Emissionspektroskopi

Emissionspektroskopi, or emission spectroscopy in English, is a spectroscopic technique for determining the elemental composition of a sample by analyzing the light emitted by excited species. When atoms or ions in a sample are energized—by flame, electrothermal sources, inductively coupled plasma, or laser ablation—electrons are promoted to higher energy levels. The subsequent return to lower levels emits photons at characteristic wavelengths, producing an emission spectrum that serves as a molecular fingerprint for the elements present.

Instruments detect and quantify light using a dispersion element (grating or prism) and a detector such as a photomultiplier tube or a charge-coupled device. The emitted light intensity at selected wavelengths is related to element concentration through calibration against standards.

Common variants include flame emission spectroscopy (for certain metal ions), electrothermal emission (such as graphite furnace emission), and inductively coupled plasma optical emission spectroscopy (ICP-OES), which allows simultaneous multi-element analysis with high sensitivity. Other forms include laser-induced breakdown spectroscopy (LIBS).

Applications span environmental monitoring (trace metals in water), geology and mining, metallurgy, agriculture, and clinical chemistry. Strengths include rapid multielement analysis, wide dynamic range, and relatively low equipment costs for some setups. Limitations involve spectral line overlaps (interferences), matrix effects, limited sensitivity for some elements compared with mass spectrometric methods, and the need for careful calibration and background correction.