from W. Demtröder “Molecular Physics”

IR-UV Double Resonance X, v=0 el. excited state X, v=1 fluorescence Technique: Fix UV laser, scan IR laser, measure fluorescence signal as function of IR frequency to obtain vibrational spectrum of ground state Advantage: “Action spectroscopy” – probe generation of fluorescence photons, background-free, more sensitive than IR absorption

Resonant Two-Photon Ionization (R2PI) |0> |k> ionization continuum Technique: Scan laser, measure ion signal as function of laser frequency to obtain spectrum of excited state Advantages: Mass spectroscopic detection is very sensitive (much better than UV/vis absorption spectroscopy) “Action spectroscopy” – probe generation of ion, background-free

from W. Demtröder “Molecular Physics”