Work

Ppb-Level Self-Calibrating Ozone Detection Using a T-Type Multipass Enhanced Photoacoustic Sensor with a 9.46 μm Quantum Cascade Laser

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide A sensitive, real-time, and accurate ozone (O 3 ) sensor system is developed based on the combination of multipass enhanced photoacoustic (MPPA) and direct multipass absorption spectroscopy with a mid-infrared quantum cascade laser (QCL). The QCL with an emission wavelength of 9.46 μm was used to probe the O 3 absorption lines without interference from the absorption of water and carbon dioxide in the flowing mixtures. The MPPA sensor was constructed with a T-type cell composed of a vertical cylinder and a horizontal cavity which were designed as an acoustic resonator and for multipass absorption enhancement, respectively. By periodically on–off switching the modulation of the laser wavelength, rapidly switched measurements of direct absorption and PA spectra can be achieved for real-time and accurate calibrations of the second harmonic (2f) PA signals with the direct absorbance spectra of O 3 . Moreover, a detection limit of O 3 of 6 ppb at an average time of 300 s was achieved, and a short sensor response time of 16 s was also obtained in the flow mixtures with a flow rate of 50 sccm. This work provides a reliable method for O 3 detection with capabilities of parts-per-billion-level sensitivity and on-site real-time concentration calibration, thus holding promise for in situ ozone monitoring under various environments.

Source: Analytical Chemistry

DOI: 10.1021/acs.analchem.4c04999

Authors: Yu-Xuan Wu, Pei-Ling Luo

Institutions: National Taiwan Normal University, Institute of Atomic and Molecular Sciences, Academia Sinica, Academia Sinica

Language: English

Topic: Spectroscopy and Laser Applications

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funder: National Science and Technology Council