laser multiphoton ionisation spectroscopy resonance enhanced multiphoton ionisation spectroscopy REMPI resonance-enhanced multiphoton ionisation spectroscopy REMPI spectroscopy resonance enhanced multiphoton ionization spectrometry CHMO:0000466 resonance-enhanced multiphoton ionisation spectrometry resonance enhanced multiphoton ionisation spectrometry resonance-enhanced multiphoton ionization spectroscopy resonance-enhanced multiphoton ionization spectrometry Spectroscopy where a sample is illuminated with resonant laser light (using a laser which is tuned to match an electronic transitions within the sample) and photoexcitation (by the absorption of two or more photons) is used to promote an atom or molecule above its ionisation potential to create an ion. REMPI spectrometry