Atomic spectroscopy studies the emission, absorption and scattering associated with the energy levels of chemical atoms and ions. The positions of spectral lines identify differences of energy, while their strengths and polarization also depend on populations and selection rules.
A dilute-gas discharge can excite chemical atoms; a spectrometer then separates the emitted light by wavelength. Comparing the resulting lines with an independently calibrated reference can identify an element or reveal an isotope shift. Changing a magnetic field tests Zeeman splitting, and improving energy resolution can reveal fine structure. Different experimental changes therefore isolate different pieces of the atomic model.
The wavelength-dependent distribution of sunlight, including absorption lines used to investigate the solar atmosphere.
An isotope shift is a difference between corresponding atomic transition frequencies in different isotopes. One contribution comes from nuclear mass, through recoil and electron correlations; another comes from the changing nuclear charge distribution. For a specified transition, the leading finite-size contribution is often written , with an electronic factor . Extracting changes of nuclear charge radius therefore requires separating mass and finite-size contributions rather than identifying the entire shift with radius.
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Atomic spectroscopy is a set of analytical techniques used to determine the elemental composition of substances by measuring the light emitted or absorbed by atoms. The primary principle behind atomic spectroscopy is that atoms have distinct energy levels, and when they transition between these levels, they emit or absorb electromagnetic radiation at specific wavelengths. This unique spectral information can be used to identify and quantify elements within a sample.