A NEW ``RITZ'' PROGRAM FOR DIRECT ENERGY LEVEL FITTING AND FIR LASER LINE PREDICTION
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Date
1994
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Ohio State University
Abstract
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 $E_{i}$ which minimize the expression \[ X^{2} = \sum\limits_{i,j} \frac{(E_{i} -E_{j} -\nu_{ij})^{2}}{\epsilon^{2}_{ij}} \] where $E_{i}$ and $E_{j}$ are the energies of the ith and jth level of the molecule, respectively, $\nu_{ij}$ is the experimental wavenumber of the corresponding transition, and $\epsilon_{ij}$ its experimental accuracy. Very accurate values for the energies of the levels (accuracies of the order of $10^{-4} cm^{-1})$ 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 $CD_{3}OH$ and for checking 36000 assignments of the parent species $CH_{3}OH$. 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 $IR^{1}$, can highly facilitate the choice of new laser sources in the FIR region.
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1 K.M. Evenson, private communication.
Author Institution: Dipartimento di Fisica, dell'Universit\`{a} di Pisa; Molecular Physics Division, National Institute of Standards and Technology
Author Institution: Dipartimento di Fisica, dell'Universit\`{a} di Pisa; Molecular Physics Division, National Institute of Standards and Technology