Question

What is the principle of absorption spectroscopy?

Answer 1

Hint: Spectroscopic techniques that detect the absorption of radiation as a function of frequency or wavelength owing to its interaction with a material are referred to as absorption spectroscopy. The sample receives energy from the emitting field in the form of photons. The absorption spectrum is a change in the strength of absorption as a function of frequency. Across the electromagnetic spectrum, absorption spectroscopy is used.

Complete answer:
A useful analytical tool for both quantitative and qualitative investigation is the absorption of light by atoms. The premise of atomic absorption spectroscopy (AAS) is that unbound atoms in the ground state may absorb light of a certain wavelength. Each element's absorption is unique; no other elements absorb this wavelength. AAS is a single-element technique for analysing trace metals in biological, metallurgical, pharmaceutical, and atmospheric materials, among others. Only a gasified sample with well-separated individual atoms such as Ag, Al, Au, Fe, and Mg may be used to undertake spectroscopic identification of atomic species.
The hollow cathode lamp is the most popular source for atomic absorption studies. A tungsten anode and a cylindrical cathode are situated in a glass tube filled with an inert gas such as argon. The element to be examined serves as the cathode. The sample must be gasified, which necessitates the use of heat. A flame or a graphite furnace is used to create heat. Graphite furnace AAS can test solutions, slurries, and solid materials, whereas flame AAS can only examine solutions. A nebulizer turns the sample into an aerosol that is delivered into the burner in a flame atomizer. The atomization occurs in a flame that is usually fueled by acetylene and nitrous oxide.
Because it atomizes the sample quickly, an electrothermal atomizer has a high sensitivity. Atomization takes place in a cylindrical graphite furnace with open ends on both ends and a central hole for sample input. Two streams of inert gas are utilised. The exterior stream keeps air out of the furnace, while the interior stream keeps vapours from the sample matrix out of the oven as fast as possible. Argon is the most often utilised gas.

Note:
The method uses a sample's atomic absorption spectra to determine the concentration of certain analytes inside it. It depends on the Beer–Lambert law to establish the relationship between the observed absorbance and the analyte concentration since it needs standards with known analyte content.