Atomic absorption spectroscopy sounds complicated, and while, in practice, it is, the basic principles and methods can be easily understood by anyone with a basic understanding of how atoms work. Below is a look at the key principles that an atomic absorption spectrophotometer uses and how they are apllied to analyse a sample.
First, it is important to understand how atoms, and more specifically, the electrons within the atom work.
Electrons move around the nucleus of an atom at specific intervals, called valances. The valance that they move on is determined by the amount of energy they have. Keep in mind that this number is always exactly the same, as too little energy will not cause a partial jump, and any extra energy will be rejected.
Since each atom's specific behavioural patterns and the amount of energy is required to make its electrons jump from one valance to another, adding a specific amount of energy at a specific frequency and measuring the amount that is absorbed will give people information about the exact amount that a target substance or sample contains.
In addition, as long as the energy level and frequency is adjustable, a spectrophotometer can be used to determine the presence and percentage of any element in a given sample.
Applying the above principles is as simple as taking a sample whose chemical makeup is to be tested and burning it, thus separating it into its component atoms. (Note this requires a lot of heat if the analysis is to be accurate.)
When the sample is burning, a light (energy) of a known wavelength and magnitude, specific to the element being tested for is shined through it. By measuring the amount of light that passes through the sample, and, more specifically, the amount of light energy that the sample absorbes, the amount of the given element that exists in the sample can be determined with extreme accuracy .
Changing the light to one of a different wavelength allows another element to be tested for, and, if repeated several times with different lights, can yield a very accurate and complete analysis of any given sample.
Several different varieties of atomic absorption spectrophotometers exist, but they all operate on these same basic principles.