Knowledge Bank

We have developed a new program for the assignment of the FT methanol spectrum. The energies of the levels connected by the assigned transitions are evaluated by the Rydberg-Ritz combiuation principle. That is, we evaluate the energy level values $Ei$ which minimize the expression [ X^{2} = \sum\limits_{i,j} \frac{(E_{i} -E_{j} -\nu_{ij})^{2}}{\epsilon^{2}_{ij}} ] where $Ei$ and $Ej$ are the energies of the ith and jth level of the molecule, respectively, $\nu ij$ is the experimental wavenumber of the corresponding transition, and $ϵij$ its experimental accuracy. Very accurate values for the energies of the levels (accuracies of the order of $10-4cm-1)$ are thus obtained. Transitions connecting to a new level can be predicted by parabolic extrapolation, and the procedure is iterated. This program has been used for assigning more than 21000 absorption line of $CD3OH$ and for checking 36000 assignments of the parent species $CH3OH$. The energies of the CO-stretch levels obtained form the assignments of the IR transitions can be used for predicting new FIR laser lines. This, combined with the development of new pumping sources in the $IR1$, can highly facilitate the choice of new laser sources in the FIR region.