Tu Tan

TL;DR: In this article, high-sensitive detection of atmospheric methane (CH4) was performed by long optical pathlength absorption spectroscopy based on a novel compact dense-pattern multipass cell (DP-MPC) in conjunction with a fiber-coupled distributed feedback diode laser operating at 1.653μm.

TL;DR: Broadband off-beam quartz-enhanced photoacoustic spectroscopy (BB-OB-QEPAS) to trace NO2 detection using a broadband blue laser diode centered at 450 nm was applied for the first time.

TL;DR: A gas sensor based on off-beam quartz enhanced photoacoustic spectroscopy was developed and optimized, and the outer tube shape is modified for enhancing the trace gas detection sensitivity.

TL;DR: The present work shows that the use of T-mR in QEPAS based sensor can improve the detection sensitivity by a factor of up to ~30, compared with that using only a bare QTF.

Abstract: Based on a new spectrophone configuration using a single microresonator (mR) in “on beam” quartz-enhanced photoacoustic spectroscopy (QEPAS), referred to “half on beam QEPAS”, a classical acoustic model originated from “orifice ended tube” was introduced to model and optimize the mR geometrical parameters. The calculated optimum mR parameters were in good agreement with the experimental results obtained in “half on beam” as well as conventional “on beam” QEPAS approaches through monitoring of atmospheric H2O vapor absorption. In addition, spectrophone performances of different QEPAS configurations (off beam, on beam and half on beam) were compared in terms of signal-to-noise ratio (SNR) gain.