Photoacoustic Spectroscopy Combined with a Multipass Circular Cell to Detect Low Concentrations of Ammonia Articles uri icon

publication date

  • June 2025

start page

  • 6727-1

end page

  • 6727-15

issue

  • 12

volume

  • 15

Electronic International Standard Serial Number (EISSN)

  • 2076-3417

abstract

  • Photoacoustic spectroscopy (PAS) has become a valuable technique for trace
    gas detection due to its high sensitivity and potential for miniaturization. This study
    presents the development and evaluation of a near-infrared PAS system using a 1532 nm
    semiconductor laser and a multipass cell (MPC) designed to enhance the optical path
    and thereby improve the detection of ammonia (NH3). The minimum detection limit
    was determined to be 770 ppb, with a normalized noise equivalent absorption (NNEA)
    coefficient of 1.07 × 10−8 Wcm−1 Hz−1/2. While competitive with similar PAS systems,
    these results indicate that mid-infrared technologies still offer superior detection thresholds.
    The findings suggest that while this near-infrared setup may not yet match the sensitivity
    of systems using quantum cascade lasers or QEPAS, it offers notable advantages in terms
    of simplicity, cost, and potential for field deployment. The system"s configuration makes
    it a viable and efficient tool for industrial gas monitoring and real-time environmental
    applications, with future improvements likely to come from transitioning to the midinfrared
    region and advancing laser stabilization and miniaturization techniques.

subjects

  • Aeronautics

keywords

  • ammonia; low concentration detection; multipass circular cell; near infrared; optical spectroscopy; photoacoustic