Sensitive detection of formaldehyde using an interband cascade laser near 3.6 μm

[摘要] We report the development of a formaldehyde (H2CO) trace gas sensor using a continuous wave (CW), thermoelectrically-cooled (TEC), distributed-feedback interband cascade laser (DFB-ICL) at 3.6 mu m. Wavelength modulation spectroscopy was used to detect the second harmonic spectra of a strong H2CO absorption feature centered at 2778.5 cm(-1) (3599 nm) in its nu(1) fundamental vibrational band. A compact and novel multipass cell (7.6-cm physical length and 32-ml sampling volume) was implemented to achieve an effective optical path length of 3.75 m. A minimum detection limit of 6 parts per billion (ppb) at an optimum gas pressure of 200 torr was achieved with a 1-s data acquisition time. An Allan-Werle deviation analysis was performed to investigate the long-term stability of the sensor system and a 1.5 ppb minimum detectable concentration could be achieved by averaging up to 140 s. Absorption interference effects from atmospheric H2O (2%) and CH4 (5 ppm) were also analyzed in this work and proved to be insignificant for the current sensor configuration. (C) 2015 Elsevier B.V. All rights reserved.

[发布日期] 2015-12-31

[关键词] Formaldehyde;Absorption spectroscopy;Interband cascade laser;Trace gas detection