Knowledge Bank

The $N2O$ laser operates in the atmospheric window occurring in the wave-length region around 10 microns. Since the amount of $N2O$ in the atmosphere is very small, very little absorption of this radiant energy is expected over long atmospheric paths. A detailed study of the rotational lines of the $00\circ 1-10\circ 0$ band of $N2O$ was undertaken in order to study the effect of atmospheric absorption. The laser tube containing $N2O$ was placed in a cavity in which one mirror was replaced by a grating.$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ By turning the grating 65 rotational lines appeared whose frequencies were determined. Absorption of this energy by $N2O$ was observed by use of a 10 m long absorption cell filled with $N2O$. When the absorption cell was filled with $CO2$ strong absorption was observed at R(10), R(12), R(14) and P(7) of the studied band of $N2O$. This absorption occurs since these lines coincide in frequency with lines of the $00\circ 1-10\circ 0$ band of $CO2$. It follows that the strongest lines of $N2O$ occurring around P(19), are not obstructed by $CO2$ in the atmosphere. This research was sponsored by the Air Force Office of Scientific Research under Grant EOOAR 69 0053, through the European Office of Aerospace Research (OAR), U.S. Air Force.