High-sensitivity detection of trace gases using sweep integration and tunable diode lasers.

A tunable diode laser spectrometer capable of high-sensitivity detection of trace gases over a wide range of pressures is described. Infrared absorptions of 10(-3)% over path lengths of up to 200 m have been observed in low-pressure gases. In preliminary measurements at atmospheric pressure we have detected differential absorptions of 10(-3)% over path lengths of a few meters. Data are acquired by rapidly sweeping the laser wavelength over ~0.4 …