Electrodes for REMPI spectroscopy in static gases and calculation of REMPI intensities: Application to molecular oxygen

Resonance‐enhanced multiphoton ionization (REMPI) of 16 O 2 X 3 ∑ g − (ν = 0) through (3sσ g )d 1 Π g , (ν = 0) by using (2 + 1) one‐colour photons is reported. This REMPI process, already observed and analysed by other authors at low pressure and low rotational temperature with mass spectrometry detection, is used to test our first detector of ionizations. Experimental difficulties have led to the design of an original arrangement of electrodes to collect electrons at room temperature and 1 Torr pressure of static molecular oxygen. A calculated spectrum is compared with the observed REMPI spectrum. The calculation uses the polarizability tensor and takes into account the competition between ionization and predissociation of the Rydberg state.