DIRECT CALCULATION OF DIATOMIC MOLECULAR SPECTRA (STUDIED BY FOURIER SPECTROMETRY)

Author Institution: Laboratoire de Spectrom\'{e}trie Ionique et Mol\'{e}culaire, Universit\'{e} de LyonThe large amount of data (wavenumbers and intensity) given by Fourier spectroscopy has shown the need of a program allowing the direct calculation of the whole of observed lines. We used methods indicated by C. Ath\’{e}nour in his Ph.D. thesis (Nice 1975). The principle of the program (ADIR) was carried out for the analysis of the iodine absorption spectrum (with S. Gerstenkorn, P. Luc, and A. Perrin). Other molecules with singlet, doublet and triplet transitions (NO, CN, YO, $P_{2}$) were further analyzed in collaboration with researchers of different laboratories. All the wavenumbers of measured lines (usually to a few thousands) are compared with wavenumbers determined from a given theoretical model. Parameters are chosen so that the corresponding RMS difference be minimum (in general for non weighted fits this value is about $0,001 cm^{-1}$). This direct treatment is particularly useful for the research of significant parameters, or of systematic errors, and for the calculation of lines of non-analyzed bands