Quantitative spectroscopy of spin-rovibronic transitions broadened by predissociation in the 3A2(010)-X1A1(000) Wulf band of ozone near 1 µm

The weak ozone spectrum is recorded by cavity ring down spectroscopy in the region of the Wulf band of ozone near 1 µm. The line profile of six regular sequences of mostly resolved lines belonging to the singlet-triplet 3 A 2 (010)-X 1 A 1 (000) band are studied between 9760 and 9915 cm -1 . The upper states of the 47 targeted transitions are affected by predissociation processes due to the mixing of the 3 A 2 upper triplet electronic state with the near lying states of the X 1 A 1 grand state, by spin-orbit coupling. A series of four recordings for ozone pressures ranging between 10 and 40 Torr allows for (i) disentangling the pressure broadening (proportional to pressure) and the (dominant) predissociation broadening (independent on pressure) (ii) determining accurate values of the absolute line intensities, on the order of 10 -24 cm/molecule for the strongest transitions. The retrieved predissociation widths range between 0.03 and 0.37 cm -1 corresponding to life times of 87 and 7 ps, respectively. The magnitude of these values and their strong dependence on rotational quantum numbers are discussed.