Long-path monitoring of NO2 with a 635 nm diode laser using frequency-modulation spectroscopy.

In situ monitoring of traffic-generated nitrogen dioxide (NO2) emissions using long-path absorption spectroscopy is reported. High-sensitivity detection of NO2 is achieved by employing two-tone frequency-modulation spectroscopy at a visible absorption band using a tunable high-power diode laser operated around 635 nm. A real-time absorption spectrometer is accomplished by repetitively applying a rectangular current pulse to the diode-laser operating current, allowing detection of isolated NO2 absorption lines.

Gas visualization of industrial hydrocarbon emissions.

Gases leaking from a polyethene plant and a cracker plant were visualized with the gas-correlation imaging technique. Ethene escaping from flares due to incomplete or erratic combustion was monitored. A leakage at a high-pressure reactor tank could be found and visualized by scanning the camera system over the industrial site.

Atomic mercury flux monitoring using an optical parametric oscillator based lidar system.

A newly developed optical parametric oscillator (OPO) based differential absorption lidar (DIAL) system has been applied to the monitoring of atomic mercury emissions at several chlor-alkali plants in Europe. The versatility of the system is illustrated by measured time series of mercury flux and movies of vertical and horizontal concentration distributions, which yield important input parameters for the environmental community. Long term measurements of the resonance absorption of mercury at 253.

Versatile mobile lidar system for environmental monitoring.

A mobile lidar (light detection and ranging) system for environmental monitoring is described. The optical and electronic systems are housed in a truck with a retractable rooftop transmission and receiving mirror, connected to a 40-cm-diameter vertically looking telescope. Two injection-seeded Nd:YAG lasers are employed in connection with an optical parametric oscillator-optical parametric amplification transmitter, allowing deep-UV to mid-IR wavelengths to be generated.

Atmospheric mercury near a chlor-alkali plant in Sweden.

Atmospheric mercury species/fractions were measured near a chlor-alkali plant in Sweden during August 28 to September 4, 2001. The concentration of total gaseous mercury in the plume from the plant was measured using TEKRAN and GARDIS instruments. Gaseous elemental mercury was measured using a light detection and ranging (LIDAR) technique.