High Resolution Molecular Spectroscopy with Lasers

Several sensitive detection techniques, such as excitation spectroscopy or resonant two-photon ionization spectroscopy are applied to laser spectroscopy with sub-Doppler resolution in collimated molecular beams. Due to internal cooling during the adiabatic expansion in supersonic beams rotational temperatures below 10 K can be reached which results in a drastic simplification of otherwise complex molecular spectra.