Knowledge Bank

Because the $7.9\mu m$ band of hydrogen peroxide $(\nu 6)$ is the strongest infrared band of this molecule, this spectral region is potentially useful for remote sensing of $H2O2$ in the atmosphere. Using new high resolution Fourier transform spectra $(Ft0.002cm-1)$ recorded in the $1190-1340cm-1$ spectral region, it has been possible to extend the $analysis(1)$ of the $\nu 6$ band of $H2O2$ leading to an improved analysis of the $(n,\top )=(0,1),(1,1),(2,1),(0,3),(1,3)$ torsional subbands. In addition to the $(\Delta r=\pm 1,\Delta Ka=\pm 2)$ torsion-rotation resonances within the $\nu 6=1$ vibrational state, which are usually observed for $H2O2$, the energy level calculation takes into account the $\nu 2=1\leftrightarrow \nu 6=1,\nu 3=1\leftrightarrow \nu 6=1$ and $\nu =0\leftrightarrow \nu 6=1$ vibration-rotation resonances. In this way an excellent agreement was obtained for the $\top =3$ torsion-rotation levels. On the other hand, for the $\top =1$ torsion-rotation levels the agreement was less satisfactory because in this case the scheme of vibration-torsion-rotation resonances is much more complicated. Finally line intensities were measured and satisfactorily reproduced, and a synthetic spectrum of the $\nu 6$ band of $H2O2$ was generated. Financial support from the European Community under contract EV5V-CT92-0076 is gratefully acknowledged.