A Rollar‐Type Resonant Photoacoustic Spectroscopy for Trace Gas Detection

ABSTRACT This paper presents a miniature Rollar‐type resonant photoacoustic cell (RRPAC), consisting of two cylindrical resonant cavities and a buffer chamber. The finite element analysis of the acoustic field distributions for the RRPAC and T‐type resonant photoacoustic cell (TRPAC) is utilized, demonstrating that RRPAC can produce a greater photoacoustic signal than the conventional TRPAC. A high sensitivity trace C 2 H 2 photoacoustic spectroscopy (PAS) system is successfully developed by combining a cantilever beam‐based acoustic sensor as the acoustic sensing unit and a high‐speed spectrometer as the demodulation unit with the RRPAC. The experimental results indicate that the 2f signal of the RRPAC at the first‐order resonance mode is approximately 1.5 times of the TRPAC with the same C 2 H 2 concentration. The gas detection limit of the RRPAC PAS system for C 2 H 2 is 40.7 ppb at an averaging time of 100 s. In comparison with the conventional TRPAC, the RRPAC exhibits higher sensitivity, thus providing a novel solution for the advancement of the PAS system.