Monitoring of ethylene by a pulsed quantum cascade laser

Abstract

We report on the development and performance of a gas sensor based on a quantum cascade laser operating at a wavelength of approximately 10 microns to measure ethylene (C2H4) concentrations by use of a rotational component of the fundamental nu 7 band. The laser is thermoelectrically cooled and operates in a pulsed mode. The influence of pulse-to-pulse fluctuations is minimized by use of a reference beam and a single detector with time discriminating electronics. Gas absorption is recorded in a 100-m optical path-length astigmatic Herriott cell. With a 10-kHz pulse repetition rate and an 80-s total acquisition time, a noise equivalent sensitivity of 30 parts per billion has been demonstrated. The sensor has been applied to monitor C2H4 in vehicle exhaust as well as in air collected in a high-traffic urban tunnel.

CO2 laser photoacoustic detection of ethylene emitted by diesel engines used in urban public transports

“…Campos dos Goytacazes has a fleet composed by more than 1000 old urban buses powered by diesel oil [4,5], with more than 10 years of use and without filters. As a consequence, these vehicles produce large amounts of pollutant gases, such as the volatile organic compounds (VOCs), with ethylene among them [6][7][8].…”

Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection

“…Weidmann et al [13] reported the development of a gas sensor based on long-path absorption and a quantum cascade laser for the detection of ethylene (C 2 H 4 ). The laser, operated in a pulsed mode at a wavelength of ∼10 μm, was thermoelectrically cooled.…”

The quantum cascade laser: A versatile high-power semiconductor laser for mid-infrared applications

“…Other QCL spectroscopy studies include ammonia, methane, CO 2 , and ethylene [41], to name just a few. Recently, a trace gas sensor based on quartzenhanced photoacoustic spectroscopy with a QCL operating at 4.55 m was developed for the detection of N 2 O and CO and was found to have a sensitivity of 4 ppb for N 2 O [23].…”