Atmospheric Gas Absorption at DF Laser Wavelengths

Abstract

The absorption of twenty-four DF laser wavelengths ranging from 3.6128 microm P(1)(6) to 4.0464 microm P(3)(11) was measured for CH(4) , N(2)O, CO(2), and HDO vapor. Total absorption was calculated for the lines for each of these absorbing gases and for the N(2) and H(2)O continua independently and collectively for two representative transmission paths (midlatitude summer model); i.e., a vertical path from sea level to the edge of the atmosphere containing 2.93 cm precipitable water and a horizontal 8.0-km path at sea level at 14.2-Torr water vapor partial pressure (11.2 cm precipitable water). Transmission was >90% for twelve lines in the vertical path and >65% for thirteen lines in the horizontal path. A comparison of the measured absorption coefficients was made with calculated values of McClatchey and Selby for seventeen lines. Good agreement was obtained with most lines, the worst within a factor ~2 of predicted values.

High Resolution Spectral Survey of Molecular Absorption in the DF Laser Region - Measurements and Calculations

“…This higher methane absorption (. 00851 km" ) agrees well with the measurements of Spencer [4] (. 00752 km" ).…”

“…00752 km" ). Spencer's slightly smaller observed value is expected since his measurements were made on self-broadened CH 4 . Because the self-broadened width of CH.…”

“…Synthetic spectra have been generated in the region between 2545 cm and 2745 cm" for NJO, CH 4 and HDO. The parameters from the AFCRL Atmospheric Absorption Line Parameters Compilation [7] were used to generate the monochromatic transmission spectra for a temperature of 300 o K).…”

<title>DF laser application for hydrocarbon control in the atmosphere</title>

“…was at least halfthe maximum. Table 1 also demonstrates that the values of a obtained in our work are evidently in a good agreement with a large part of the experimental results performed by many other authors [3][4][5][6][7]. A specific feature of our measurements was an experimental confirmation of the relatively strong absorption in methane of the line P1 (5), which was predicted in previous calculations.…”

Thermal Imaging Systems' Relative Performance: 3-5 Micrometers vs 8-12 Micrometers.

“…Other measurements by Burch [29] are more widely used, having been employed by Spencer [32), Long [33] and Meredith [34] in their modeling. Burch's measurements are in general agreement with the Lowtran values (Lowtran is only about 20% less absorbing at 4 j im).…”