Intensités absolues des transitions de vibration-rotation des bandes ν2 et ν4 du méthane 12CH4

A general expansion, written in tensorial form in the T(d) group, of the transformed dipole moment of tetrahedral XY4 molecules (Loete, 1983) is employed to investigate the line strengths of the nu2 and nu4 bands of (C-12)H4. The method considers all the interactions to a given order and provides a more accurate interpretation of the strength perturbations and forbidden line intensities than is possible with polynomial methods. Experimental precision has been obtained for both strong and weak lines. The isolated band scheme is found to require two parameters for nu2 and five parameters for n4, while only three parameters are needed in the dyadic scheme.