State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy , Shanxi University , Taiyuan 030006 , P. R. China.
Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan 030006 , P. R. China.
ACS Sens. 2020 Feb 28;5(2):549-556. doi: 10.1021/acssensors.9b02448. Epub 2020 Jan 24.
A sensitive photoacoustic sensor system for the detection of ppb-level sulfur dioxide (SO) was developed by the use of a continuous-wave room-temperature, high-power quantum cascade laser (QCL) with an external diffraction grating cavity geometry. The excitation wavelength of the QCL was set to 7.41 μm for the strongest SO absorption line strength. A custom-made differential photoacoustic cell (PAC) with two identical resonators was designed to allow a gas flow rate up to 1200 sccm. A qualitative theoretical model was employed in order to understand the dynamic adsorption and desorption processes of SO in the PAC walls. A 1σ detection limit of 2.45 ppb, corresponding to a normalized noise equivalent absorption value of 3.32 × 10 cm W/Hz, was achieved after measures for suppressing the absorption-desorption effect were taken.
采用连续波室温、高功率量子级联激光器（QCL）结合外腔光栅结构，开发了一种用于检测 ppb 级二氧化硫（SO）的灵敏光声传感器系统。QCL 的激发波长设定为 7.41μm，这是 SO 最强吸收线强度的波长。设计了一个定制的差分光声池（PAC），带有两个相同的谐振器，允许气体流速高达 1200sccm。采用定性理论模型来理解 SO 在 PAC 壁中的动态吸附和解吸过程。在采取抑制吸收-解吸效应的措施后，实现了 2.45ppb 的 1σ检测限，对应于归一化噪声等效吸收值 3.32×10^-6cm W/Hz。
