Evaluation of absolute optical oscillator strengths for transitions from the A-state to the np Rydberg series in NO

We describe a method for calibrating oscillator strengths for transitions of a molecule from the A-state to the Rydberg states with the absolute scale for the transition from the A-state to the ground state. Two-colour resonant four-wave mixing spectroscopy has been used to record the spectra for the NO transitions from the A2Σ+ (υ′=0) state to both the vibrationally excited X2Π3/2 (υ″=8) electronic ground state and to the high Rydberg series at the same time. By comparison with the normalised relative signal intensities, absolute oscillator strengths for the transitions from the A-state to the np2Π+ Rydberg series have been evaluated based on the knowledge of this parameter for the NO γ band system.