Hydrogen Sulfide Detection in the Midinfrared Using a 3D-Printed Resonant Gas Cell

Abstract

A fast and reliable photoacoustic (PA) sensor for trace gas detection is reported. The sensor is based on a 3D-printed resonant cell in combination with a continuous wave mode-hop-free external cavity quantum cascade laser to rapidly acquire gas absorption data in the midinfrared range. The cell is designed so as to minimize the window PA background at a selected acoustic resonance. The goal is a resonant PA cell capable of detecting the traces of gases using wavelength modulation of the laser source and second harmonic detection. The versatility and enhancement of the limit of detection at sub-ppm levels are investigated by monitoring specific lines of hydrogen sulfide (H 2 S). The noise-equivalent absorption normalized to laser-beam power and detection bandwidth is 1 07 × 10 -8 W cm -1 Hz -1/2 for H 2 S targeting the absorption line at 1247.2 cm −1 . These properties make the sensor suitable for various practical sensors for water quality applications.

Sub-ppm-Level Ammonia Detection Using Photoacoustic Spectroscopy with an Optical Microphone Based on a Phase Interferometer

“…It was terminated with two cylindrical buffer volumes, which are considered acoustic filters where the gas inlet/outlet connectors and the optical windows were installed. It is based on a previous design [19] with two main modifications; the first is the building material, it was made of aluminium, and the other was including a second hole (3-mm diameter) in the centre of the resonator for installing a diaphragm.…”

Photoacoustic-Based Gas Sensing: A Review

“…Hydrogel Sulfide (H 2 S) QCL [136] CO 2 Laser [130] LD [137][138][139] Water (H 2 O) QCL [125,140] LD [133,134,141] LED [142] Acetylene (C 2 H 2 ) CO 2 Laser [143] LD [87,144,145] Methane (CH 4 ) QCL [146][147][148] LD [87,133,146,149] OPO [150] Ozone (O 3 ) QCL [151] quadrupled Nd:YAG [152] Hydrogen Chloride (HCl) LD [149,153] Ethylene (C 2 H 4 ) CO 2 Laser [98] 3.2.3. Quartz-Enhanced and Cantilever Photoacoustic Absorption Spectroscopy Low-cost reliable MEMS devices often allow for advances in miniaturization and improvement of performances in originally unforeseen applications.…”

H2S quartz-enhanced photoacoustic spectroscopy sensor employing a liquid-nitrogen-cooled THz quantum cascade laser operating in pulsed mode

“…Standard photoacoustic and QEPAS sensors for in situ and real-time detection of multiple hydrocarbons in near- and mid-IR were already demonstrated, as well as H 2 S sensors employing diode lasers in the near-IR [ 26 ] and quantum cascade lasers (QCLs) in the mid-IR [ 23 , 24 ]. Helman et al were able to detect H 2 S with a sensitivity of 492 ppb at 1 s of integration time in off-beam configuration [ 25 ].…”