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SPECTRAL MEASUREMENTS OF GASEOUS SULFURIC ACID USING TUNABLE DIODE LASERS
Citation:
Eng, R., K. Nill, AND J. Butler. SPECTRAL MEASUREMENTS OF GASEOUS SULFURIC ACID USING TUNABLE DIODE LASERS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-78/019.
Description:
Using a tunable diode laser spectrometer with a spectral resolution of about 10 to the -4 power/cm, the important central portions of the two infrared absorption bands of H2SO4 at 8.2 micrometers (1222/cm) and 11.3 micrometers (880/cm) have been scanned at low pressure (approximately 1.2 Torr of H2SO4) and at atmospheric nitrogen pressure. Maximum absorption coefficients have been measured to be 6.5/cm/atm and 6.9/cm/atm at the 8.2 micrometer (1222/cm) and 11.3 micrometer (880/cm) bands, respectively. Interference spectra of SO2, CO2 and H2O near the H2SO4 absorption peaks at 1222/cm and 880/cm were scanned using a 1.1 m cell at 200C to determine interference-free regions. A spectroscopic method was used to measure the partial pressures of H2SO4, SO3 and H2O vapors above azeotropes of H2SO4 at 107C, 150C and 200C. The expected performance characteristics of an H2SO4 tunable diode laser stack monitor are considered on the basis of the above results.