Absorption of Infrared Radiant Energy by CO_2 and H_2O, V Absorption by CO_2 between 1100 and 1835 cm^−1 (91–55 μm)*

Abstract

Samples of CO2 at pressures up to 21.3 atm and with paths as long as 1067 m have been employed to measure CO2 absorption between 1100 and 1835 cm−1. Most of the absorption is due to the ν1 and 2ν2 bands. These bands are forbidden for the symmetric 16O12C16O and 16O13C16O molecules and, therefore, produce only pressure-induced absorption. The asymmetric 16O12C18O and 16O12C17O molecules produce bands that contain components of both intrinsic and pressure-induced absorption. The integrated-absorption coefficient for the intrinsic absorption is 1.08×10−22 (±10%) molecules −1 cm2 cm−1. The integrated pressure-induced absorption coefficient is 1.68×10−22 (±8%) molecules −1 cm2 atm−1 cm−1.