Which light source is used in atomic absorption spectrophotometry?

Which light source is used in atomic absorption spectrophotometry?

• A. Hollow-cathode lamp
• B. Xenon arc lamp
• C. Tungsten light
• D. Deuterium lamp

Answer: (A)

In atomic absorption spectrophotometry, the light source must provide photons at the exact wavelengths that the element being measured absorbs. A hollow-cathode lamp delivers this precisely because it is built with a cathode made of the element of interest; when energized, it emits sharp, characteristic emission lines at the element’s specific wavelengths. Those lines pass through the sample, and the amount of light absorbed at those wavelengths correlates with the element’s concentration. Other light sources emit broad or continuum spectra rather than element-specific lines, which reduces selectivity and sensitivity in AAS. For example, a continuum source can complicate measurement of a single atomic transition and isn’t tailored to the element, making hollow-cathode lamps the best choice for this technique.

In atomic absorption spectrophotometry, the light source must provide photons at the exact wavelengths that the element being measured absorbs. A hollow-cathode lamp delivers this precisely because it is built with a cathode made of the element of interest; when energized, it emits sharp, characteristic emission lines at the element’s specific wavelengths. Those lines pass through the sample, and the amount of light absorbed at those wavelengths correlates with the element’s concentration.

Other light sources emit broad or continuum spectra rather than element-specific lines, which reduces selectivity and sensitivity in AAS. For example, a continuum source can complicate measurement of a single atomic transition and isn’t tailored to the element, making hollow-cathode lamps the best choice for this technique.