Highly sensitive photoacoustic acetylene detection based on differential photoacoustic cell with retro-reflection-cavity

In this paper, a highly sensitive photoacoustic spectroscopy (PAS) sensor based on retro-reflection-cavityenhanced differential photoacoustic cell (DPAC) is demonstrated for the first time. Acetylene (C2H2) was selected as the analyte. The DPAC was designed to effectively suppress noise and increase signal level. The retroreflection-cavity consisted of two right-angle prisms was designed to reflect the incident light to realize four passes. The photoacoustic response of the DPAC was simulated and investigated based on the finite element method. Wavelength modulation and second harmonic demodulation technologies were applied for sensitive trace gas detection. The first-order resonant frequency of the DPAC was found to be 1310 Hz. The differential characteristics were investigated and the 2f signal amplitude for this C2H2-PAS sensor based on retro-reflectioncavity-enhanced DPAC had a 3.55 times improvement compared to the system without the retro-reflectioncavity. An Allan deviation analysis was performed to investigate the long-term stability of the system. The minimum detection limit (MDL) was measured to be 15.81 ppb with an integration time of 100 s

Automated summary

A highly sensitive photoacoustic spectroscopy sensor based on retro-reflection-cavity-enhanced differential photoacoustic cell (DPAC) is demonstrated for the first time in this paper. Acetylene was chosen as the analyte and the DPAC was designed to suppress noise and increase signal level. The retro-reflection-cavity, consisting of two right-angle prisms, was utilized to achieve four passes of the incident light. Wavelength modulation and second harmonic demodulation techniques were employed for sensitive trace gas detection. The DPAC showed a 3.55 times improvement in the 2f signal amplitude compared to the system without the retro-reflection-cavity. Allan deviation analysis was conducted to evaluate the long-term stability of the system and the minimum detection limit (MDL) was measured to be 15.81 ppb with an integration time of 100 s.