What is the light source used in atomic absorption spectrophotometry?

In atomic absorption spectrophotometry (AAS), the light source most commonly used is the hollow cathode lamp. This instrument contains a cathode made of the element that is to be analyzed and operates by generating light through the excitation of atoms within the cathode. When a current passes through the inert gas (usually neon or argon) in the lamp, it ionizes the gas, and the excited ions collide with the cathode, causing the cathode material to emit characteristic wavelengths of light as it returns to its ground state.

The hollow cathode lamp is specifically designed for this purpose and provides a sharp and specific spectral output that corresponds directly to the elemental analysis being performed. Its design allows for optimal intensity of the light emitted, making it highly efficient for measuring absorbance of specific elements in a sample.

Other light sources mentioned are not suitable for atomic absorption spectrophotometry. For instance, tungsten lamps are typically used in visible light applications and are not specific to any element, whereas deuterium lamps are primarily used in UV spectrophotometry. Mercury vapor lamps are generally used for fluorescence applications and are also not tailored for AAS. The specificity and functionality of the hollow cathode lamp make it the ideal choice for accurate atomic absorption