Measurements of Cavity Ringdown Spectroscopy of Acetone in the Ultraviolet and Near-Infrared Spectral Regions: Potential for Development of a Breath Analyzer

We report a study on the cavity ringdown spectroscopy of acetone in both the ultraviolet (UV) and the near-infrared (NIR) spectral regions to explore the potential for development of a breath analyzer for disease diagnostics. The ringdown spectrum of acetone in the UV (282.4–285.0 nm) region is recorded and the spectrum is in good agreement with those obtained by other spectral techniques reported in the literature. The absorption cross-section of the C–H stretching overtone of acetone in the NIR (1632.7–1672.2 nm) is reported for the first time and the maximum absorption cross-section located at 1666.7 nm is 1.2 × 10−21 cm2. A novel, compact, atmospheric cavity with a cavity length of 10 cm has been constructed and implemented to investigate the technical feasibility of the potential instrument size, optical configuration, and detection sensitivity. The detection limit of such a mini cavity employing ringdown mirrors of reflectivity of 99.85% at 266 nm, where acetone has the strongest absorption, is ∼1.5 ppmv based on the standard 3σ criteria. No real breath gas samples are used in the present study. Discussions on the detection sensitivity and background spectral interferences for the instrument development are presented. This study demonstrates the potential of developing a portable, sensitive breath analyzer for medical applications using the cavity ringdown spectral technique.