Atomic Fluorescence Spectroscopy
Definition and meaning of Atomic Fluorescence Spectroscopy in chemistry.
Atomic fluorescence spectroscopy is an analytical technique that detects elements by measuring fluorescence emitted from excited atoms. The technique uses light to excite ground-state atoms to higher energy levels, then measures the characteristic fluorescence radiation emitted as they relax back to their original state.
In more detail
AFS employs a light source (typically a hollow cathode lamp) to excite atoms in a vaporized sample. As excited atoms return to their ground state, they emit fluorescence radiation at characteristic wavelengths specific to each element. A monochromator isolates this fluorescence, and a detector measures its intensity, which correlates directly with element concentration. AFS offers excellent sensitivity and selectivity, enabling both qualitative identification and quantitative analysis of trace elements in environmental, pharmaceutical, and research samples.
Key facts
| Field | Analytical Chemistry |
|---|---|
| Detection range | Parts per trillion (ppt) to parts per million (ppm) depending on element and conditions |
| Primary advantage | Higher sensitivity and lower detection limits than atomic absorption spectroscopy for certain elements |
| Sample requirement | Atoms must be vaporized (from liquid, gas, or solid samples) to enter the excitation zone |
Detecting mercury vapor in air and water samples is a classic AFS application, where it provides superior sensitivity and specificity compared to atomic absorption spectroscopy, enabling measurement of concentrations as low as parts per trillion (ppt).
Frequently asked questions
How does atomic fluorescence spectroscopy differ from atomic absorption spectroscopy?
While AAS measures light absorbed by ground-state atoms, AFS measures light emitted by excited atoms returning to their ground state. AFS typically offers superior sensitivity and lower detection limits for many elements.
What are common light sources used in AFS?
Hollow cathode lamps are the most common, though xenon arc lamps and other continuous sources may be used. The light source must produce wavelengths capable of exciting the target element.