STP957

    Tunable Diode Laser Absorption Spectrometry for Ultra-Trace Measurement and Calibration of Atmospheric Constituents

    Published: Jan 1987


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    Abstract

    There has been an ongoing quest for development of ever more sensitive and selective detection methods for studying various gas molecules of atmospheric importance. Both laboratory and ambient studies often require instrumentation capable of measuring ultratrace concentrations of such gases at, and below, the parts-per-billion range. Concurrently, accurate calibration standards, particularly those verified by independent techniques, are also required. The sensitive, selective, and versatile technique of infrared tunable diode laser absorption spectrometry is especially well suited for ultra-trace gas measurements and calibration standards verification. This combination, which is not shared by many other measurement techniques, results from the fact that diode laser spectrometers can be operated in an absolute mode as well as a more sensitive relative mode. In this paper, we discuss these capabilities and present specific examples for the measurement and calibration of ultra-trace levels of the important atmospheric gases nitrogen dioxide (NO2) and hydrochloric acid (HCl). In addition, we further discuss the application of tunable diode laser absorption spectrometry in the verification of NO2 permeation standards using the gas-phase titration reaction between nitric oxide (NO) and ozone (O3).

    Keywords:

    air quality, calibration, sampling, atmospheric measurements, laser absorption spectrometry, ultra-trace measurements


    Author Information:

    Fried, A
    Group leader and research scientist, Analytical Laser Spectrometry Group, Center for Analytical Chemistry, National Bureau of StandardsNational Center for Atmospheric Research, GaithersburgBoulder, MDCO

    Sams, R
    Group leader and research scientist, Analytical Laser Spectrometry Group, Center for Analytical Chemistry, National Bureau of StandardsNational Center for Atmospheric Research, GaithersburgBoulder, MDCO


    Paper ID: STP25707S

    Committee/Subcommittee: D22.01

    DOI: 10.1520/STP25707S


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