Atmospheric CO2 absorption at the line center of P(20) CO2 laser radiation has been calculated at different altitudes by using the relationship 1 – exp(-ʃl2l1 kdl). In this calculation, the absorption caused by water vapor has not been included. The line strength and the half-width at 295 K and 1 atm pressure used are 5.09 × 10-4 cm-2 atm -1 and 0.07 cm -1 atm -1, respectively.
P. K. L. Yin and R. K. Long, "Atmospheric Absorption at the Line Center of P(20) CO2 Laser Radiation," Appl. Opt. 7, 1551-1553 (1968)