Ozone Detection via Deep-Ultraviolet Cavity-Enhanced Absorption Spectroscopy with a Laser Driven Light Source

We present a novel sensing approach for ambient ozone detection based on deep-ultraviolet (DUV) cavity-enhanced absorption spectroscopy (CEAS) using a laser driven light source (LDLS). The LDLS has broadband spectral output which, with filtering, provides illumination between similar to 230-280 nm. The lamp light is coupled to an optical cavity formed from a pair of high-reflectivity (R similar to 0.99) mirrors to yield an effective path length of similar to 58 m. The CEAS signal is detected with a UV spectrometer at the cavity output and spectra are fitted to yield the ozone concentration. We find a good sensor accuracy of <similar to 2% error and sensor precision of similar to 0.3 ppb (for measurement times of similar to 5 s). The small-volume (<similar to 0.1 L) optical cavity is amenable to a fast response with a sensor (10-90%) response time of similar to 0.5 s. Demonstrative sampling of outdoor air is also shown with favorable agreement against a reference analyzer. The DUV-CEAS sensor compares favorably against other ozone detection instruments and may be particularly useful for ground-level sampling including that from mobile platforms. The sensor development work presented here can also inform of the possibilities of DUV-CEAS with LDLSs for the detection of other ambient species including volatile organic compounds.