Linewidths and line intensity measurements in the weak 3A2(000) ← 1A1(000) band of ozone by pulsed cavity ringdown spectroscopy

Abstract

Pulsed cavity ringdown spectroscopy in the near‐infrared spectral range was employed to measure linewidths of the 3A2(000) ← 1A1(000) band of ozone in direct comparison with intracavity laser absorption spectroscopy. It is demonstrated that also for a small ratio, V, which is the ratio of the absorption linewidth and the laser bandwidth, correct linewidths can be determined from a forward modeling of the experimental line profiles, taking explicitly into account the laser bandwidth and the cavity modes. The obtained linewidths have been compared with those measured by intracavity laser absorption spectroscopy and found to agree quantitatively within experimental error. Linewidths as a function of pressure have been analyzed to obtain pressure‐broadening coefficients and the effective linewidth at zero pressure, which is a measure for the excited state lifetimes of the ozone in the excited triplet states. The observed linewidths are a direct observable for the intramolecular dynamics in the low‐lying excited 3A2 triplet state of ozone. In any case, the observed lifetimes for the excited 3A2(000) state in the range between 20 and 130 picoseconds (ps) rule out metastability of this state. Beyond linewidth measurements we have also refined the spectroscopic parameters of this electronically excited state and determined the integrated absorption of the corresponding 3A2(000) ← 1A1(000) transition.