Knowledge Bank

Fourier transform spectra of $O3$ broadened by approximately 100 to 300 Torr $N2$ or dry air have been analyzed to determine both halfwidths and shifts for over 60 lines in the $9-\mu m$ region. The spectra were recorded at $0.005cm-1$ resolution with the McMath FTS at the National Solar Observatory on Kitt Peak, and halfwidths and line positions were determined using a nonlinear least-squares spectral fitting technique. Unshifted line positions were determined from additional FTS spectra of nearly pure $O3$ at low pressure, and all spectra were calibrated using well-known $H2O$ lines near $7.5\mu m$. Additional broadening measurements were made for 13 of the $O3$ lines using the tunable diode laser spectrometer at NASA Langley Research Center. The TDL results agree with the FTS measurements within 4%. Most of the lines measured belong to the R branch of the $\nu 1$ band of $O3$, covering the range of rotational quantum numbers $8\le J\prime \prime \le 45$ and $0\le Ka\prime \prime \le 11$. For both air and $N2$ broadening, the majority of observed halfwidths fall within the range 0.065 to $0.09cm-1$ atm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$, and the shifts vary between $+0.004cm-1atm-1$ and $-0.008cm-1$ atm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$. A strong dependence on rotational quantum numbers $J\prime \prime$ and $Ka\prime \prime$ is observed for both halfwidths and shifts.