Sensitive detection of formaldehyde using an interband cascade laser near 3.6 μm.
- Resource Type
- Article
- Authors
- Ren, Wei; Luo, Longqiang; Tittel, Frank K.
- Source
- Sensors & Actuators B: Chemical. Dec2015, Vol. 221, p1062-1068. 7p.
- Subject
- *FORMALDEHYDE
*GAS detectors
*THERMOELECTRIC effects
*ABSORPTION
*TRACE gases
- Language
- ISSN
- 0925-4005
We report the development of a formaldehyde (H 2 CO) trace gas sensor using a continuous wave (CW), thermoelectrically-cooled (TEC), distributed-feedback interband cascade laser (DFB-ICL) at 3.6 μm. Wavelength modulation spectroscopy was used to detect the second harmonic spectra of a strong H 2 CO absorption feature centered at 2778.5 cm −1 (3599 nm) in its v 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 H 2 O (2%) and CH 4 (5 ppm) were also analyzed in this work and proved to be insignificant for the current sensor configuration. [ABSTRACT FROM AUTHOR]