NO(2) photometer Based on Solid-State Light Sources

A sensitive NO(2) analyzer, that uses a commercial LED emitting near 450 nm, has been developed. The prototype can measure NO(2) concentrations as low as 1 part in 10(9) as defined by the Environmental Protection Agency. The response time of the system is 1 min. In addition, a demonstration of the use of external-cavity frequency-doubled diode laser radiation to accomplish similar measurements is reported. However, because of low nonlinear optical conversion efficiencies, comparable detection limits were not possible. Nonetheless, frequency-doubled diode-laser wavelengths have the potential to reach farther into the UV than LED technology, allowing the detection and measurement of numerous other gaseous species of interest.