Knowledge Bank

Seven absorption bands of $PH3$ at $3\mu m$, i.e $3\nu 2,2\nu 2+\nu 4$, $2\nu 4+\nu 2,\nu 1+\nu 2,\nu 3+\nu 2$, $\nu 3+\nu 4$ and $\nu 1+\nu 4$ were simultaneously analysed from spectra recorded at a resolution of $0.012cm-1$ using the Fourier transform spectrometer located at the Kitt Peak $Observatorya$. A theoretical model suited to the strong vibro-rotational couplings among the seven bands was used. Using ground state combination differences, several hundred transitions have been assigned for these seven bands in the range $2750-3600cm-1$. At present a set of 33 energy parameters was required to reproduce the experimental wavenumbers for six bands with an overall standard deviation of $0.1cm-1$ up to J = 9. 1355 lines were also measured and their analysis is underway. The final objective is to provide a complete prediction of line positions and intensities of Phosphine at $3\mu m$ for remote sensing of Saturn.