Knowledge Bank

The determination of atmospheric $HNO3$ from both the solar spectrum and the atmosphere emission spectrum is based on quantitative measurements in the laboratory. In this research we extend previous studies that were limited to room temperatures, to lower temperature. These lower temperatures reflect more closely actual atmospheric conditions. The absorption spectrum of $HNO3$ has been examined around 7.5 $\mu m$ using a Fourier Transform Interferometer. Sample pressures ranged from 0.05 to 1.1 Torr and temperatures from -33 to +21$\mathrm{<mrow\; data-mjx-texclass="ORD">\circ </mrow>}$ C. A preliminary value of about $1100cm-2$ $amagat-1$ at 293 K is determined for the integrated band intensity between 1250 and 1375 wavenumbers.