An ultra-highly sensitive and robust CH4 sensor is reported based on a 3.3 μm interband cascade laser (ICL) and a low-noise differential photoacoustic (PAS) cell. The ICL emission wavelength targeted a fundamental absorption line of CH4 at 2988.795 cm-1 with an intensity of 1.08 × 10-19 cm/molecule. The double-pass and differential design of the PAS cell effectively enhanced the PAS signal amplitude and decreased its background noise. The wavelength modulation depth, operating pressure and V-T relaxation promotion were optimized to maximize the sensor detection limit. With an integration time of 90 s, a detection limit of 0.6 ppb was achieved. No additional water or air laser cooling were required and thereby allowing the realization of a compact and robust CH4 sensor.
Sub-ppb-level CH4 detection by exploiting a low-noise differential photoacoustic resonator with a room-temperature interband cascade laser
Patimisco P.;Sampaolo A.;Giglio M.;Spagnolo V.;
2020-01-01
Abstract
An ultra-highly sensitive and robust CH4 sensor is reported based on a 3.3 μm interband cascade laser (ICL) and a low-noise differential photoacoustic (PAS) cell. The ICL emission wavelength targeted a fundamental absorption line of CH4 at 2988.795 cm-1 with an intensity of 1.08 × 10-19 cm/molecule. The double-pass and differential design of the PAS cell effectively enhanced the PAS signal amplitude and decreased its background noise. The wavelength modulation depth, operating pressure and V-T relaxation promotion were optimized to maximize the sensor detection limit. With an integration time of 90 s, a detection limit of 0.6 ppb was achieved. No additional water or air laser cooling were required and thereby allowing the realization of a compact and robust CH4 sensor.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
