Direct Measurement of SO₂ in Air by Laser Induced Fluorescence Spectrometry Using a Nontunable Laser Source

Abstract

Studies have been performed to evaluate a direct laser induced fluorescence (LIF) technique for measurements of atmospheric sulfur dioxide (SO₂). The technique is novel in that it uses a nontunable laser source that is spectrally coincident with absorption of the SO₂ molecule near 223 nm that allows sensitive measurements at environmentally relevant concentrations. In this report, the spectral characteristics and analytical capabilities of the nontunable LIF approach have been evaluated and preliminary measurements of ambient SO₂ are reported. The current limit of detection is 0.5 ppb and compares well to other analytical spectroscopy methods used for atmospheric measurements of SO₂. The results indicate strong feasibility for the nontunable LIF approach for SO₂ measurements and suggest ways for method improvement.

Keywords:

• Environmental monitoring
• Laser induced fluorescence (LIF)
• Sensors
• Sulfur dioxide (SO₂)

Acknowledgments

The authors gratefully acknowledge the Department of Chemistry and the School for Graduate Studies and Research at Youngstown State University for Research Support, and Advanced Monitoring, Inc. for the loan of the instrumentation used in these studies.