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In this paper, a non-resonant quartz-enhanced photoacoustic spectroscopy (NR-QEPAS) sensor is reported for the first time, to the best of our knowledge.The non-resonant photoacoustic cell (PAC) serves as the region where the photoacoustic effect occurs.NR-QEPAS offers several advantages, including flexible quartz tuning fork (QTF) positioning, frequencymatching-free operation, and simplified optical alignment.A self-designed T-head QTF was utilized as an acoustic wave transducer.The sound pressure characteristics of the non-resonant PAC were simulated using the finite element method.A near-infrared distributed feedback (DFB) diode laser with a wavelength of 1650.96nm was selected as the excitation source.Methane (CH 4 ) was chosen as the target gas to validate the designed sensor's performance.The experimental results showed that the designed non-resonant PAC worked in the plane wave state, and the sound pressure in the cavity was nearly uniform.The minimum detection limit (MDL) of the designed NR-QEPAS sensor for CH 4 detection could be 1.09 ppm (1 ppm = 10 -6 ) when the average time was 760 s.
Yang et al. (Wed,) studied this question.