ULTRASENSITIVE, VISIBLE TUNABLE DIODE LASER DETECTION OF NO2

摘要

Recent advances in room-temperature visible diode lasers and ultrasensitive detection techniques have been exploited to create a highly sensitive tunable diode laser absorption technique for in situ monitoring of NO2 in the lower troposphere. High sensitivity to NO2 is achieved by probing the visible absorption band of NO2 with an AlGaInP diode laser at 640 or 670 nm combined with a balanced ratiometric electronic detection technique. We have demonstrated a sensitivity of 3.5 x 10(10) cm(-3) for neat NO2 in a l-m path at 640 nm and have estimated a sensitivity for ambient operation of 5 ppbv m (10 ppbv m at 670 nm), where ppbvm is parts in 10(9) by volume per meter of absorption path length, from measured pressure-broadening coefficients. (C) 1996 Optical Society of America [References: 17]