Real-time measurement of nitrogen dioxide in vehicle exhaust gas by mid-infrared cavity ring-down spectroscopy

摘要

-The application of pulsed cavity ring-down spectroscopy (CRDS) was demonstrated for the measurement of nitrogen dioxide (NO2) in automotive exhaust gas. The transition of the v_3 vibrational band assigned to the antisymmetric stretching mode of NO_2 was probed with a thermoelec-trically cooled, pulsed, mid-infrared, distributed feedback, quantum cascade laser (QCL) at 6.13 μm. The measurement of NO_2 in the exhaust gas from two diesel vehicles equipped with different afteitreatment devices was demonstrated using a CRDS-based NO_2 sensor, which employs a HEPA filter and a membrane gas dryer to remove interference from water as well as particulates in the exhaust gas. Stable and sensitive measurement of NO_2 in the exhaust gas was achieved for more than 30 minutes with a time resolution of 1 s.