelengths, and the amount of light absorbed is a direct indication of how many atoms of that element are present.
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