Knowledge Bank

We report experimental line positions and intensities of the $3\nu 2$ and $\nu 2+\nu 4$ bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}NH3$ obtained from $0.011cm-1$ apodized resolution spectra recorded with the Fourier transform spectrometer at Kitt Peak National Observatory. 1366 lines with $J\prime \le 13$ have been assigned from which 1213 line positions with $(J\prime \le 12)$ are fitted using an effective rotation-inversion Hamiltonian to achieve a rms of $0.0069cm-1$. 726 intensity measurements are modelled to 12 terms of dipole moment expansion to $\pm 6$. The band strengths of $3\nu 2(s-a)$ at $2384.15cm-1$, of $3\nu 2(a-s)$ at $2895.52cm-1$, of $\nu 2+\nu 4(s-s)$ at $2540.53cm-1$, and of $\nu 2+\nu 4(a-a)$ at $2586.13cm-1$ are $0.61(3),0.244(7),0.186(3)$ and $0.174(25)cm-2atm-1$ respectively. A prediction of the line parameters has been generated for all lines with intensities greater than $0.1.10-6cm-2atm-1$ at 296K and submitted to HITRAN data base. Beside the lines belonging to the $3\nu 2/\nu 2+\nu 4$ system a number of strong features appear in the spectra which could be assigned by a preliminary study to the hot bands $(\nu 3-\nu 2),(\nu 1-\nu 2),(4\nu 2-\nu 2)$. Implications about the suitability of the Hamiltonian used is explored, given that the experimental accuracy is a factor of about 10 times better that has been achieved by the fit.