Absolute calibration of atomic density measurements by laser-induced fluorescence spectroscopy with two-photon excitation

The two-photon resonances of atomic hydrogen (λ = 2 × 205.1 nm), atomic nitrogen (λ = 2 × 206.6 nm) and atomic oxygen (λ = 2 × 225.6 nm) are investigated together with two selected transitions in krypton (λ = 2 × 204.2 nm) and xenon (λ = 2 × 225.5 nm). The natural lifetimes of the excited states, quenching coefficients for the most important collisions partners, and the relevant ratios of the two-photon excitation cross sections are measured. These data can be applied to provide a calibration for two-photon laser-induced fluorescence measurements based on comparisons with spectrally neighbouring noble gas resonances.