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(Color) Spectral absorption features of Tabun (GA), Sarin (GB), Soman (GD), Cyclosarin (GF), VX, triethyl phosphate (TEP), dimethyl methylphosphonate (DMMP), and diisopropyl methylphosphonate (DIMP) in the region (top panel); positions and relative power levels of the laser output on the lasing transitions as a function of the wavelength (bottom panel). The left group of transitions corresponding to the P and R branches of the band are used in the present studies to evaluate the performance of the L-PAS spectrometer for the detection of CWAs.
Measured photoacoustic absorption spectra for ammonia, toluene, isopropanol, ethylene, ethanol, methanol, DIMP, and . Dots represent measured PAS signals at the peak of the laser lines.
L-PAS analyzer measurements of DIMP in 5 segments: (1) synthetic clean air, (2) Santa Monica city street air, (3) synthetic contaminated air with no DIMP, (4) synthetic contaminated air with DIMP present, and (5) synthetic contaminated air with no DIMP.
Measurements of DIMP in synthetic contaminated air and Santa Monica air over on different days to determine the sensitivity and PFP. Histograms for both days are shown as insets, with Gaussian curve fits used to estimate PFP. For example, for the situation represented in the top panel for highly contaminated synthetic ambient air, PFP for a detection (alarm) threshold of is calculated by taking the ratio of the area under the histogram for sensor reading and the total area under the histogram. For a alarm threshold, this situation yields an unacceptable level of PFP of about 10%. Increasing the threshold to lowers the PFP to an acceptable .
(Color) Measured receiver operation characteristic curve for the detection of DIMP, an accepted surrogate for Sarin, in the presence of Santa Monica street air and synthetic dirty air.
Components and concentrations used in the present study for synthetic clean air, outdoor Santa Monica air, and synthetic contaminated air.
Measurement results for each test segment.
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