Resonance-Ionization Spectroscopy (RIS)
Introduction
Resonance-ionization spectroscopy (RIS) is a spectroscopic
method that uses resonant laser excitation to promote an atom or molecule
above its ionization potential to create an ion. The ions are detected
as a current by a biased collector or by a mass spectrometer. RIS is useful
to study the electronic structure of atoms or molecules and to make quantitative
measurements of analyte concentrations. For more information see the document
on RIMS.
Laser-enhanced ionization
Laser-enhanced ionization (LEI) ionizes atoms in a flame. It relies on
resonant laser excitation of an atom to a higher electronic excited state.
The excited atom is then ionized by collisions in the flame. The ions are
collected by biased wires or plates in or near the flame. The LEI method
produces lower limits of detection for several elements.