The absorption of twenty-four DF laser wavelengths ranging from 3.6128 μm P1(6) to 4.0464 μm P3(11) was measured for CH4, N2O, CO2, and HDO vapor. Total absorption was calculated for the lines for each of these absorbing gases and for the N2 and H2O 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.
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No absorption was measurable in pure water vapor. These values presume a 3.0 × 10−4 HDO molar fraction in natural water vapor and are provided for convenience in calculation.
Table VIII
Atmospheric Transmission of DF Laser Lines —Vertical Patha
Transmission from sea level to edge of atmosphere.
0.5 ppm by volume.
2.0 ppm by volume.
2.93 cm precipitable water at 1 atm total pressure.
314 ppm by volume at 1 atm total pressure.
Ref. 4.
Reg. 4.
See Fig. 2.
Table IX
Atmospheric Transmission of DF Laser Lines—Horizontal Patha
8.0 km path at sea level (294 K).
0.5 ppm by volume.
2.0 ppm by volume.
11.2-cm precipitable water at 1 atm total pressure (14.2 Torr partial pressure).
314 ppm by volume at 1 atm total pressure.
Ref. 4.
Ref. 4.
See Fig. 2.
Table X
Experimental Absorption Coefficients for Seventeen DF Laser Lines Compared with Theoretical Predictionsa
Horizontal path at sea level, 0.35 cm precipitable water/km, 272.2K.
Results of The Aerospace Corporation DF laser experiments for N2O, CH4, HDO, and CO2. Nitrogen continuum data from Ref. 4.
Ref. 11. .
Principal absorber.
Table XI
Uncertainty of Pλ Values in N2O and CH4 Measurements, at 294 K
Cell length (cm)
Pressure (Torr)
Uncertainty of Pλ × 103 Values (atm−1 cm−1)
±50%
±17%
±5%
200
760
0.25
0.75
200
100
1.9
5.7
10
760
5
15
10
100
38
113
1
760
50
150
1
100
380
1130
Table XII
Uncertainty of
Values in CO2 Measurements for 200-cm Cell at 760-Torr Total Pressure at 294 K
Line
Uncertainty of
Values (atm−1 cm−1)
±75%
±40%
±30%
P3(9)
0.10
—
—
P3(10)
—
0.20
—
P3(11)
—
—
0.30
Table XIII
Uncertainty of
Values for HDO and Water Vapor at 760 Torr Total Pressure at 294 K
Absorbing Specie
Uncertainty of
Values (atm−1 cm−1)
±100%
±70%
±50%
±25%
±9%
±4%
HDO
~13 × 10−3
~23 × 10−3
~41 × 10−3
~110 + 10−3
Water
~40 × 10−7
~68 × 10−7
~124 × 10−7
~332 × 10−7
Tables (13)
Table I
Composition of Dry Atmosphere to 90 Km
Constituent
Per cent by volume
Nitrogen
78.084
Oxygen
20.9476
Argon
0.934
Carbon dioxide
0.0314
Neon
1.818 × 10−3
Helium
5.24 × 10−4
Methane
2.0 × 10−4
Krypton
1.14 × 10−4
Nitrous oxide
5 × 10−5
Xenon
8.7 × 10−6
Hydrogen
5 × 10−5
Table II
Spectral Absorption Coefficient Comparison of DF P1(9) Line in CH4 (10-Cm and 200-Cm Test Cells)
Spectral absorption coefficient (atm−1 cm−1)
Cell size (cm)
Pressure (Torr)
10
25
50
Pλ × 103
10
725
452
290
Pλ × 103
200
768
451
257
Table III
Spectral Absorption Coefficient Comparison of DF P1(13) Line in N2O (1-Cm and 10-Cm Test Cells)
No absorption was measurable in pure water vapor. These values presume a 3.0 × 10−4 HDO molar fraction in natural water vapor and are provided for convenience in calculation.
Table VIII
Atmospheric Transmission of DF Laser Lines —Vertical Patha
Transmission from sea level to edge of atmosphere.
0.5 ppm by volume.
2.0 ppm by volume.
2.93 cm precipitable water at 1 atm total pressure.
314 ppm by volume at 1 atm total pressure.
Ref. 4.
Reg. 4.
See Fig. 2.
Table IX
Atmospheric Transmission of DF Laser Lines—Horizontal Patha
8.0 km path at sea level (294 K).
0.5 ppm by volume.
2.0 ppm by volume.
11.2-cm precipitable water at 1 atm total pressure (14.2 Torr partial pressure).
314 ppm by volume at 1 atm total pressure.
Ref. 4.
Ref. 4.
See Fig. 2.
Table X
Experimental Absorption Coefficients for Seventeen DF Laser Lines Compared with Theoretical Predictionsa
Horizontal path at sea level, 0.35 cm precipitable water/km, 272.2K.
Results of The Aerospace Corporation DF laser experiments for N2O, CH4, HDO, and CO2. Nitrogen continuum data from Ref. 4.
Ref. 11. .
Principal absorber.
Table XI
Uncertainty of Pλ Values in N2O and CH4 Measurements, at 294 K
Cell length (cm)
Pressure (Torr)
Uncertainty of Pλ × 103 Values (atm−1 cm−1)
±50%
±17%
±5%
200
760
0.25
0.75
200
100
1.9
5.7
10
760
5
15
10
100
38
113
1
760
50
150
1
100
380
1130
Table XII
Uncertainty of
Values in CO2 Measurements for 200-cm Cell at 760-Torr Total Pressure at 294 K
Line
Uncertainty of
Values (atm−1 cm−1)
±75%
±40%
±30%
P3(9)
0.10
—
—
P3(10)
—
0.20
—
P3(11)
—
—
0.30
Table XIII
Uncertainty of
Values for HDO and Water Vapor at 760 Torr Total Pressure at 294 K
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