Use of chemiluminescence techniques in portable lightweight highly sensitive instruments for measuring NO2 NOx and O3

摘要

Abstract: Small battery powered instruments for the sensitive detection of nitrogen dioxide (NO$-2$/), and ozone (O$-3$/) will be described. Because of their portability, they are ideal for studies of indoor air quality, measurements for aircraft, and other mobile platforms where power may be limited. For example, a miniature balloon borne sonde, based on the chemiluminescence between luminol and NO$-2$/ has recently demonstrated the ability to measure ambient mixing ratios of NO$-2$/ between ground level and an altitude of 33 km. The recent 'add-on's to the model LMA-3 NO$-2$/ analyzer are discussed. These include NO$-x$/ converters, techniques for eliminating the residual ozone and PAN interferences, as well as removing nonlinearity for mixing ratios of less than one ppbV. Finally, the model LOZ-4 ozone monitor will be described. Ozone is measured by using its chemiluminescence with the dye Eosin Y. In comparison with ethylene based ozone detectors, the LOZ-4 has better sensitivity, and does not require a troublesome and flammable gas. The O$-3$/ measurement is virtually interference free. In contrast, the widely used photometric O$-3$/ measurement technique has demonstrated significant interferences in polluted air (presumably due to organic compounds that absorb light at the 253.7 nm wavelength). Field measurements for all species are presented.!