From W. Demtröder “Molecular Physics”

From W. Demtröder “Molecular Physics”

from Herzberg: Molecular Spectra & Molecular Structure

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>

ionizationcontinuum

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 ions, background-free