Knowledge Bank

This preliminary work demonstrates the feasibility of simultaneous analysis of interacting vibro-rotational levels of methane belonging to the five vibrational states : $v4=2,v2=v4=1,v1=1,v3=1,v2=2$. The formalism used for this aim was developed in CHAMPION’s thesis. We take into account all the contributions due to operators up to the third order (diagonal and non-diagonal in vibrational quantum numbers). The experimental data are issued from various spectra i.e., Raman or infrared, cold or hot bands. The molecular constants corresponding to the vibronic ground state and to the two interacting $v4=1$ and $v2=1$ states are known from previous analysis. A program of prediction of transitions and adjustment of constants was written giving the possibility of plotting calculated spectra. The first results are a good starting point for an accurate analysis of the data for higher J values.