Ammonia detection by using quantum-cascade laser photoacoustic spectroscopy

Abstract

A pulsed quantum-cascade distributed-feedback laser, temperature tunable from -41 degrees C to +31.6 degrees C, and a resonant differential photoacoustic detector are used to measure trace-gas concentrations to as low as 66 parts per 10(9) by volume (ppbv) ammonia at a low laser power of 2 mW. Good agreement between the experimental spectrum and the simulated HITRAN spectrum of NH3 is found in the spectral range between 1046 and 1052 cm(-1). A detection limit of 30 ppbv ammonia at a signal-to-noise ratio of 1 was obtained with the quantum-cascade laser (QCL) photoacoustic (PA) setup. Concentration changes of approximately 50 ppbv were detectable with this compact and versatile QCL-based PA detection system. The performance of the PA detector, characterized by the product of the incident laser power and the minimum detectable absorption coefficient, was 4.7 x 10-9 W cm(-1).

Miniaturized Optical Sensors for Medical Diagnostics

“…This modulated pressure change generates an acoustic wave, which may be detected by a microphone(s) or by a quartz tuning fork(s) without the need for an optical detector [42]. There have been several reports about achieving ultralow detection levels of analytes in air at the parts-per-billion (ppb) to parts-per-trillion (ppt) concentrations using this scheme [53][54][55][56].…”

“…For example, QCL-PAS sensing systems were able to detect ammonia, a biomarker for asthma, to levels of 66 ppb [54]. The introduction of a quartztuning-fork-enhanced PAS system has considerably increased the sensitivity, and the degree of miniaturization for such devices [57].…”

Detection of Ethylene Emitted by Diesel-biodiesel Engine Using CO2 Laser Photoacoustic Sensors

“…Angelmahr, M., Miklos, A., & Hess, P. (2006). Photoacoustic Spectroscopy of formaldehyde with tunable laser…”

“…This technique is widely used for the detection of several gases in the concentration range of ppbv (Killinger & Mooradian, 1988;Measures, 1988;Sigrist, 1994;Miklos et al 2001;Schramm et al, 2003;Sthel et al, 2005;Angelmahr, Miklos, & Hess, 2006;Filho et al, 2006;Cristescu, Persijn, Hekkert, & Harren, 2008;Sigrist et al, 2008;Berrou, Raybaut, Godard, & Lefebvre, 2010).…”

Detection of Greenhouse Gases Using the Photoacoustic Spectroscopy

“…These microphones convert the sound signal into an electric signal, which is filtered and detected by a lock-in amplifier. Photoacoustic spectroscopy is widely used for the detection of several gases in the concentration range of ppbv and sub-ppbv Berrou et al, 2010;Sthel et al,2011;Harren et al,2008;Thomas, 2006;Elia et al, 2009;Sorvajärvi et al, 2009;Sigrist et al, 2008;Angelmahr et al,2006;Filho et al, 2006;Schramm et al, 2003;Harren et al, 2000;Miklos et al, 2001;Gondal, 1997;Repond & Sigrist, 1996;Sigrist, 1994aSigrist, , 1994b. There are some types of trace gas detection systems based on continuous wave (CW) CO 2 laser, optical parametric oscillator (OPO) in combination with photoacoustic spectroscopy and quantum cascade laser (QCL).…”